An L-band 5-bit differential active phase shifter utilizing a phase shifting performance of RC filter circuits

An L-band 5-bit differential active phase shifter using a phase shifting performance of RC filter circuits is presented. It employs R or RC filter circuits in the series feedback loop of the differential amplifiers and achieves 90deg, 45deg, 22.5deg, and 11.25deg of phase shift by switching on and off the R or RC filter circuits alternatively. On the other hand, a 180deg of phase shift is achieved with the use of a phase difference between the differential outputs. By cascading all five bits, an insertion gain of 13 to 19 dB and an RMS phase error of 7.2deg have been achieved at 1 GHz.