A 21 to 30-GHz Merged Digital-Controlled High Resolution Phase Shifter-Programmable Gain Amplifier with Orthogonal Phase and Gain Control for 5-G Phase Array Application

This paper presents a 21 to 30-GHz merged passive vector sum phase shifter (PS) and programmable gain amplifier (PGA) with sub-degree phase resolution for 5-G phased array application. In PS, a transformer-based full-differential high-order resonant coupler functions as a quadrature generator (QG) with a novel layout strategy to achieve broad bandwidth, low loss, and accurate quadrature phase within only one inductor-footprint. Compared to the conventional transformer-based fourth order resonant coupler, the proposed resonant coupler with higher order features much wider quadrature bandwidth. Two phase invariant 6-bit binary-weighted arrays of vector modulators scale the quadrature signals to achieve the desired high resolution vector phase interpolation. In PGA, a phase invariant and dB-linear gain is achieved by adopting a "fractional-bit-based" PGA design. The chip prototype is fabricated in a 65-nm CMOS process, this implementation achieves 43% fractional BW_-3dB (20 to 31-GHz). The phase control operates with 0.8° steps while maintaining a minimum RMS phase error of 0.42°, demonstrating the best phase accuracy when compared to state-of-the-art mm-wave PSs.