A 23-30 GHz Variable-Gain Phase Shifter Exploiting X-Type Attenuator Array

A Ka-band variable gain phase shifter (VGPS) based on a 55 nm SOI CMOS process is proposed in this paper. It consists of a quadrature signal generator and an X-type attenuator array. The X-type attenuator array features two distinct control schemes for phase and amplitude tuning of the circuit, respectively. Additionally, a complementary control voltage for the X-type attenuator array is developed to minimize impedance variations across different attenuation levels. The post-layout simulation results demonstrate that the VGPS achieves a full 360° phase tuning range with a resolution of 5.625° and supports a 12.3 dB gain tuning range over the 23-30 GHz frequency band. At 27 GHz, the proposed VGPS exhibits an insertion loss of 12.5 dB. The core circuit only occupies 0.25 mm² chip area.