BACKGROUND

[0001] Detection and processing of Radio Frequency (RF) signals at a front end of a receiver, which is part of a signal chain, is a critical step in RF signal processing.

Applications such as Global Positioning System (GPS), Magnetic Resonance Imaging (MRI), and highly attenuated signal receivers can benefit from highly parallel signal acquisitions. However, current RF detection and processing schemes use non-linear multipliers using RF electronics for down conversion of the RF signal to an intermediate frequency (IF) signal. The down conversion is generally performed by a mixer circuit that receives a local oscillating signal. This local oscillating signal is generated by a local oscillator (i.e.., a clock source) such as a phase locked loop (PLL).

[0002] This clock source for up or down frequency conversion may be generated off- chip or by an off-the instrument. For example, MRI apparatus has an off-chip clock source used for up or down conversion of RF input signals. Continuing with the MRI apparatus example, one reason for having a dedicated off-chip clock source is that available clock signals used by the MRI apparatus have frequencies not suitable for down conversion. Also, the number of available channels are limited in existing RF receivers (e.g., 10 to 20 channels), which increases the complexity of implementing highly parallel sensing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The embodiments of the disclosure will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the disclosure, which, however, should not be taken to limit the disclosure to the specific embodiments, but are for explanation and understanding only.

[0004] Fig. 1 illustrates a three terminal (3T) high input impedance Spin Torque

Oscillator (STO) with built-in Mixer, according to some embodiments of the disclosure.

[0005] Fig. 2A illustrates a plot showing a single-sided amplitude spectrum of an input Radio Frequency (RF) signal which is input to the 3T STO with built-in Mixer, according to some embodiments of the disclosure.

[0006] Fig. 2B illustrates a plot showing magnetization oscillation produced by the

3T STO with built-in Mixer, according to some embodiments of the disclosure.

[0007] Fig. 2C illustrates a plot showing a single-sided amplitude spectrum of the output of the 3T STO with built-in Mixer, according to some embodiments of the disclosure. [0008] Fig. 3 illustrates a 3T low input impedance STO with built-in Mixer, according to some embodiments of the disclosure.

[0009] Fig. 4 illustrates a 3T high input impedance STO with built-in Mixer, according to some embodiments of the disclosure.

[0010] Fig. 5 illustrates a 3T low input impedance STO with built-in Mixer, according to some embodiments of the disclosure.

[0011] Fig. 6 illustrates an RF detection apparatus for Magnetic Resonance Imaging

(MRI) having the 3T STO with built-in Mixer, according to some embodiments of the disclosure, according to some embodiments of the disclosure.

[0012] Fig. 7 illustrates an RF receiver coil with controlled detuning of the RF detection apparatus of Fig. 6, in accordance with some embodiments of the disclosure.

[0013] Fig. 8 illustrates a balun (i.e., common-mode choke) of the RF detection apparatus of Fig. 6, in accordance with some embodiments of the disclosure.

[0014] Fig. 9 illustrates an RF detection apparatus for a wireless receiver having the

3T STO with built-in Mixer, according to some embodiments of the disclosure.

[0015] Fig. 10 illustrates an apparatus, with the 3T STO having built-in Mixer, showing parallel sensing using multiple receiver coils at a single frequency, according to some embodiments of the disclosure.

[0016] Fig. 11 illustrates an apparatus, with the 3T STO having built-in Mixer, showing parallel sensing with frequency multiplexing, according to some embodiments of the disclosure.

[0017] Fig. 12 illustrates a sensing array formed with the apparatus of Fig. 10, according to some embodiments of the disclosure.

[0018] Fig. 13 illustrates a sensing array formed with the apparatus of Fig. 11, according to some embodiments of the disclosure.

[0019] Fig. 14A illustrates an equivalent vector spin circuit for STO RF detector with locally generated oscillator, according to some embodiments of the disclosure.

[0020] Fig. 14B illustrates a plot showing tunability of the STO, according to some embodiments of the disclosure.

[0021] Fig. 15 illustrates a smart device or a computer system or a SoC (System-on-

Chip) with the 3T STO with built-in Mixer, according to some embodiments. DETAILED DESCRIPTION

[0022] Some embodiments describe a spin torque oscillator (STO) based radio frequency (RF) detection scheme. In some embodiments, the RF detector includes an STO which is a three terminal (3T) device with an integrated mixer (i.e., built-in mixer) and formed using a magnetic junction and a spin orbit coupling layer (e.g., a layer that exhibits spin Hall effect). In some embodiments, the RF detector is a multiplier that naturally provides a local clock demodulation frequency via inherent precessional dynamics of nanomagnets. In some embodiments, the 3T STO configuration is used to down convert the input RF signal to a corresponding base band as set by the local STO.

[0023] There are many technical effects/benefits of the various embodiments. For example, no special clock source is needed to down convert an RF signal to an IF signal. The size of the 3T STO with built-in Mixer of the various embodiments is much smaller than traditional mixers with local oscillators (LOs). As such, parallel sensing arrays with small form factor can be formed using the STOs of the various embodiments. The parallel sensing arrays using the STOs of the various embodiments allow for large number of parallel oscillators for increased signal collection (e.g., greater than 1000 channels). Other technical effects will be evident from the various embodiments and figures.

[0024] In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present disclosure. It will be apparent, however, to one skilled in the art, that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring embodiments of the present disclosure.

[0025] Note that in the corresponding drawings of the embodiments, signals are represented with lines. Some lines may be thicker, to indicate more constituent signal paths, and/or have arrows at one or more ends, to indicate primary information flow direction. Such indications are not intended to be limiting. Rather, the lines are used in connection with one or more exemplary embodiments to facilitate easier understanding of a circuit or a logical unit. Any represented signal, as dictated by design needs or preferences, may actually comprise one or more signals that may travel in either direction and may be implemented with any suitable type of signal scheme.

[0026] Throughout the specification, and in the claims, the term "connected" means a direct connection, such as electrical, mechanical, or magnetic connection between the things that are connected, without any intermediary devices. The term "coupled" means a direct or indirect connection, such as a direct electrical, mechanical, or magnetic connection between the things that are connected or an indirect connection, through one or more passive or active intermediary devices. The term "circuit" or "module" may refer to one or more passive and/or active components that are arranged to cooperate with one another to provide a desired function. The term "signal" may refer to at least one current signal, voltage signal, magnetic signal, or data/clock signal. The meaning of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on."

[0027] The terms "substantially," "close," "approximately," "near," and "about," generally refer to being within +/- 10% of a target value (unless specifically specified). Unless otherwise specified the use of the ordinal adjectives "first," "second," and "third," etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking or in any other manner.

