An X- and Ku-band 7 bit Active Differential Phase Shifter

In this paper, an X- and Ku-band 7bit digital active differential phase shifter with current vector-sum is proposed to achieve high resolution and low error. The phase shifter is implemented in 0.13μm SiGe BiCMOS process. Two orthogonal vector signals are generated by a quadrature all-pass filter (QAF) network with resistance compensation, and the vector modulator is composed of two Gilbert cell array circuits with current-steering. In addition, digital control signals are designed with redundant bits to enhance accuracy. The simulation results demonstrate that within the frequency range of 8 ~ 16 GHz, the phase shifter exhibits a RMS phase error of less than 2° for 128 states. Additionally, the RMS amplitude error is less than 0.6 dB, the gain is maintained between -1.5 dB and 1 dB, the input return loss is less than -10 dB, and the output return loss is less than -9 dB.