A fully-integrated Doppler-assisted FMCW radar for indoor localization and vital sign sensing

doi:10.3969/j.issn.1000-5641.2026.02.012

Abstract

Abstract:

This paper presents a Doppler-assisted frequency-modulated continuous-wave (FMCW) radar that combines the precise range resolution capability of FMCW with the high sensitivity of Doppler radar, enabling versatile performance for indoor applications. A comprehensive analysis of low-frequency noise contributions from key receiver blocks, including the low-noise amplifier (LNA), mixer, local oscillator (LO) buffer, and analog baseband (ABB) circuits, is conducted. An “RF+LO+BB” joint noise figure (NF) improvement method is proposed to effectively suppress the low-frequency noise. To reduce frequency modulation (FM) error in charge-pump-based fractional-N phase-locked loop (PLL), a nested-PLL architecture with a co-optimized loop parameter selection method is employed, resulting in significantly improved chirp linearity. Fabricated in a 55 nm CMOS technology, the proposed Doppler-assisted FMCW radar achieves NFs of 32 dB and 12 dB at 10 Hz and 1 kHz, respectively, and a chirp linearity of 0.0039% over a 3.52 GHz chirp bandwidth (BW), resulting in a maximum detection range of 19.41 m and a range resolution of 4.7 cm. The radar occupies a die area of 12.7 mm² and consumes 594 mW in FMCW mode and 432 mW in Doppler mode under a 3.3 V supply.

Key words: frequency-modulated continuous wave, Doppler, radar, complementary metal-oxide semiconductor

CLC Number:

TN958.2

Yuqin ZHANG, Zitong ZHANG, Runxi ZHANG. A fully-integrated Doppler-assisted FMCW radar for indoor localization and vital sign sensing[J]. J* E* C* N* U* N* S*, 2026, 2026(2): 128-138.

Figures/Tables 9

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Table 1

References 28

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数据来源	工艺	模式	中心频率/GHz	发射功率/dBm	噪声系数/dB	相位噪声 @1 MHz/ (dBc/Hz)	RMS扫频线性度	芯片面积/mm²	功耗/mW
本文	55 nm CMOS	Doppler- assisted FMCW	24~27 (FMCW) 24(Doppler)	6.0	32 @ 10 Hz IF 12 @ 1 kHz IF	–89.69	0.0039% @ 12.5 MHz/μs 0.018% @ 40 MHz/μs	12.7	594 (FMCW) 432 (Doppler)
TMTT 2024 ^[22]	65 nm CMOS	FMCW	24	10.6	45 @ 10 kHz IF 13.5 @ 400 kHz IF	–80.00	0.11% @ 2.5 MHz/μs 0.355% @ 5 MHz/μs	8.4	407 (FMCW)
TMTT 2020 ^[4]	65 nm CMOS	Doppler	100	4.0				1.8	262 (Doppler)
JSSC 2020 ^[20]	65 nm CMOS	FMCW	79	13.4	15.3 @ 600 kHz IF	–93.43	0.003% @ 13.3 MHz/μs 0.11% @ 133 MHz/μs	7.3	921 (FMCW)
ISSCC 2020 ^[10]	65 nm CMOS	FMCW	77	11.8~14.5	12.2~20.2 @ 0.1-20 MHz IF	–90.00	0.008% @ 18 MHz/μs 0.32% @ 312.5 MHz/μs	33.6	3150 (FMCW)

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