[0028] For the purposes of the present disclosure, phrases "A and/or B" and "A or B" mean (A), (B), or (A and B). For the purposes of the present disclosure, the phrase "A, B, and/or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0029] The terms "left," "right," "front," "back," "top," "bottom," "over," "under," and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions.

[0030] For purposes of the embodiments, the transistors in various circuits and logic blocks described here are metal oxide semiconductor (MOS) transistors or their derivatives, where the MOS transistors include drain, source, gate, and bulk terminals. The transistors and/or the MOS transistor derivatives also include Tri-Gate and FinFET transistors, Gate All Around Cylindrical Transistors, Tunneling FET (TFET), Square Wire, or Rectangular Ribbon Transistors, ferroelectric FET (FeFETs), or other devices implementing transistor functionality like carbon nanotubes or spintronic devices. MOSFET symmetrical source and drain terminals i.e., are identical terminals and are interchangeably used here. A TFET device, on the other hand, has asymmetric Source and Drain terminals. Those skilled in the art will appreciate that other transistors, for example, Bi-polar junction transistors (BJT PNP/NPN), BiCMOS, CMOS, etc., may be used without departing from the scope of the disclosure. [0031] Fig. 1 illustrates an apparatus 100 including a 3T high input impedance STO with built-in Mixer 100, according to some embodiments of the disclosure. Here, the STO with built-in Mixer is simply referred to as an STO. In some embodiments, apparatus 100 comprises STO 101, Bias T (or Bias Tee) network 102, Isolator 103, and first, second, and third non-magnetic conductors 104a, 104b, and 104c, respectively.

[0032] In some embodiments, STO 101 includes a magnetic junction having free and fixed magnetic layers such that one of the magnetic layers is an in-plane magnet and another is a perpendicular magnet. In some embodiments, the free and fixed magnetic layers are separated by a metal. In one such embodiment, the magnetic junction is a spin valve. In some embodiments, the free and fixed magnetic layers are separated by a dielectric (e.g., MgO). In one such embodiment, the magnetic junction is a magnetic tunneling junction (MTJ).

[0033] In some embodiments, STO 101 includes a spin orbit coupling (SOC) layer coupled to the free magnet of the magnetic junction. In some embodiments, the SOC layer is biased by a SOC DC bias. In some embodiments, this DC bias defines in-part the center frequency of oscillation of STO 101. In some embodiments, the SOC layer is coupled to first and second non-magnetic conductors 104a/b on either ends of the SOC layer, respectively. In some embodiments, the fixed magnet of STO 101 is coupled directly or indirectly to a metal electrode which in turn is coupled to third non-magnetic conductor 104c. In some embodiments, input RF signal (RFIN) is provided to first non-magnetic conductor 104a. In one such embodiment, the input impedance ZIN of apparatus 100 is high because the impedance looking into apparatus 100 sees non-magnetic conductors 104a/b.

[0034] In some embodiments, Bias T 102 biases STO 101 with a DC bias. In some embodiments, this DC bias defines in-part the center frequency of oscillation of STO 101. In some embodiments, Bias T 102 is a three port network (often arranged in a T shape) which is used for setting the DC bias point of STO 101 without disturbing other components. In some embodiments, Bias T 102 is a diplexer. Conceptually, Bias T 102 can be viewed as an ideal capacitor that allows AC (alternating current) through but blocks the DC bias and an ideal inductor that blocks AC but allows DC (direct current).

[0035] In some embodiments, the low frequency port of Bias T 102 is used to set the bias. Here, the low frequency port receives the DC bias and control. In some embodiments, a first high frequency port of Bias T 102 passes the RF signals but blocks the biasing levels. For example, low frequency IF signal, which is down modulated from the RF input at the Zin port by the STO, is received at the output of Isolator 103 (i.e., IFOUT). In some embodiments the first high frequency port of Bias T 102 is coupled to Isolator 103. In some embodiments, a second high frequency port of Bias T 102 passes both the RF signal and the DC bias. Here, the second high frequency port of Bias T 102 is coupled to third non-magnetic conductor 104a.

[0036] In some embodiments, Isolator 103 isolates Bias T 102 from other components. In some embodiments, Isolator 103 is a non-reciprocal device, with a non- symmetric scattering matrix. In some embodiments, Isolator 103 suppresses backward reflection of RF signal from the detection circuitry (i.e., from STO 101).

[0037] In some embodiment, the intermediate frequency output (IFOUT) is provided across Isolator 103 and second non-magnetic conductor 104b. This IFOUT is the down converted RFIN signal. In some embodiments, the output impedance Ζουτ across Isolator 103 and second non-magnetic conductor 104b is high impedance. In some embodiments, another Isolator (not shown) is provided at the input and coupled to non-magnetic conductor 104a. As such, RFIN is provided uni-directionally to non-magnetic conductor 104a. In some embodiments, Isolator 103 is optional and can be removed.

[0038] In some embodiments, STO 101 receives RFIN and down converts it to IFOUT using the oscillation behavior of STO 101 and its built-in mixer function. In some embodiments, the oscillation behavior of STO 101 is achieved from the metastability of the perpendicular magnet and the in-plane magnet. In some embodiments, when input RF current of the RF signal is provided to the SOC layer of STO 101, STO 101 begins to oscillate and mixes the RF signal to a lower frequency (i.e., down converts it).

[0039] While various embodiments describe the apparatus for amplitude modulation, the same concept can be extrapolated for FM (frequency modulation) and PM (phase modulation). For FM, a filter is used with a roll-off. In some embodiments, this filter is placed after Isolator 103 as illustrated by filters 1002 in Fig. 10.

[0040] Fig. 2A illustrates plot 200 showing a single-sided amplitude spectrum of an input RF (RFIN) which is an amplitude modulated (AM) signal at 9 GHz. Here, RFIN is input to apparatus 100 and received by STO 101. It is pointed out that those elements of Fig. 2 A having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such. Here, x-axis is frequency (GHz) and y-axis is magnitude of the power spectral density of the measured current from MTJ. [0041] Fig. 2B illustrates plot 220 showing closed loop magnetization oscillation produced by STO 101 of apparatus 100, according to some embodiments of the disclosure. In some embodiments, the oscillation is produced by the metastability caused by the magnetization direction 221 of the magnet of STO 101 with perpendicular anisotropy relative to the magnetization direction 222 of the magnet of STO 101 with in-plane anisotropy. Here, plot 220 shows the magnetic dynamics of STO 101 with continuous oscillations centered at 7.5GHz.

[0042] Fig. 2C illustrates plot 230 showing a single-sided amplitude spectrum of

RFOUT (or IFOUT) of apparatus 100, according to some embodiments of the disclosure. Here, IF OUT is the down converted or detected signal. Plot 230 shows that IFOUT has a frequency of 1.5GHz which is produced by down converting of RFIN from 9GHz via STO 101, in accordance with some embodiments. In some embodiments, the frequency of the down converted signal can be adjusted by adjusting the DC bias and control to Bias T 102 (which in turn biases STO 101) and/or the DC bias of SOC bias. In some embodiments, the down converted signal is detected and processed by a digital signal processing logic (not shown).

