A 60-GHz CMOS Broadband Heterodyne I/Q Up-Converter with Suppressed LOFeedthrough and Image Leakages

This study developed a 60-GHz CMOS heterodyne I/Q up-converter with local oscillator feedthrough (LOFT) suppression and I/Q calibration in 65-nm process. The compact onchip passive I/Q calibration circuits are proposed to suppress image leakage while requiring no additional power consumption. By using varactors and attenuators, the phase and gain difference of up to 20° and 1.5 dB can be calibrated in I/Q mixers, respectively. The proposed I/Q up-converter delivered a peak conversion gain of 4.2 dB across 55-6S.5 GHz for 3-dB bandwidth. With the proposed calibration, the measured LOFT suppression and IRR are 54 and 44 dB respectively, improved by 23.5 and 12 dB compared to without calibration, respectively.