A full-range all-pass variable phase shifter for multiple antenna receivers

A fourth-order all-pass variable phase shifter achieves a total phase shift range greater than 360/spl deg/ in a 10.35-10.8 GHz band of frequencies for multiple-antenna receiver applications. A cascode biasing technique is used to halve power consumption compared to conventional approaches and the variable phase shifter is optimized using a parasitic-aware particle-swarm optimization paradigm. Simulation results show power gain of 1.4/spl plusmn/0.7 dB, return loss less than -15 dB and minimum IIP3 of -3 dBm in a 250 nm SiGe HBT process.