[0043] Fig. 3 illustrates apparatus 300 with a 3T low input impedance STO with built-in Mixer, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 3 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such. So as not to obscure the embodiments of Fig. 3, differences between Fig. 1 and Fig. 3 are described.

[0044] Compared to apparatus 100, here STO 101 is oriented such that ZIN is low compared to ZIN of apparatus 100. In some embodiments, when RFIN is received by apparatus 300 such that RFIN sees the SOC layer of STO 101 instead of first and third nonmagnetic conductors 104a/c (as in apparatus 100), RFIN sees lower impedance because the SOC layer has lower impedance than first and third non-magnetic conductors 104a/c. As such, apparatus 300 can be used for RF applications that desire lower input impedance while apparatus 100 can be used for RF applications that desire higher input impedance.

[0045] Fig. 4 illustrates apparatus 400 with a detailed view of STO 101/401, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 4 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such. [0046] In some embodiments, STO 101/401 comprises magnetic junction 402 and

SOC layer 403. In some embodiments, magnetic junction 402 is an MTJ having a dielectric (e.g., MgO) coupled between its magnets. In one example, MTJ 402 comprises stacking a ferromagnetic layer (e.g., Free Magnet) with a tunneling dielectric (e.g., MgO) and another ferromagnetic layer (Fixed Magnet). In one case, the magnetization direction of the fixed magnetic layer is perpendicular relative to the magnetization direction of the free magnetic layer (i.e., magnetization directions of the free and fixed magnetic layers are not parallel, rather they are orthogonal).

[0047] For example, the magnetization direction of the free magnetic layer is in-plane while the magnetization direction of the fixed magnetic layer is perpendicular to the in-plane. In another case, the magnetization direction of the fixed magnetic layer is in-plane while the magnetization direction of the free magnetic layer is perpendicular to the in-plane. The thickness of a ferromagnetic layer (i.e., fixed or free magnetic layer) may determine its magnetization direction.

[0048] For example, when the thickness of the ferromagnetic layer is above a certain threshold (depending on the material of the magnet, e.g. approximately 1.5nm for CoFe), then the ferromagnetic layer exhibits magnetization direction which is in-plane. Likewise, when the thickness of the ferromagnetic layer is below a certain threshold (depending on the material of the magnet), then the ferromagnetic layer exhibits magnetization direction which is perpendicular to the plane of the magnetic layer. Other factors may also determine the direction of magnetization.

[0049] For example, factors such as surface anisotropy (depending on the adjacent layers or a multi-layer composition of the ferromagnetic layer) and/or crystalline anisotropy (depending on stress and the crystal lattice structure modification such as FCC, BCC, or L10- type of crystals, where L10 is a type of crystal class which exhibits perpendicular magnetizations), can also determine the direction of magnetization.

[0050] In some embodiments, the free magnetic layer is coupled to SOC layer 403.

In some embodiments, the free magnet is made from CFGG (i.e., Cobalt (Co), Iron (Fe), Germanium (Ge), or Gallium (Ga) or a combination of them). In some embodiments, the free magnet is formed from Heusler alloys. Heusler alloys are ferromagnetic metal alloys based on a Heusler phase. Heusler phases are intermetallic with certain composition and face- centered cubic crystal structure. The ferromagnetic property of the Heusler alloys are a result of a double-exchange mechanism between neighboring magnetic ions. In some embodiments, the free magnet is a Heusler alloy lattice matched to Ag (i.e., the Heusler alloy is engineered to have a lattice constant close (e.g., within 3%) to that of Ag). In some embodiments, the free magnetic layer is formed of Heusler alloy, Co, Fe, Ni, Gd, B, Ge, Ga, or a combination of them.

[0051] In some embodiments, Heusler alloys that form input and/or output magnets

202 and 203, respectively, are one of: Cu ₂ MnAl, Cu ₂ MnIn, Cu ₂ MnSn, Ni ₂ MnAl, Ni ₂ MnIn, Ni ₂ MnSn, Ni ₂ MnSb, Ni ₂ MnGa Co ₂ MnAl, Co ₂ MnSi, Co ₂ MnGa, Co ₂ MnGe, Pd ₂ MnAl, Pd ₂ MnIn, Pd ₂ MnSn, Pd ₂ MnSb, Co ₂ FeSi, Co ₂ FeAl, Fe ₂ VAl, Mn ₂ VGa, Co ₂ FeGe, MnGa, or MnGaRu.

[0052] In some embodiments, the magnet with perpendicular magnetic anisotropy

(PMA) is formed form multiple layers in a stack (i.e., perpendicular magnetic layer is formed of multiple layers). The multiple thin layers can be layers of Cobalt and Platinum (i.e., Co/Pt), for example. Other examples of the multiple thin layers include: Co and Pd; Co and Ni; MgO, CoFeB, Ta, CoFeB, and MgO; MgO, CoFeB, W, CoFeB, and MgO; MgO, CoFeB, V, CoFeB, and MgO; MgO, CoFeB, Mo, CoFeB, MgO; Mn _x Ga _y ; Materials with L10 crystal symmetry; or materials with tetragonal crystal structure. In some embodiments, the perpendicular magnetic layer is formed of a single layer of one or more materials. In some embodiments, the single layer is formed of MnGa. In some embodiments, the perpendicular magnetic layer is formed of one of: a Heusler alloy, Co, Fe, Ni, Gd, B, Ge, Ga, or a combination of them.

[0053] A wide combination of materials can be used for material stacking of MTJ

402. For example, the stack of materials include: Co _x Fe _y B _z , MgO, Co _x Fe _y B _z , Ru, Co _x Fe _y B _z , IrMn, Ru, Ta, and Ru, where 'x,' 'y,' and 'z' are fractions of elements in the alloys. Other materials may also be used to form MTJ 402. In some embodiments, MTJ 402 stack comprises free magnetic layer, MgO tunneling oxide, a fixed magnetic layer which is a combination of CoFe/Ru/CoFe layers referred to as Synthetic Anti-Ferromagnet (SAF) - based, and an Anti-Ferromagnet (AFM) layer. The SAF layer has the property, that the magnetizations in the two CoFe layers are opposite, and allows for cancelling the dipole fields around the free magnetic layer such that a stray dipole field will not control the free magnetic layer.

[0054] In some embodiments, SOC layer 403 is coupled to first non-magnetic layer

104a (e.g., Cu) at one end and is coupled to second non-magnetic layer 104b (e.g., Cu) at the other end. In some embodiments, SOC layer 403 is formed with spin Hall effect (SHE) material, where the SHE material converts charge current Iw (or write current or RF input current) to spin current Is.

