an amplifier comprising the same

Technical field

The invention relates to power components, especially relates to a selection circuit which can reduce power loss and an amplifier comprising the selection circuit.

Background

The efficiency of a power amplifier always decreases along with its output power less than its power rating. In order to optimizing the efficiency of a power amplifier according to changes of its output power, when the output power of a power amplifier is less than its power rating, it' s common to decrease the voltage and current of the drain/collector electrode so as to compensate the worsen efficiency with some method. But the performance of a power amplifier will limit the decrease degree of offset voltage and current, thus the method can't solve the above problem completely.

At present, the Doherty power amplifier (DPA) often used, especially asymmetrical DPA and multilevel DPA can maintain an accepted power amplifier efficiency in condition of high level of reverse power. But there's the same problem as described above in DPA too, that's the efficiency of DPA is getting worse along with its output power less than its power rating. The design difficulty (high reverse) and cost (multipath DPA) make solving the above problems with difficulties. Summary of invention

The invention proposes one solution of solving the above problems, that's, it relates to a selection circuit which can reduce power loss and an amplifier comprising the selection circuit.

According to the first aspect of the invention, it proposes a selection circuit, comprising: at least one power division phase shift module having a first input, a second input, a first output and a second output, wherein the at least one power division phase shift module is used for transforming the power signal inputted into the first input and/or the second input into two orthogonal power signals with the same amplitude outputted by the first output and the second output, and the power division phase shift module comprises at least one 3dB 90° hybrid; a first transmission line module connecting the first input to a first input port of the selection circuit; a second transmission line module connecting the second input to a second input port of the selection circuit; a third transmission line module connecting the first output to the second input; a first switch module used for grounding the second input port; and a second switch module used for grounding the first output .

Using the selection circuit of the invention, one or two power amplifiers may be selected dynamically to work according to the change of the output power. Thus the efficiency of the power amplifiers can be kept almost constant and the performance of the power amplifiers won't be affected.

The selection circuit of the invention may work in a first working state and a second working state.

In the first working state, the first input port is used for receiving a first power signal, and the second input port is used for receiving a second power signal, and wherein the first power signal and the second power signal are orthogonal and have the same amplitude, and the first switch module is open and the second switch module is closed, the first power signal passes through the first transmission line module, and the second power signal passes through the second transmission line module, and the first power signal is inputted into the first input of the power division phase shift module, the second power signal is inputted into the second input of the power division phase shift module, a power signal superimposed is outputted by the second output of the power division phase shift module as output power signal of the circuit, and the first output of the power division phase shift module has no output power signal .

In the first working state, if the external power need is full power need, that's, the external power need is almost equal to the superimposition of the first power signal and the second power signal, the circuit can fully use the first power signal and the second power signal to reduce the power loss.

In the second working state, the first input port is used for receiving the first power signal, and the first switch module is closed and the second switch module is open, the first power signal passes through the first transmission line module, and the first power signal is inputted into the first input of the power division phase shift module, and at least part of the inputted first power signal feeds back to the second input of the power division phase shift module via the third transmission line module, and a power signal is outputted by the second output of the power division phase shift module.

In the second working state, if the external power need is half power need, that's, the external power need is almost equal to the first power signal or the second power signal, in the present art one load will be added at the output port of the power division phase shift module connected with transmission line to absorb the output power in the output port. While the invention makes an improvement which changes the load in present art into a feedback circuit using transmission line to connect the output port and input port of the power division phase shift module. The feedback circuit will feed back continuously the output power signal of the power division phase shift module that is absorbed by the load in the present art to the input port of the power division phase shift module. Finally the first power signal amplified is outputted by the other output port of the power division phase shift module to avoid the part of power loss absorbed by the load.

Preferably, the first switch module and the second switch module comprise at least one PIN diode which has advantages of small size and low cost as semiconductor components . PIN diodes has more ideal switching characteristic especially in high frequency signal application .

Preferably, the transmission line module is a quarter-wave transmission line. The quarter-wave transmission line is especially suitable for high frequency application.

Preferably, the first input port and the second input port of the selection circuit are used for receiving high frequency power signal. The embodiment can be applied high frequency power amplifier such as that of communication devices to get higher amplifier efficiency .

An amplifier circuit is proposed according to the second aspect of the invention, wherein comprises: a selection circuit according to the first aspect of the invention; a first amplifier with an output connected to the first input port of the selection circuit; and a second amplifier with an output connected to the second input port of the selection circuit; wherein the selection circuit is used for selecting, as the output of the amplifier circuit, the output of the first amplifier or a superposition of the output of the first amplifier and the second amplifier.

Using the amplifier circuit of the invention, one or two power amplifiers may be selected dynamically to work according to the change of the output power. Thus the efficiency of the power amplifiers can be kept almost constant and the performance of the power amplifiers won't be affected.

