Design of high-linearity 75–90 GHz CMOS down-conversion mixer for automotive radar

Abstract

This paper presents a 75–90 GHz down-conversion mixer applied in automotive radar, which is characterized with high linearity, low local oscillator (LO) drive as well as high conversion gain (CG) using TSMC 65-nm CMOS general-purpose technology. The good linearity and isolation of mixer are required for automotive radar to cover short-middle-far range detection. The mixer includes an enhanced double-balanced Gilbert-cell core with series peaking transmission line and source degeneration technique for improving linearity and CG, two on-chip baluns and intermediate frequency (IF) buffer for IF test. Besides, to make the design more accurate and efficient, the modeling and design of millimeter-wave (mm-wave) passive devices are introduced. The mixer consumes 12 mW under 1.5 V. The input 1 dB compression point (P1dB) is 2.5 dBm as well as IIP3 of 13.2 dBm at 80 GHz. High performances are achieved with the CG of 5 dB at 76 GHz with LO power of 0 dBm for frequencies of 75–90 GHz which covers the application of automotive radar frequency band (76–81 GHz) and LO-RF isolation of 33–37 dB for frequencies of 60–90 GHz. The area of the mixer is 0.14 mm2, with PADs included.