[0055] In some embodiments, the stack of STO 401 comprises MTJ 402, SHE

Interconnect or electrode 403, and non-magnetic metal(s) 104a/b/c. In one example, MTJ

402 comprises stacked ferromagnetic layer with a tunneling dielectric and another ferromagnetic layer. One or both ends along the horizontal direction of SHE Interconnect

403 is formed of non-magnetic metals 104a/b, in accordance with some embodiments.

[0056] In some embodiments, SHE Interconnect 403 (or the write electrode) is made of one or more of β-Tantalum (β-Ta), Ta, β-Tungsten (β-W), W, Pt, Copper (Cu) doped with elements such as Iridium, Bismuth and any of the elements of 3d, 4d, 5d and 4f, 5f periodic groups in the Periodic Table which may exhibit high spin orbit coupling. SHE Interconnect 403 transitions into high conductivity non-magnetic metal(s) 104a/b to reduce the resistance of SHE Interconnect 403. The non-magnetic metal(s) 104a/b/c are formed from one or more of: Cu, Co, a-Ta, Al, CuSi, or iSi.

[0057] In this example, the applied current I _w (i.e., input RF current IRF = A(t)sin(cot)

+ IdcSHE) is converted into spin current by SHE Interconnect 403, where A(t) is the amplitude as a function of time, 'ω' is the frequency of the RF input signal, and IdcSHE is the DC bias to the SHE layer 403. This spin current switches the direction of magnetization of the free layer. The direction of the magnetization in the free magnet layer is decided by the direction of the applied RF charge current.

[0058] For example, positive RF charge currents (i.e., currents flowing in the +y direction) produce a spin injection current with transport direction (along the +z direction) and spins pointing to the +x direction. The injected spin current in-turn produces spin torque to align the free magnet (coupled to the SHE material) in the +x or -x direction. The injected spin current I _s generated by a charge current l _c (same as IRF) in SHE interconnect 403 is given by:

T _s = P _SHE (w, t, X _sf , 9 _SHE ) (z x T _c ) . . . (1) where, the vector of spin current l _s = 7 _† — / _j, is the difference of currents with spin along and opposite to the spin direction, z is the unit vector perpendicular to the interface, P _SHE is the spin Hall injection efficiency which is the ratio of magnitude of transverse spin current to lateral charge current, w is the width of the magnet, t is the thickness of the SHE

Interconnect 403, X _S f is the spin flip length in SHE Interconnect 403, 9 _SHE is the spin Hall angle for SHE Interconnect 403 to free ferromagnetic layer interface. The injected spin angular momentum responsible for the spin torque given by:

[0059] In some embodiments, when the free magnetic layer is of PMA (i.e., is a perpendicular magnet), then the direction of IRF causes the magnetization of the free magnet to point towards either +z or -z direction. Because one magnet of STO 401 has PMA while the other magnet has in-plane magnetization, STO 401 has inherent metastability which causes it to oscillate. As such, STO 401 produces magnetic oscillation MSTO = sin(cot) without an externally provided clock signal or local oscillating signal. Another technical effect of STO 401 is that, the output of STO 401 (i.e.., RF signal output from electrode 104c is down converted in frequency). As such, STO 401 provides both oscillation and mixing functions together. A circuit simulation model of STO 401 is described with reference to Figs. 14A-B.

[0060] Fig. 5 illustrates apparatus 500 3T having low input impedance STO with built-in Mixer, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 5 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such. Fig. 5 is described with reference to Fig. 3 and Fig. 4. In this case, STO 401 is reoriented (as shown in Fig. 3) such that the input RF signal RFIN sees a low input impedance because it sees SHE interconnect 403 instead of non-magnetic conductors 104a/b. Structure wise, STO 501 is the same as STO 401 but reoriented to provide low input impedance.

[0061] Fig. 6 illustrates an RF detection apparatus 600 for Magnetic Resonance

Imaging (MRI) having the 3T STO with built-in Mixer, according to some embodiments of the disclosure, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 6 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such. In some embodiments, apparatus 600 comprises an RF Receiver (Rx) 601, Balun 602, Low Noise Amplifier 603, STO apparatus 604 (e.g., apparatus 100/300/400/500), and Digital Signal Processing logic 605.

[0062] In some embodiments, RF Rx 601 is an Rx coil or antenna array with a preferred quality factor Q (e.g., in the range of 1 to 100) tuned to the incoming

RF/electromagnetic radiation. One such embodiment of RF Rx 601 is illustrated with reference to Fig. 7. Fig. 7 illustrates an RF receiver coil 700 with controlled detuning of the RF detection apparatus of Fig. 6, in accordance with some embodiments of the disclosure.

[0063] In some embodiments, RF receiver coil 700 comprises a loop having inductor

L and capacitor C pairs 701. The loop defines an RF signal collection area 702, in accordance with some embodiments. In this example, four pairs of L and C are shown. In each pair of L and C, L and C are coupled together in parallel. In some embodiments, a detuning circuit is integrated in the loop. In some embodiments, the detuning circuit comprises of active and/or passive devices. In some embodiments, the detuning circuit includes diode 703 with an anode terminal coupled to one L and C pair and a cathode coupled to another L and C pair.

[0064] In some embodiments, diode 703 is controlled via a controls signal. In some embodiments, the control signal provides RF protection to the sensitive receive electronics. In some embodiments, the control signal detunes the coil by adding resistance. For example, control signal adds resistive loss to detune the high Q of the oscillator. In the case of MRI, the chamber of MRI coils is pulsed with electromagnetic pulses (e.g., killo Watt pulses). In some embodiments, the anode and cathode of diode 703 are also coupled to inductors which receive the input RF signal. In some embodiments, the detuning circuit controls the center frequency and/or the quality factor of the RF circuit. In some embodiments, the detuning circuit can be a MEMS (micro-electrical-mechanical-system) switch to enable high contrast switching with EMI (electromagnetic interference) resistance.

[0065] Referring back to Fig. 6, in some embodiments, Balun 602 couples to RF Rx

601 and to LNA 603. One embodiment of Balun 602 is illustrated with reference to Fig. 8. Fig. 8 illustrates Balun 800 (i.e., common-mode choke) in accordance with some

embodiments of the disclosure. In some embodiments, Balun 800 suppresses common mode noise due to DC signal or due to electromagnetic induction. For example, if RF Rx 601 picks up unwanted charge, that unwanted charge is choked by Balun 800. In some embodiments, Balun 800 is implemented using mutual inductors LI and L2 and/or solenoids.

