A 28 Ghz 8-Bit Calibration-Free Lo-Path Phase Shifter Using Transformer-Based Vector Summing Topology In 40 Nm Cmos

This paper presents an 8-bit calibration-free LO-path phase shifter (PS) for large scale 28 GHz phased-array transceiver. To overcome the nonlinearity of a vector-summing PS, two 8-bit digitally-controlled variable gain amplifier are utilized to generate high linearity amplitude modulation. Three transformers cooperating with a parallel resonator are developed to sum the I/Q signal as well as provide a fine isolation between I/Q path, thus provide a high linearity vector summation. Simulation results show that the PS achieves 360 degrees phase shift with 8-bit resolution and a RMS phase error of 0.51 degrees. The INL and DNL of phase-shifting is +0.66 degrees/-0.83 degrees and +0.22 degrees/-0.191 degrees respectively. Implemented in TSMC 40 nm LP process, the chip occupies an active area of 0.18 mm(2) and consumes 28.6 mW from 1.1 V supply voltage.