A 76-84 GHz CMOS × Subharmonic Mixer with Internal Phase Correction

Abstract

A CMOS 4\times subharmonic mixer (SHM) with an internal phase error correction mechanism operating at mm-wave frequencies is proposed in this paper. The SHM operates with a 81-GHz RF input signal and a 20-GHz local oscillator (LO) signal to produce a 1-GHz output. The single ended input is converted into octet-phase, through an active input balun, an active polyphase filter, and certain phase adders. A phase calibration technique is employed, to compensate the phase deviations due to the circuit mismatches, offering a ±5° phase adjustment between the generated phase shifts. By this technique, a close to optimal performance can be obtained, especially in terms of conversion gain and LO-IF isolation, which can be improved by 1.5 to 7.5 dB and by 5 to 17 dB, respectively. Fabricated in a 65-nm CMOS low-power technology, the prototype exhibits a conversion gain of -8 dB (without using an IF amplifier), a 1 dB compression point ( \text{P}-{\mathrm {1dB}} ) of -10 dBm, a third-order intercept point (IIP3) of 1 dBm, and a noise figure of 15 dB. The power consumption is 213 mW, and port-to-port isolation is >70 dB. The achieved performance compares well with the state of the art at these high frequencies despite the use of a slower CMOS process. © 2004-2012 IEEE.