[0066] Referring back to Fig. 6, in some embodiments, LNA 603 is coupled to Balun

602 and STO apparatus 604. In some embodiments, LNA 603 amplifies the very weak signals captured by an antenna or RF Rx 601 and provided to LNA 603 via Balun 602.

Essentially, signals that are barely recognizable are amplified by LNA 603 without adding a lot of noise. LNA 603 has a low Noise Figure (NF). For example, LNA 603 has a NF of IdB (decibel) and a high gain (e.g., 20dB). [0067] Referring back to Fig. 6, STO apparatus 604 (e.g., apparatus

100/300/400/500) receives the amplified RF signal from LNA 603 and down converts it to IF signal with its built-in oscillator and mixer. In some embodiments, the IF signal is provided to DSP 605. Any known suitable DSP may be used for implementing DSP 605.

[0068] Fig. 9 illustrates an RF detection apparatus 900 for a wireless receiver having the 3T STO with built-in Mixer, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 9 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such. So as not to obscure the various embodiments, differences between Fig. 9 and Fig. 8 are described. In some embodiments, RF Rx coil 601 and Balun 602 are removed and replaced with Antenna 901.

[0069] In some embodiments, Antenna 901 may comprise one or more directional or omnidirectional antennas, including monopole antennas, dipole antennas, loop antennas, patch antennas, microstrip antennas, coplanar wave antennas, or other types of antennas suitable for transmission of RF signals. In some multiple-input multiple-output (MIMO) embodiments, Antenna(s) 901 are separated to take advantage of spatial diversity.

[0070] Fig. 10 illustrates apparatus 1000, with 3T STOs having built-in Mixers, showing parallel sensing using multiple receiver coils at a single frequency, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 10 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such.

[0071] In some embodiments, apparatus 1000 comprises a space division multiplexed signal array that includes antennas 1001 I N, STOS 101 I N, 102I-N, Isolators 103I N, and filters 1002I-N. Here, each antenna is coupled to an STO that generates an output RF signal COL- cok, and A(t) is the time domain amplitude, coiis the Larmor frequency or the center frequency of the receive signal band, and cok is the frequency division multiplexing (FDM) frequency. For example, antenna lOOl i is coupled to STO 1011 which provides an RF output signal to Bias T 102i.

[0072] In some embodiments, the output of Bias T 102i is received by Isolator 103i and then filtered by filter 1002i. The output of filter 1002i is then processed by a DSP logic. One reason for being able to form a parallel sensing apparatus 1000 is the small size of STO compared to transitional mixers with local oscillating clock sources. As such, many antennas with RF detection circuits (with STOs) can be used in a small form factor to detect and process data in parallel.

[0073] Fig. 11 illustrates apparatus 1100, with 3T STO having built-in Mixer, showing parallel sensing with frequency multiplexing, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 11 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such.

[0074] Compared to apparatus 1000, here frequency division multiplexing (FDM) is used to reduce the number of wires, in accordance with some embodiments. As such, an even smaller form factor is achievable than apparatus 1000. In some embodiments, each STO operates at a different oscillation frequency. For example, STO 1011 operates at coi, STO 10b operates at C02, and STON operates at CON, where 'N' is an integer greater than two. As such, the output of all STOs is a summation of RF signals with different frequencies.

[0075] In some embodiments, because each STO is tuned to operate at a different frequency, the same interconnect can be used to collect all RF signals output from the STOs. As such, the number of interconnects are reduced compared to apparatus 1000. In some embodiments, the frequency of each STO may be defined by the nature of the input RF signal. For example, for MRI, the center frequency is 64MHz to 128MHz, for cellular and adhoc wireless networks the center frequency is 500MHz to 3 GHz, and for millimeter wave, the center frequency is 60GHz. All these ranges are viable with STOs.

[0076] The RF signal's carrier frequency is the same for each input but the center oscillating frequency of the STOs is different by n x cok. In some embodiments, the IF signal goes to a bandpass filter where the center frequency of the bandpass filter in the IF output after the isolator is n x cok. In some embodiments, the signal is reconstructed in the DSP (this is done to create a higher power receive signal and thus higher S/N ratio). In some embodiments, the STOs 101 I N are tuned to the operating frequencies COI N via the feedback provided from the DC bias and control to Bias T 102.

[0077] In some embodiments, filters are used to detect the respective RF signal. In some embodiments, filters 1102I-N are centered at cok, 2cok, 3cok, . . Ncok, where 'N' is an integer greater than three. For example, filter 1 102i is used to detect RF signal having frequency coi, where coi = COL - cok, filter 1 102 _s is used to detect RF signal having frequency cos, where C02 = COL - 2cok, and filter 1 102N is used to detect RF signal having frequency CON, where C03 = COL - Ncok, where 'N' is an integer greater than two. In some embodiments, the filters can be present on the device near the STOs or can be in a remote location (i.e., away from the STOs). Any suitable filter can be used for implementing filters 1 102I-N.

[0078] Fig. 12 illustrates sensing array 1200 formed with the apparatus of Fig. 10, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 12 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such.

[0079] Sensing array 1200 applies the parallel sensing scheme of apparatus 1000.

Here, an MxN array is formed with antennas of RF Rx coils IOO INM and STOs IO INM tuned to a single frequency ω, where 'M' is the number of columns (e.g., 4) and 'N' is the number of rows (e.g., 5). In some embodiments, each column of sensing array 1200 results in 'N' number of wires that carry respective down converted RF (IF) signals for further processing. As such, sensing array 1200 generates MxN wires with MxN down converted IF signals for DSP logic 605 to process. The size of sensing array 1200 is small enough that it can fit in modern hand-held devices without having varacters and inductors, in accordance with some embodiments.

[0080] Fig. 13 illustrates sensing array 1300 formed with the apparatus of Fig. 11, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 13 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such.

[0081] Sensing array 1300 applies the parallel sensing scheme of apparatus 1 100. In some embodiments, RF signal can be collected via 'M' wires where each column is a frequency multiplexed arrangement of RF receivers. Compared to sensing array 1 100, sensing array 1200 has significantly fewer number of interconnects allowing for further reduction in the form factor of the arrays.

[0082] STO based RF detection described with reference to various embodiments allows for massively parallel RF detection comprising of detecting elements in excess of 1000 detectors. In comparison, the RF detection schemes used in the state of the art MRI is only limited to 24 channels. The STO based RF detection of the various embodiments also improves signal collection times for sensing. Sensing time is approximately proportional to l/(number of channels). The STO based RF detection of the various embodiments has a capability of being turned on the fly as required by the application or electromagnetic environment. For example, by adjusting the DC bias control to Bias T 102 and/or by adjusting the DC bias to SHE interconnect 403, operating frequency of the STO can be adjusted. Since the mixer and local oscillator functions are integrated in one device, the STO based RF detection of the various embodiments reduces the area of the RF detection scheme.

