Low-power Low-complexity Design of Frequency Modulated Continuous Wave Radar Transceivers

Abstract

A 3.75-4.25GHz frequency modulated continuous wave (FMCW) radar transceiver, employing intermediate-frequency (IF) delay rather than RF beat frequency to represent distance, is implemented in 65nm CMOS for applications in ultra-wideband (UWB) band. To overcome the trade-off between wide bandwidth and high ranging resolution in the conventional FMCW radars, a dual-BPF regenerative FM demodulator and a time-to-digital converter (TDC) are utilized to achieve low power, low complexity, and fine ranging resolution. In the transmitter, a slew rate controlled relaxation oscillator and a 3-stage RF voltage-controlled oscillator (VCO) are hired to perform frequency modulation with significant power savings. In addition, a successive approximation register (SAR) logic based automatic frequency calibration (AFC) loop is placed in the transmitter to calibrate the frequencies of the oscillators for process, voltage and temperature (PVT) robustness consideration. The proposed transceiver with 3.3mW power consumption and −110dBm sensitivity, features sub-cm ranging capability, better than the conventional designs with tens of centimeters resolution.