Abstract: A high-linearity down mixer with outstanding robust temperature tolerance for V-band applications is proposed in this paper. The mixer’s temperature robustness has been greatly enhanced by employing a negative temperature-compensation circuit (NTC) and a positive temperature-compensation circuit (PTC) in the transconductance (g_m) stage and intermediate frequency (IF) output buffer, respectively. Benefiting from the active balun with enhanced g_m and emitter negative feedback technique, the linearity of the mixer has been significantly improved. For verification, a double-balanced V-band mixer is designed and implemented in a 130 nm SiGe BiCMOS process. Measured over the local oscillator (LO) bandwidth from 57 GHz to 63 GHz, the mixer demonstrates a peak conversion gain (CG) of −0.5 dB, a minimal noise figure (NF) of 11.5 dB, and an input 1 dB compression point (IP_{1 dB}) of 4.8 dBm under an LO power of −3 dBm. Furthermore, the measurements of CG, NF, and IP_{1 dB} exhibit commendable consistency within the temperature range of −55 °C to 85 °C, with fluctuations of less than 0.8 dB, 1 dB, and 1.2 dBm, respectively. From 57 GHz to 63 GHz, the measured LO-to-radio frequency (RF) isolation is better than 46 dB, the measured return loss at the RF port is >29 dB, and at the LO port it exceeds 12 dB. With a 2.5 V supply voltage, the mixer power consumption is 15.75 mW, 18.5 mW, and 21 mW at temperatures of −55 °C, 25 °C, and 85 °C, respectively. Moreover, the mixer chip occupies a total silicon area of 0.56 mm² including all testing pads.

Key words: V-band; Down-conversion mixer; SiGe BiCMOS; Temperature compensation; High-linearity; Active balun

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