High frequency solid state switching for impedance matching

摘要

In accordance with this invention the above and other problems are solved by a switching apparatus and method that uses a switching circuit having a pair of parallel solid-state diodes (e.g., PN or PIN diodes), one of which is connected to a transistor (e.g., power MOSFET or IGBT), to switch a capacitor (or reactance element) in or out of a variable capacitance element (or variable reactance element) of an impedance matching network. Charging a body capacitance of the transistor reverse biases one of the two diodes so as to isolate the transistor from the RF signal enabling a low-cost high capacitance transistor to be used. Multiple such switching circuits and capacitors (or reactance elements) are connected in parallel to provide variable impedance for the purpose of impedance matching.

主权项

1. A circuit of a variable reactance element of an impedance matching network comprising:
a reactance element coupled between a first voltage line and a first node; a first diode having an anode coupled to the first node and a cathode coupled to a second node; a second diode having an anode to couple to a second voltage line and a cathode to couple to the first node; a transistor having a first, second, and control terminals, wherein:
the first terminal is coupled to the second node;the second terminal is coupled to the second voltage line;the control terminal is coupled to a controller; andthe reactance element is switched into the variable reactance element when the transistor is on and switched out after the transistor is off.