[0083] 14A illustrates an equivalent vector spin circuit model 1400 for STO RF detector 100 with locally generated oscillator, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 14A having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such.

[0084] STO 101 can be modeled using vector spin circuit theory comprising a 4x4 conduction matrix formulation for spin transport coupled with magnetization dynamics, in accordance with some embodiments. Model 1400 can be self-consistently coupled to the nano-magnet dynamics including the thermal stochastic noise effects, in accordance with some embodiments. The spin torque acting on the free layer in a spin-orbit torque MTJ 402 originates from spin torque due to spin injection from the fixed layer, and from spin torque due to the spin orbit torque acting on the free layer.

[0085] The phenomenological equation describing the dynamics of nanomagnets with the magnetic moment unit vector (m) is the modified Landau-Lifshitz-Gilbert-Slonczewski (LLG) equation expressed as:

where γ is the electron gyromagnetic ratio; ^ ₀ is the free space permeability; H _e ff (T is the effective magnetic field due to material, shape, and surface anisotropies, with the thermal noise component and 7 _s±m = (fh x in x I _s ) is the component of vector spin current perpendicular to the magnetization, and N _s is the total number of Bohr magnetons in the magnet. The dynamics of MTJ 402 are solved self-consistently with the spin transport in the equivalent circuit models.

[0086] The equivalent vector spin circuit for MTJ 402 comprises of the equivalent spin conductance of the fixed Ferromagnet (FMfi _xe d) and free Ferromagnet (FMfree) interfaces to form the MTJ 402. The vector spin equivalent circuit model for MTJ 402 is in model 1400. In some embodiments, model 1400 comprises of three nodes NO, Nl and N2 to describe MTJ 402. The RF input is applied to nodes 3 to 5 (or the low impedance configuration of Fig. 3. The IF output is collected across nodes 5 and 0, in accordance with some embodiments. [0087] The magnetization of the top fixed layer and the bottom free layer are described by m^ _i¾ and fhf _ree . The 4-component conductivity of the FM1 and oxide interface is described by GFMI and the conductivity of the FM2 and the oxide interface is described by GFM2. The conductance matrix describing the spin transport across a FM/Oxide interface can be written as:

where Gn is the interface conductivity (per interface) of the FM/MgO interface, a(V) is the spin polarization across the interface as a function of voltage, and GSL(VC) and GFL(VC) are Slonczewski and field like torque contributions from the tunneling spin current across the interface. The voltage dependence of spin polarization a(V), GSL(V), and GFL (V) is dependent on the detailed band structure of the electrodes and tunneling materials. The effect of magnetization rotation for a precessing MTJ 402 can be described using the proposed model, where the 4 component conductance evolve as a function of the magnetization of the free magnet.

G _FMO (M = R (mY ¹ G _FM0 (x)R< n)

where R (m) is a 4-component transformation to rotate the conductance matrices.

[0088] The spin torque from tunneling spin currents acting on the magnet and the effect of spin torque from spin orbit layer are included via a spin injection into the free layer as governed by the physics of spin injection from SHE layer 403 to FM layer. The equivalent spin circuit model includes a current control spin current to model the injection of spin current from SHE 403 to the free magnet layer. Here, the field like component of spin orbit torque is also added via a current controlled effective magnetic field due to spin orbit torque.

[0089] Fig. 14B illustrates plot 1420 showing the tunability of the STO, according to some embodiments of the disclosure. It is pointed out that those elements of Fig. 14B having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such. Here x-axis is Voltage (V) and y-axis is Frequency (GHz).

[0090] A simulation of the tunable spin torque dynamics of the SHE oscillator driven by the spin current response from a vector spin circuit model 1400 is shown by plot 1400. The vector magnetization dynamics of the free layer showing tunability of the local oscillator due to the combined action of anti-damping spin torque and effective field due to spin orbit effects is shown in plot 1420. An input RF signal centered at 10 GHz is shown in Fig. 2A, while the local oscillator dynamics are shown in the inset. The output of the RF detector across nodes 5 and 0 is shown in Fig. 2C. The simulations of Figs. 2A-C and Fig. 7B assume a 70 kT magnet with dimensions of 20 X 60 nm and with spin orbit metallic electrode of 60 X 60 nm of resistivity 200 μηι πι. In this simulation example, the bulk spin hall ratio is 0.15 and the effective Rashaba field is 8 x 10 ^"6 Oe/(A/cm ² ) for the transient vector spin simulations.

[0091] Fig. 15 illustrates a smart device or a computer system or a SoC (System-on-

Chip) with the 3T STO with built-in Mixer, according to some embodiments. It is pointed out that those elements of Fig. 15 having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such.

[0092] Fig. 15 illustrates a block diagram of an embodiment of a mobile device in which flat surface interface connectors could be used. In some embodiments, computing device 1600 represents a mobile computing device, such as a computing tablet, a mobile phone or smart-phone, a wireless-enabled e-reader, or other wireless mobile device. It will be understood that certain components are shown generally, and not all components of such a device are shown in computing device 1600.

[0093] In some embodiments, computing device 1600 includes first processor 1610 with the 3T STO with built-in Mixer as shown in apparatus 100/300/400/500, according to some embodiments discussed. Other blocks of the computing device 1600 may also include 3T STO with built-in Mixer as shown in apparatus 100/300/400/500, according to some embodiments. The various embodiments of the present disclosure may also comprise a network interface within 1670 such as a wireless interface so that a system embodiment may be incorporated into a wireless device, for example, cell phone or personal digital assistant.

[0094] In some embodiments, processor 1610 (and/or processor 1690) can include one or more physical devices, such as microprocessors, application processors,

microcontrollers, programmable logic devices, or other processing means. The processing operations performed by processor 1610 include the execution of an operating platform or operating system on which applications and/or device functions are executed. The processing operations include operations related to I/O (input/output) with a human user or with other devices, operations related to power management, and/or operations related to connecting the computing device 1600 to another device. The processing operations may also include operations related to audio I/O and/or display I/O.

[0095] In some embodiments, computing device 1600 includes audio subsystem

1620, which represents hardware (e.g., audio hardware and audio circuits) and software (e.g., drivers, codecs) components associated with providing audio functions to the computing device. Audio functions can include speaker and/or headphone output, as well as microphone input. Devices for such functions can be integrated into computing device 1600, or connected to the computing device 1600. In one embodiment, a user interacts with the computing device 1600 by providing audio commands that are received and processed by processor 1610.

[0096] In some embodiments, computing device 1600 comprises display subsystem

1630. Display subsystem 1630 represents hardware (e.g., display devices) and software (e.g., drivers) components that provide a visual and/or tactile display for a user to interact with the computing device 1600. Display subsystem 1630 includes display interface 1632, which includes the particular screen or hardware device used to provide a display to a user. In one embodiment, display interface 1632 includes logic separate from processor 1610 to perform at least some processing related to the display. In one embodiment, display subsystem 1630 includes a touch screen (or touch pad) device that provides both output and input to a user.

