An SPDT Switch Design Featuring Minimum Phase Distortion Over Wide Input Power Drive for Phased-Array Antenna System Applications

RF switch is an essential component for phased- array antennas in modern communication systems. The series-shunt configuration is preferable due to the balanced performance of high isolation and power handling capability. Conventionally, such configuration suffered from phase fluctuations over the input power drive making extra phase compensation necessary for proper system operation. Theoretical analysis by an equivalent circuit model revealed that the phase fluctuation was primarily caused by the capacitance of the devices in the series arm. We thus proposed a design using the single-pole-double-throw (SPDT) configuration as an example featuring minimum phase variation over a very wide RF input power range. Compared to the conventional one, the proposed design achieved at least a reduction of over 10 degrees at 28 GHz in phase variation over a wide input power range up to the input 1-dB compression point (P-1 dB). To our knowledge, this is the first series-shunt type SPDT switch study achieving the minimum phase variation over wide input power levels.