A 60-90 GHz Mixer-First Receiver With Adaptive Temperature-Compensation Technique

This letter demonstrates a high-linearity mixer-first receiver (RX) covering a frequency range of 60-90 GHz for radar applications. Its core mixer is realized by a passive double-balanced ring structure to achieve both high linearity and low local-oscillator (LO) leakage. To improve robustness of millimeter-wave (mm-wave) radar systems to temperature variation, two temperature-compensation bias circuits are proposed for the mixer and amplifiers in the RX, which are implemented by devices with different temperature coefficients. Measured characteristics show that it achieves a peak conversion gain (CG) of 18.5 dB at 76 GHz, a 3-dB gain bandwidth of >30 GHz, and LO-to-RF isolation of >35 dB across 60-90 GHz. The RX's tested 1-dB input compression point ( \text {IP}_{\mathrm{ 1\,dB}} ) and noise figure (NF) are −4 dBm and 7.7 dB at 78.5 GHz. Thanks to the proposed temperature-compensation techniques, the RX supports a wide temperature range, and tested CG, \text {IP}_{\mathrm{ 1\,dB}} , and NF variations are less than 1.6, 1.0, and 2.9 dB across from −20 °C to +100 °C, respectively.