[0097] In some embodiments, computing device 1600 comprises I/O controller 1640.

I/O controller 1640 represents hardware devices and software components related to interaction with a user. I/O controller 1640 is operable to manage hardware that is part of audio subsystem 1620 and/or display subsystem 1630. Additionally, I/O controller 1640 illustrates a connection point for additional devices that connect to computing device 1600 through which a user might interact with the system. For example, devices that can be attached to the computing device 1600 might include microphone devices, speaker or stereo systems, video systems or other display devices, keyboard or keypad devices, or other I/O devices for use with specific applications such as card readers or other devices.

[0098] As mentioned above, I/O controller 1640 can interact with audio subsystem

1620 and/or display subsystem 1630. For example, input through a microphone or other audio device can provide input or commands for one or more applications or functions of the computing device 1600. Additionally, audio output can be provided instead of, or in addition to display output. In another example, if display subsystem 1630 includes a touch screen, the display device also acts as an input device, which can be at least partially managed by I/O controller 1640. There can also be additional buttons or switches on the computing device 1600 to provide I/O functions managed by I/O controller 1640.

[0099] In some embodiments, I/O controller 1640 manages devices such as accelerometers, cameras, light sensors or other environmental sensors, or other hardware that can be included in the computing device 1600. The input can be part of direct user interaction, as well as providing environmental input to the system to influence its operations (such as filtering for noise, adjusting displays for brightness detection, applying a flash for a camera, or other features).

[00100] In some embodiments, computing device 1600 includes power management

1650 that manages battery power usage, charging of the battery, and features related to power saving operation. Memory subsystem 1660 includes memory devices for storing information in computing device 1600. Memory can include nonvolatile (state does not change if power to the memory device is interrupted) and/or volatile (state is indeterminate if power to the memory device is interrupted) memory devices. Memory subsystem 1660 can store application data, user data, music, photos, documents, or other data, as well as system data (whether long-term or temporary) related to the execution of the applications and functions of the computing device 1600.

[00101] Elements of embodiments are also provided as a machine-readable medium

(e.g., memory 1660) for storing the computer-executable instructions (e.g., instructions to implement any other processes discussed herein). The machine-readable medium (e.g., memory 1660) may include, but is not limited to, flash memory, optical disks, CD-ROMs, DVD ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, phase change memory (PCM), or other types of machine-readable media suitable for storing electronic or computer- executable instructions. For example, embodiments of the disclosure may be downloaded as a computer program (e.g., BIOS) which may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) by way of data signals via a communication link (e.g., a modem or network connection).

[00102] In some embodiments, computing device 1600 comprises connectivity 1670.

Connectivity 1670 includes hardware devices (e.g., wireless and/or wired connectors and communication hardware) and software components (e.g., drivers, protocol stacks) to enable the computing device 1600 to communicate with external devices. The computing device 1600 could be separate devices, such as other computing devices, wireless access points or base stations, as well as peripherals such as headsets, printers, or other devices.

[00103] Connectivity 1670 can include multiple different types of connectivity. To generalize, the computing device 1600 is illustrated with cellular connectivity 1672 and wireless connectivity 1674. Cellular connectivity 1672 refers generally to cellular network connectivity provided by wireless carriers, such as provided via GSM (global system for mobile communications) or variations or derivatives, CDMA (code division multiple access) or variations or derivatives, TDM (time division multiplexing) or variations or derivatives, or other cellular service standards. Wireless connectivity (or wireless interface) 1674 refers to wireless connectivity that is not cellular, and can include personal area networks (such as Bluetooth, Near Field, etc.), local area networks (such as Wi-Fi), and/or wide area networks (such as WiMax), or other wireless communication. In some embodiments, Connectivity 1670 includes parallel sensing arrays as described with reference to Figs. 10-13.

[00104] In some embodiments, computing device 1600 comprises peripheral connections 1680. Peripheral connections 1680 include hardware interfaces and connectors, as well as software components (e.g., drivers, protocol stacks) to make peripheral connections. It will be understood that the computing device 1600 could both be a peripheral device ("to" 1682) to other computing devices, as well as have peripheral devices ("from" 1684) connected to it. The computing device 1600 commonly has a "docking" connector to connect to other computing devices for purposes such as managing (e.g., downloading and/or uploading, changing, synchronizing) content on computing device 1600. Additionally, a docking connector can allow computing device 1600 to connect to certain peripherals that allow the computing device 1600 to control content output, for example, to audiovisual or other systems.

[00105] In addition to a proprietary docking connector or other proprietary connection hardware, the computing device 1600 can make peripheral connections 1680 via common or standards-based connectors. Common types can include a Universal Serial Bus (USB) connector (which can include any of a number of different hardware interfaces), DisplayPort including MiniDisplayPort (MDP), High Definition Multimedia Interface (HDMI), Firewire, or other types.

[00106] Reference in the specification to "an embodiment," "one embodiment," "some embodiments," or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of "an embodiment," "one embodiment," or "some embodiments" are not necessarily all referring to the same embodiments. If the specification states a component, feature, structure, or characteristic "may," "might," or "could" be included, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, that does not mean there is only one of the elements. If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[00107] Furthermore, the particular features, structures, functions, or characteristics may be combined in any suitable manner in one or more embodiments. For example, a first embodiment may be combined with a second embodiment anywhere the particular features, structures, functions, or characteristics associated with the two embodiments are not mutually exclusive.

[00108] While the disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of such embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. The embodiments of the disclosure are intended to embrace all such alternatives, modifications, and variations as to fall within the broad scope of the appended claims.

[00109] In addition, well known power/ground connections to integrated circuit (IC) chips and other components may or may not be shown within the presented figures, for simplicity of illustration and discussion, and so as not to obscure the disclosure. Further, arrangements may be shown in block diagram form in order to avoid obscuring the disclosure, and also in view of the fact that specifics with respect to implementation of such block diagram arrangements are highly dependent upon the platform within which the present disclosure is to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that the disclosure can be practiced without, or with variation of, these specific details. The description is thus to be regarded as illustrative instead of limiting.

[00110] The following examples pertain to further embodiments. Specifics in the examples may be used anywhere in one or more embodiments. All optional features of the apparatus described herein may also be implemented with respect to a method or process. [00111] For example, an apparatus is provided which comprises: a magnetic junction device having a magnetic layer with in-plane anisotropy and a magnetic layer with perpendicular anisotropy; a spin orbit coupling (SOC) layer coupled to the magnetic junction device; a first non-magnetic conductor coupled to one end of the SOC layer; a second nonmagnetic conductor coupled to another end of the SOC layer; a third non-magnetic layer coupled to the magnetic junction device; and a bias T network coupled to the third nonmagnetic layer.

