To provide a varactor shunt switch with low loss which is suitable for use in microwave frequencies.
Nanostructured BST thin-films with dielectric tunability as high as 4.3:1 can be obtained on sapphire substrates 100, with very low loss-tangents below 0.025 at zero-bias and 20 GHz. The large capacitance of the varactor at zero bias can shunt the input signal to ground isolating the output port, resulting in the OFF state. When applying a bias voltage of approximately 10 V, the varactor's capacitance can be reduced to a minimum, allowing maximum transmission to the output resulting in the ON state. The microwave switching performance of the varactor shunt switch 10 can be compared with the RF MEMS switches for potential applications at microwave and millimeterwave frequencies. Other applications of such BST varactors include tunable filters, phase shifter circuits and impedance matching circuits.
COPYRIGHT: (C)2010,JPO&INPIT
Kazuo Shamoto
Yasushi Kobayashi
Akio Chiba
Hiroyuki Tomita
Tadashi Ueda
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