A 26GHz to 34GHz Active Phase Shifter with Tunable Polyphase Filter for 5G Wireless Systems
Alok Sethi, Rehman Akbar, Mikko Hietanen, Timo Rahkonen, Aarno Pärssinen
Abstract
This paper presents a vector summing Active Phase Shifter (APS) for 5G and 6G wireless systems. The circuit is fabricated using 45nm CMOS SOI technology and exploits 10bit control to set the desired amplitude and phase. The design uses a high-precision tunable polyphase filter (PPF) whose center frequency can be tuned from 23GHz to 40GHz. By utilizing a tunable PPF and independent gain tuning of the quadrature signals along with a simple calibration, a square phase constellation is achieved over the full operating band, resulting in an easy phase control with a mean resolution of 0.5 degree and 7dB of amplitude control to facilitate amplitude tapering. The measured RMS phase and amplitude errors are as small as 0.6 degree and 0.08dB, respectively. Active area occupied is 0.19 sq. mm, allowing a high degree of integration in a phased array system.