A Broadband 360° Distributed Vector-Summing Phase Shifter Achieving <1.99°/0.22-dB RMS Gain and Phase Error Over 8-to-110-GHz Bandwidth

This paper presents an ultra-broadband distributed vector-summing phase shifter (VS-PS) with fine resolution and full field of view over more than a decade of bandwidth. The design consists of optimally weighted distributed variable gain amplifiers (VGAs) and a three-stage polyphase quadrature hybrid network. An optimal weighting distribution is introduced, in which larger VGA cores (×4 and ×8) are divided into smaller units (×2) to improve gain and phase matching without increasing area. This approach enhances robustness against process variations and further extends the bandwidth. The impedance-invariant VGA maintains constant input and output impedances across all 1024 states, ensuring good interface matching (S11 and S22) up to beyond 100 GHz. Furthermore, the inherent load-invariant property of the broadband, multi-stage, transformer-based I/Q hybrid tolerates large load variations (10–80 Ω) while maintaining phase and amplitude mismatches within 3° and 1 dB, respectively, across an entire decade of bandwidth. Fabricated in 22-nm FDSOI CMOS, the prototype achieves phase shifting from 8 GHz to 110 GHz, with a fine phase resolution of 3°, low RMS gain and phase errors of <0.22 dB and <1.99°, and a power consumption of only 13 mW.