A 6-Bit E-band Vector-Sum Phase Shifter With Transformer-Based Hybrid in 65nm CMOS

In this paper, a 6-Bit E-band vector-sum phase shifter based on a 65 nm CMOS process is proposed. A transformer- based fully differential hybrid is designed to generate high-precision orthogonal signals, which presents a compact layout and effectively widens the operating bandwidth. Besides, a low phase invariance technique is applied to variable gain amplifiers (VGAs). The measurement results exhibit that the proposed circuit achieves a 360° phase shifting range with 5.625° step in the wideband from 69 GHz to 81 GHz. The root-mean-square (RMS) phase error is only 1.17° at the center frequency (f0), and the RMS amplitude error is less than 1.2dB. Thanks to the proposed quadrature generator, the core area of the phase shifter is 500×240 μm².