Analog-baseband circuit with large dynamic range and fine-grained gain control for 77-GHz millimeter-wave radar systems

doi:10.3969/j.issn.1000-5641.2026.02.013

Abstract

Abstract:

In this study, an analog-baseband (ABB) circuit for 77 GHz automotive radar transceivers, which features a large dynamic range and fine-grained gain control, is proposed and implemented. To accommodate various detection ranges from short (15 m) to long distance (250 m), the circuit employs a Butterworth filter supporting a signal bandwidth of 400 kHz to 20 MHz with a continuously tunable gain of 10 to 57 dB. A precision gain control strategy is proposed, which enables 2.5 dB/step gain adjustments to precisely maintain the output amplitude within 460–740 mV. A feedback-based direct current (DC) offset cancellation loop effectively suppresses residual DC offsets. The hybrid digital-analog feedback automatic gain control ensures a settling time of less than 160 μs during rapid signal amplitude variations. At the output stage, a highly linear source-follower structure is implemented to minimize signal distortion while enhancing the ABB’s driving capability. Measured results indicate that under a 2.5 V power supply, the analog baseband affords a wide range of automatic gain tuning from 10 to 57 dB across the full operating bandwidth (400 kHz–20 MHz). At the maximum gain, the circuit exhibits noise figures of 42.4 and 33.1 dB at 400 kHz and 20 MHz, respectively.

Key words: 77-GHz band, automotive millimeter-wave radar, fine-grained gain control, analog-baseband (ABB)

CLC Number:

TN432

Zihao REN, Cong ZHANG, Yang YANG, Chunqi SHI. Analog-baseband circuit with large dynamic range and fine-grained gain control for 77-GHz millimeter-wave radar systems[J]. J* E* C* N* U* N* S*, 2026, 2026(2): 139-150.

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Table 1

References 13

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参考文献	工艺尺寸/nm	增益调谐范围/dB	中频带宽/MHz	噪声系数/dB	增益步长/dB	稳定时间/μs
[4]	65	0~42	0.1~5	18.9@5 MHz	/	/
[5]	65	10~52	0.15~15	15.3@15 MHz	6	100
[10]	22	3~45	800~1000	/	/	200
[11]	65	0~53.5	0.7~10	35.5@10 MHz	0.5	800
[12]	65	18.2~70.6	0.2~10	/	5.8	/
[13]	40	24~50	0.175~10/15	18.26@5 MHz	2	/
本文	55	10~57	0.4~20	42.4@0.4MHz 33.1@20MHz	2.5	≤160

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