Digitally Assisted 28 GHz Active Phase Shifter With 0.1 dB/0.5° RMS Magnitude/Phase Errors and Enhanced Linearity.

This brief presents a new digitally assisted vector-summing phase shifter (DA-VSPS) featuring high accuracy and enhanced linearity. It begins by highlighting the RF performance degradation of traditional DA-VSPSs operating at millimeter-wave frequencies due to the large number of unit-cells and the significant underlying parasitics. Then, a new DA-VSPS topology is proposed to mitigate this source of performance degradation using analog variable-gain amplifiers with digitally assisted current sources. A study of the accuracy and linearity of the proposed DA-VSPS is conducted to inform the choice of the optimal parameters (number of unit-cells and load impedance) that maximize the RF performance while minimizing the implementation complexity. A proof-of-concept prototype was implemented in 45 nm silicon-on-insulator CMOS technology. The measurement results demonstrated a 1-dB RF bandwidth from 27 to 33 GHz, root-mean-square magnitude and phase errors of 0.1 dB and 0.5° to 0.6°, respectively, while covering 360° of phase shifts at 5° resolution. Furthermore, the measured group delay and input 1dB compression point are maintained within ± 4 ps and >2.2 dBm, respectively, at any phase shift settings. [ABSTRACT FROM AUTHOR]