Analysis and design of K-band low-phase-noise differential DCOs implemented in 22 nm FD-SOI for 76–81 GHz automotive radars

Abstract

This paper presents two K-band low-phase-noise digitally controlled oscillators (DCOs) with a frequency tuning range (FTR) of more than 20% for 76–81 GHz automotive radars. The proposed triple-bank DCO (T-DCO) relies on the medium-tuning and fine-tuning banks to cover the linear chirp band, thus facing the issues of complex frequency calibration and frequency overlap of more than 15% like conventional DCOs. To address these issues, an original dual-bank DCO (D-DCO) is proposed, which solely relies on the large fine-tuning bank to achieve a fine frequency resolution of 2 MHz and a fine-tuning range of 1.94 GHz by employing a customized MOM capacitor of 973 aF. Moreover, both T-DCO and D-DCO are implemented in a 22 nm FD-SOI process, achieving the best-in-class phase noise lower than −110 dBc/Hz over the entire frequency range at 1 MHz frequency offset, while consuming 24 mW from a 1.2 V supply voltage.