A W-Band 0.18-dB RMS Gain and 0.97° Phase Error Active Phase Shifter in 28-nm CMOS

A W-band active phase shifter (PS) using two Gilbert-cell variable gain amplifiers (VGAs) with double-controlled digital-to-analog converters (DACs) and a high-order differential transformer-based quadrature generator (QG) is proposed, which is fabricated in 28-nm CMOS process. By controlling the two tail currents independently of the Gilbert cell, the proposed VGA can achieve a high resolution and a low-phase variation. The proposed high-order QG generates I/Q signals with low area cost and low insertion loss (IL) in a large frequency range of 86–96 GHz. The minimal root-mean-square (rms) gain error and phase error are measured to be 0.18 dB and 0.97° for 64 states of the 6-bit 360° phase. It shows −6 dB maximum gain with a variation below 1.1 dB including buffers and on-chip balun losses with 54 mW dc power consumption.