An amplifier device is proposed according to the third aspect of the invention, wherein comprises: an amplifier circuit according to the second aspect of the invention; and a power division phase shift module having a first input, a second input, a first output and a second output, wherein the first input is used for receiving the signal to be amplified, and the first output is used for connecting the input of the first amplifier, and the second output is used for connecting the input of the second amplifier.

Using the amplifier device of the invention, one or two power amplifiers may be selected dynamically to work according to the change of the output power. Thus the efficiency of the power amplifiers can be kept almost constant and the performance of the power amplifiers won't be affected.

An amplifier system is proposed according to the fourth aspect of the invention, wherein comprising at least two amplifier devices connected in parallel according to the third aspect of the invention.

Using the amplifier device of the invention, one or 2 ^N (N=1,2,3 ) power amplifiers may be selected dynamically to work according to the change of the output power. Thus the efficiency of the power amplifiers can be kept almost constant and the performance of the power amplifiers won't be affected. Description of figures

The characteristics, purpose and advantages of the invention can be easily understood by referring to the figures and reading the following detailed description of the unlimited embodiments. Wherein the same or similar figure marks represent the same or similar devices.

Fig.l illustrates the circuit topological graph of the amplifier device working in the first working state in the first embodiment according to the invention;

Fig.2 illustrates the circuit topological graph of the amplifier device working in the second working state in the first embodiment according to the invention;

Fig.3 illustrates the circuit topological graph of the amplifier system in the second embodiment according to the invention.

Detailed description of the embodiments

The following is detailed description of the embodiment realizing the invention.

Fig.l illustrates the circuit topological graph of the amplifier device working in the first working state according to the first embodiment of the invention. It also illustrates the structure of the amplifier devicelOO of the embodiment, comprising: three transmission lines 160,170 and 180, two 3dB hybrids 120 and 130, two power amplifiers 140 and 150, and two PIN diodes 190 and 191. Wherein, the 3dB 90°hybrid 130 has a first input, a second input, a first output and a second output and is used for transforming the power signal inputted into the first input and/or the second input into two orthogonal power signals with the same amplitude outputted by the first output and the second output; The transmission line 160 connects the first input and the output of the power amplifier 140; The transmission line 170 connects the second input and the output of the amplifier 150; The transmission line 180 connects the first output and the second input; The PIN diode 190 connects the second input to the ground and the PIN diode 191 connects the first output to the ground; The 3dB 90°hybrid 120 has a first input, a second input, a first output and a second output, the first input port is used for connecting the signal to be amplified, the first output port connects the input port of the amplifier 140, the second output port connects the input port of the amplifier 150.

When it is needed that the output power is equal to the power rating, the amplifier device 100 of the invention works in the first working state. Now both of the amplifiers 140 and 150 are working, the high frequency power signal SI is inputted from the input 110, goes through the 3dB hybrid 120 and is transformed into two orthogonal power signals with the same amplitude at the 3dB hybrid 120. The two power signals are inputted into the inputs of two power amplifiers 140 and 150 separately and the two amplified power signals are outputted by their output ports after amplified. Since now the PIN diode 190 is open and the PIN diode 191 is closed, and due to the closed and open characteristic of transmission line, one end of the transmission line 180 is closed by the PIN diode 191 and the other end of the transmission line 180 can be considered as being open, that' s, the feedback circuit between the input port and output port of 3dB 90° hybrid 130 connected by the transmission line 180 con be considered not exist . Now, the two orthogonal amplified power signals with the same amplitude still keep the two orthogonal power signals with the same amplitude after going through the transmission line 160 and 170, then are inputted into two inputs of 3 dB 90° hybrid 130 respectively, and the combined power of the two power signals is outputted at the output port 111.

In the first working state, both of the two power amplifiers 140 and 150 work, the external power need is almost equal to the combined power of power signals of two amplifiers outputted by the output port 111. The efficiency of power amplifiers can be kept higher. And the performance of power amplifiers isn't affected due to the using of PIN diodes with good switch performance in high frequency as switch components.

Fig.2 illustrates the circuit topological graph of the amplifier device working in the second working state in the first embodiment according to the invention. When it's needed that the output power is half of the power rating, the amplifier device of the first embodiment of the invention works in the second working state. The amplifier device 100 of the embodiment comprises : three transmission lines 160, 170 and 180, two 3dB 90° hybrids 120 and 130, two power amplifiers 140 and 150, and two PIN diodes 190 and 191. When it's needed that the output power is half of the power rating, the amplifier device 100 of the invention works in the second working state. Now only one amplifier works, that's, the amplifier 140 works and the amplifier 150 is open. The high frequency power signal S2 is inputted from the input port 110, passes 3dB 90° hybrid 120, and is transformed into two orthogonal power signals with the same amplitude at two output ports of the 3dB hybrid 120. The first of the two power signals is inputted into the input port of the power amplifier 140 and the second is partially reflected to the input port of the 3dB hybrid 120 such that it is consumed. Since at this time the power signal isn't amplified, the power consumption is very limited.

