An Optimizing Method for FMCW Chirp Linearity Based on Continuous Frequency Step Analysis

This paper presents a method for optimizing chirp linearity in frequency-modulated continuous wave (FMCW) signal sources, utilizing continuous frequency step analysis. The study delves into the connection between the phase-locked loop (PLL) loop bandwidth and the chirp slope. Additionally, it examines how variations in frequency step granularity impact the root mean square (RMS) FM error across three distinct radar operational modes: long-range, medium-range, and short-range. Guided by the proposed optimization model, an FMCW signal source has been designed using a 55 nm CMOS process. This design occupies an area of 1.6 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and consuming 178.4 mW of power. The prototype demonstrates a chirp bandwidth of 5.4 GHz and achieves RMS FM errors of 152.7,167, and 201.3 kHz with the chirp slopes of 13.2,22, and 44 MHz/μs, respectively.