An ultra-wideband low-power ADPLL chirp synthesizer with adaptive loop bandwidth in 65nm CMOS

Abstract

The paper presents an ultra-wideband, low-power frequency synthesizer for Ku-band FMCW radars. This ADPLL-based frequency synthesizer generates chirps with configurable rate from 0.4 to 3.2GHz/ms, up to 2GHz bandwidth in triangle or sawtooth mode. Adaptive loop bandwidth is adopted to reduce variations of the loop tracking characteristic during ramping under different chirp rate, by which, a low frequency RMS error of ~179kHz is achieved for the chirp rate below 2GHz/ms. Fabricated in a 65nm CMOS, the synthesizer generates a wideband chirp from 13.8GHz to 15.8GHz, and consumes 36.3mW, featuring state of the art performance.