A CMOS 77-GHz Receiver Front-End for Automotive Radar

This paper presents the design of a receiver (Rx) front-end for automotive radar application operating at 76-77 GHz. The Rx employs a double conversion architecture, which consists of a five-stage low-noise amplifier (LNA), a sub-harmonic mixer (SHM), and a double-balanced passive mixer (PSM). By adopting this architecture, millimeter-wave frequency synthesizer design can be relaxed. In the LNA layout, the output of each stage is positioned close to the input of the follow stage, thus creating a LC resonance load. As a result, complex interstage matching networks is simplified. The SHM driven by a 38-GHz local oscillator (LO) is adopted to avoid push/pull effect and power consumption of the voltage-controlled oscillator. A PSM is utilized for the second conversion since it consumes no dc current and has low flickering noise. To connect the singled-ended LNA and SHM, a 77-GHz balun is designed; and for driving the SHM, two 38-GHz baluns and an in-phase/quadrature coupler to provide quadrature 38-GHz LO are designed. The proposed Rx is implemented in a 65-nm CMOS technology and measurement results show 16-dB voltage gain and 13-dB calculated noise figure while dissipating 23.5 mA from a black 1.2-V supply.