A 256–287 GHz Full 360° Hybrid-type Phase Shifter with Active SPDT Switches

This paper presents a WR-3.4-band phase shifter in a 250-nm InP double heterojunction bipolar transistor (DHBT) technology. By combining a 180° reflection-type phase shifter (RTPS) and 1-bit switching-type phase shifter (STPS), the proposed phase shifter achieves a continuous full 360° phase shift range. The STPS includes two active single-pole double-throw (SPDT) switches designed using a two-stage common-base topology. This compensates for high insertion loss of the passive RTPS. In addition, the 1-bit 180° phase delay is implemented by switching between pi-type low-pass and high-pass structures for minimizing the amplitude and phase imbalance over a wide frequency range. The measurement shows that the phase shifter provides a continuous full 360° phase shift with an average insertion loss of 5.6–8.6 dB over a frequency range from 256 to 287 GHz. The RMS amplitude and phase errors are 2.3 dB and 4.4°, respectively, at 270 GHz.