Analysis and Design of a Ku-Band Bidirectional Time-Varying Vector-Sum Phase Shifter in 0.13-μm CMOS Technology

This brief describes a Ku-band passive time-varying phase shifter (TVPS). The time variable is introduced into the conventional vector-sum phase shifter (VSPS) architecture, and the time-varying vector-sum method is proposed for the first time to realize continuous phase shifting. The proof-of-concept passive TVPS consisting of a quadrature coupler, two 0/180° bi-phase modulators and an output combiner is implemented in 0.13- $\mathbf {\mathrm {\mu }}\text{m}$ CMOS technology with a core area of 2.2 $\mathbf {\times }$ 0.8 mm2, and a field-programmable gate array (FPGA) is used to provide gain-control timing sequences with the modulation frequency of 100 kHz for its four control bits. The timing sequences are optimized to eliminate unwanted sidebands, and the measured sideband suppression ratio (SSR) is −17.2 dBc. For both forward and backward phase shifting modes, measured results show that the proposed TVPS can achieve the phase resolution of 10-bits, RMS phase error of 0.2~0.5°, RMS gain error of less than 0.2 dB over the 12~18 GHz frequency band.