[00112] In some embodiments, the magnetic layer with in-plane anisotropy is a free magnetic layer and the magnetic layer with perpendicular anisotropy is a fixed layer, and wherein the magnetic layer with in-plane anisotropy is coupled to the SOC layer. In some embodiments, the magnetic layer with in-plane anisotropy is a fixed magnetic layer the magnetic layer with perpendicular anisotropy is a free magnetic layer, and wherein the magnetic layer with perpendicular anisotropy is coupled to the SOS layer. In some embodiments, the SOC layer is formed of one or more of: β-Ta, β-W, W, Pt, Cu doped with Iridium, Cu doped with Bismuth, or Cu doped with an element of 3d, 4d, 5d, 4f, or 5f of periodic table groups.

[00113] In some embodiments, the magnetic layers are formed of one of: a Heusler alloy, Co, Fe, Ni, Gd, B, Ge, Ga, or a combination of them. In some embodiments, the magnetic layer with perpendicular anisotropy is formed of a stack of materials, wherein the stack is at least one of: Co and Pt; Co and Pd; Co and Ni; MgO, CoFeB, Ta, CoFeB, and MgO; MgO, CoFeB, W, CoFeB, and MgO; MgO, CoFeB, V, CoFeB, and MgO; MgO, CoFeB, Mo, CoFeB, and MgO; Mn _x Ga _y ; Materials with L10 symmetry; or materials with tetragonal crystal structure. In some embodiments, the magnetic layer with perpendicular anisotropy is formed of a single layer of one or more materials. In some embodiments, the single layer is formed of MnGa.

[00114] In some embodiments, the apparatus further comprises an isolator coupled to the bias T network. In some embodiments, the apparatus comprises a digital signal logic coupled to the isolator and the second non-magnetic conductor. In some embodiments, the apparatus comprises a low noise amplifier (LNA) coupled to the first and third non-magnetic conductors. In some embodiments, the apparatus comprises a balun coupled to the LNA. In some embodiments, the apparatus comprises an antenna coupled to the LNA. In some embodiments, the apparatus comprises a radio frequency (RF) receiver coil or antenna coupled to the balun. [00115] In some embodiments, the RF receiver coil includes a detuning circuit for adjusting a center frequency. In some embodiments, the RF receiver coil includes pairs or inductors and capacitors coupled together in a ring orientation. In some embodiments, the magnetic junction device and the SOC layer together form a three terminal (3T) device which is an oscillator with built-in mixer. In some embodiments, the bias T network is operable to bias the magnetic junction through the third non-magnetic conductor to adjust a center frequency of oscillation of the oscillator. In some embodiments, the SOC layer is operable to be biased to adjust a center frequency of oscillation of the oscillator.

[00116] In some embodiments, the 3T device has high input impedance across the first and third non-magnetic conductors. In some embodiments, the 3T device has low input impedance across the first and second non-magnetic conductors. In some embodiments, the oscillator with built-in mixer provides an oscillating output across the third and second nonmagnetic conductors independent of an oscillating input.

[00117] In another example, a system is provided which comprises: a memory; a processor coupled to the memory, and a wireless interface for allowing the processor to communicate with another device, wherein the wireless interface has an apparatus according to the apparatus described above.

[00118] In another example, an apparatus is provided which comprises: an array of antennas; and an array of oscillators with built-in mixers, wherein each antenna of the array of antennas is coupled to an oscillator with built-in mixer forming a pair, wherein at least one oscillator with built-in mixer is formed with a magnetic junction and a spin orbit coupling (SOC) layer, and wherein at least one pair has an associated interconnect coupled to a corresponding bias T network. In some embodiments, at least one oscillator with built-in mixer provides an oscillating output independent of an oscillating clock input.

[00119] In some embodiments, the apparatus comprises: an array of isolators, wherein at least one isolator is coupled to the corresponding bias T network; and an array of filters, wherein at least one filter of the array of filters is coupled to one of the isolators of the array of isolators. In some embodiments, the array of antennas and the array of oscillators are configured as a space division multiplexed signal array.

[00120] In another example, a system is provided which comprises: a memory; a processor coupled to the memory, and a wireless interface for allowing the processor to communicate with another device, wherein the wireless interface has an apparatus according to the apparatus described above. [00121] In another example, an apparatus is provided which comprises: an array of antennas; and an array of oscillators with built-in mixers, wherein each antenna of the array of antennas is coupled to an oscillator with built-in mixer forming a pair, wherein at least one oscillator with built-in mixer is formed with a magnetic junction and a spin orbit coupling (SOC) layer, and wherein at least two pairs are coupled to a shared interconnect which in turn is coupled to a bias T network.

[00122] In some embodiments, at least one oscillator with built-in mixer provides an oscillating output independent of an oscillating clock input. In some embodiments, the apparatus comprises: an isolator coupled to the shared bias T network; and an array of filters coupled to the isolators. In some embodiments, the array of antennas and the array of oscillators are configured as a frequency division multiplexed signal array.

[00123] In another example, a system is provided which comprises: a memory; a processor coupled to the memory, and a wireless interface for allowing the processor to communicate with another device, wherein the wireless interface has an apparatus according to the apparatus described above.

[00124] In another example, an apparatus is provided which comprises: a parallel radio-frequency (RF) sensing array with a plurality of antennas, wherein at least one antenna is coupled to an apparatus to the apparatus described above.

[00125] In another example, a method is provided which comprises: receiving a radio frequency (RF) signal; and down converting the RF signal to an intermediate frequency (IF) to generate an output signal without a clock signal. In some embodiments, the method comprises: providing a first DC bias to a top electrode of a magnetic junction; and providing a second DC bias to a spin orbit coupling (SOC) layer coupled to the magnetic junction, wherein the SOC layer is to receive the RF signal.

[00126] In another example, an apparatus is provided which comprises: means for receiving a radio frequency (RF) signal; and means for down converting the RF signal to an intermediate frequency (IF) to generate an output signal without a clock signal. In some embodiments, the apparatus comprises: means for providing a first DC bias to a top electrode of a magnetic junction; and means for providing a second DC bias to a spin orbit coupling (SOC) layer coupled to the magnetic junction, wherein the SOC layer is to receive the RF signal.

[00127] In another example, a system is provided which comprises: a memory; a processor coupled to the memory, and a wireless interface for allowing the processor to communicate with another device, wherein the wireless interface has an apparatus according to the apparatus described above.

[00128] An abstract is provided that will allow the reader to ascertain the nature and gist of the technical disclosure. The abstract is submitted with the understanding that it will not be used to limit the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.