US Patent 9065426 High frequency solid state switching for impedance matching

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.