Microwave field effect switch

Abstract

A monolithic microwave integrated circuit switch includes a series field effect transistor having a source drain path in series with an inductive transmission line including plural taps. Source drain paths of plural shunt field effect transistors are connected to the taps. The source drain paths of the series and shunt transistors are biased so that the series and shunt source drain paths have complementary low and high impedance states. The high impedance state is capacitive, having a value on the order of magnitude of the inductive transmission line. During a first time interval, the capacitive and inductive impedances form a matched low pass filter to supply current from a microwave source to a load. During a second time interval, current from the microwave source flows through the shunt field effect transistors to be decoupled from the load. The circuit is in stripline form, with source electrodes of field effect transistors including first and second arms respectively having first and second elongated parallel sides. First and second elongated edges of drain electrodes of the transistors extend parallel to the elongated sides. A gate electrode of each transistor includes first and second elongated fingers respectively extending parallel the elongated sides and edges. The first finger is between the first side and first edge; the second finger is between the second side and second edge.