A 30–36 GHz Passive Hybrid Phase Shifter With a Transformer-Based High-Resolution Reflect-Type Phase Shifting Technique

Abstract

This brief presents a passive hybrid phase shifter consisted of a 5-bit switch-type phase shifter (STPS) and a 4-bit high resolution reflection-type phase shifter (RTPS). The STPS as the main body of the circuit utilizes the bridged T-type and high-pass/low-pass phase shifting cells. A novel high-resolution RTPS is proposed as a supplement of the STPS to improve the phase resolution and minimize the phase error. In the RTPS, a novel reflective load, which contains a transformer and a 4-bit digital-controlled switched capacitor array, is adopted. The transformer in the RTPS can weaken the variation of the reflection coefficient resulted by a large-capacitance switched capacitor array, which makes the control of the phase shifting more convenient and accurate at millimeter-wave (mm-wave) frequency. A proof-of-concept prototype was implemented in 55 nm CMOS technology. Measured results show that the root-mean-square (RMS) phase error of the proposed phase shifter in a step of 2.8° is 0.69 – 2.19° at 30 – 36 GHz, and less than 1.1° from 30 to 34 GHz. An average insertion loss (IL) of 12.6 – 14.6 dB is achieved. The core circuit occupies 0.24 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> without DC power consumption.