The first power signal is amplified by the amplifier 140 and outputs the amplified power signal at the output port. Since now the PIN diode 190 is closed and the PIN diode 191 is open, and due to the closed and open characteristic of transmission line, one end of the transmission line 170 connected with the PIN diode 190 is closed and the other port of the transmission line 170 can be considered as being open, that's, the feedback circuit between the input and output of the 3dB 90° hybrid 130 is connected by the transmission line 180. Now the first power signal amplified is inputted into one input of the 3dB 90° hybrid 130 after passing through the transmission line 160 and is outputted by the two outputs of the 3dB 90° hybrid 130. While the power signal outputted by the output connected with the transmission line 180 will be continuously fedback to the input port via the transmission line 180, and finally the amplified first power signal is outputted by the output port 111.

In the second working state, only one power amplifier 140 works .

In the present art one load will be added at the output of the 3dB 90° hybrid 130 connected with the transmission line 180 to absorb the output power of the output port, while the invention makes an improvement that the load in the present art is changed into the feedback circuit which connects the output 112 and the input 113 via the transmission line 180. The feedback circuit continuously feeds back the power signal outputted by the output 112 that is absorbed by the load in the present art to the input 113. Finally the first amplified power signal is outputted by the output 111 to avoid the loss of partial power absorbed by the load. Now the amplifier device of the invention can still ensure that the external power need is almost equal to the power signal outputted by the output 111. Therefore the efficiency of power amplifier can be kept higher. The performance of power amplifiers isn't affected due to the using of PIN diodes with good switch performance in high frequency as switch components.

It is to be noted that the embodiment isn't only limited to amplifying high frequency power signals. It's applicable for intermediate frequency, low frequency power signals too, just needing to do corresponding modification in the selection of specific components of circuits. And the specific components selected in the embodiment are not the only scheme to implement the invention, e.g. the 3dB 90° hybrid may be implemented by a combination of a power divider and a 90 phase shifter or other standalone circuits with functions of dividing power and 90 phase shift etc., PIN diodes may be implemented by other switch components or switch circuits, e.g. transistors or high-power switches or other integrated or standalone circuits with switch function etc.

Fig.3 illustrates the circuit topological graph of the amplifier system in the second embodiment according to the invention. The amplifier system 300 comprises 2 ^N ( N=l , 2 , 3 )power amplifiers, every two power amplifiers consist of one level 1 unit 310 of one basic amplifier device, two units 310 of the basic amplifier device can consist of one level 2 unit 320 comprising four power amplifiers, two level 2 units further consist of one level 3 unit 330 comprising eight power amplifiers, and so on, two level N-l units can consist of one level N unit comprising 2 ^N (N=l,2,3 ) power amplifiers, wherein the specific topology of the amplifier device unit 310 may be the amplifier device in the first embodiment . The amplifier system consisted of level N units comprising 2 ^N ( N=l , 2 , 3 ) power amplifier has N+l ( N=l , 2 , 3 ) workingstatewithl, 2, 4 , , 2 ^N power amplifiers working respectively. E.g., when external power need is just right output power P of one power amplifier working, the amplifier system only needs one power amplifier working to meet the external power need and keep higher amplifier efficiency; When external power need changes to 2P, the amplifier system need two power amplifiers working to meet the external power need and still keep higher amplifier efficiency; In like manner, when external power need changes to 4P, the amplifier system need four power amplifiers working to meet the external power need and still keep higher amplifier efficiency;

When external power need changes to 2 ^N *P (N=l, 2, 3 ) , the amplifier system need 2 ^N (N=l,2,3 ) power amplifiers working to meet the external power need and keep higher amplifier efficiency. Since in the procedure it's always ensured that external power need is almost equal to the power rating of the amplifier system, it's always ensured that keeping higher and constant amplifier efficiency. And the performance of power amplifiers isn't affected due to the using of PIN diodes with good switch performance in high frequency as switch components. Obviously the amplifier system of the embodiment has good adaptability and flexibility, and designing N value and/or selecting power amplifier may be based on the specific application environment .

Though the invention has been described referring to the present considered embodiments, it should be understood that the invention isn't limited to the disclosed embodiments. On the contrary, the invention is intended to cover all kinds of modification and equal arrangement falling into the spirit and scope of the claims attached. The scope of claims meets the widest explanation to contain all such modification and equal structures and functions.