Ultra-wideband 180° active digital phase-shifting unit design

In this paper, an ultra-wideband active phase shifter circuit structure based on GaAs pHEMT process is adopted to design a 180° phase shifting unit for a 4~18GHz ultra-wideband active CNC phase shifter. The design uses the topology of the active Balun circuit combined with the SPDT switch. The active Balun structure widens the operating band while compensating for the low-frequency insertion loss difference. The design also optimizes the insertion loss and area of the phase shifter by improving the switching circuit. Simulation results show that the 180° active phase shifter unit has an insertion loss range of 3.33 to 5.4dB, amplitude fluctuation of each state is less than 1.5dB, phase shift accuracy is 180±2.5°, input, and output return loss is less than 10dB, and chip area is 1.9mm*1.0mm.