A 170 MHz to 330 MHz Wideband 90 nm CMOS RC–CR Phase Shifter with Integrated On-Line Amplitude Locked Loop Calibration for Hartley Image Rejection Transceiver

Abstract

A 160 MHz bandwidth 90° active RC–CR phase shifter with integrated on-line amplitude locked loop (ALL) calibration targeted to 802.11ac 5 GHz wireless local area network (WLAN) applications is presented in this paper. The quadrature phase shifter is a key component for transceivers employing the Hartley image rejection architecture. The passive RC–CR phase shifter generates the required two quadrature outputs with an accurate 90° phase shift over the required bandwidth but lack the required accuracy in amplitude matching. A 90 nm CMOS microelectronic implementation of an RC–CR phase shifter is proposed with active resistors that are adjusted by an integrated on-line ALL calibration system to maintain matching amplitudes of the quadrature outputs over the required bandwidth. The on-line ALL calibration system employs peak detectors, comparators, digital logic control, and charge pump to incrementally adjust the active resistors while converging to matched amplitudes similar to the operation of phase-locked loop with a phase-frequency detector and charge pump. The resulting 90 nm implementation supports − 40db to − 70db image rejection ratios (IMMRs) over the IF 170 MHz to 330 MHz bandwidth. The 90 nm CMOS implementation is fully functional considering process variations based on 200 Monte Carlo simulations.