266 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 63, NO. 1, JANUARY 2015 A Reconfigurable 50-Mb/s-1 Gb/s Pulse Compression Radar Signal Processor With Offset Calibration in 90-nm CMOS Jun Li, Student Member, IEEE, Mehmet Parlak, Student Member, IEEE, Hirohito Mukai, Member, IEEE, Michiaki Matsuo, Member, IEEE, and James F. Buckwalter, Member, IEEE Abstract—This paper presents a reconfigurable mixed-signal- processing circuit for high-speed pulse compression radar (PCR). Mixed-signal design techniques incorporate calibration and adap- tation to improve the performance of a PCR receiver. Adaptive bandwidth PCR is an important feature for maximizing the dynamic range of a low-power radar system. The baseband signal processor includes a variable gain amplifier, 4-bit digital-to-analog converter, high-speed analog correlator, passive integrator, a 4-bit flash analog-to-digital converter, and a multi-range delay-locked loop. This proposed system is fabricated in 90-nm CMOS and can be configured to work from 50 Mb/s to 1 Gb/s with 2/3/5/7-bit Barker codes. The proposed calibration techniques improve the sidelobe reduction to 15.6 dB at 1 Gb/s. The total power con- sumption is 42 mW at the peak rate of 1 Gb/s for 15-cm range resolution. Index Terms—Analog correlation, Barker code, dc-offset cali- bration, delay-locked loop (DLL), flash analog-to-digital converter (ADC), pulse compression radar (PCR). I. INTRODUCTION A DVANCES in silicon technology have made possible new sensor applications at millimeter-wave bands that require low power and low cost. As a result, silicon inte- grated beamforming architectures and phased arrays have been demonstrated for millimeter-wave automotive radar system [1], high-definition content streaming [2], and satellite systems [3]. This work focuses on millimeter-wave radar circuitry such as short-range radars for parking assistance or side-crash preven- tion, which needs wide bandwidth for high-range resolution. Other applications include range detection to maintain safe driving distance between vehicles in heavy traffic [4]. Manuscript received October 25, 2014; accepted November 15, 2014. Date of publication December 18, 2014; date of current version December 31, 2014. J. Li and J. F. Buckwalter are with the Department of Electrical and Computer Engineering, University of California at San Diego (UCSD), La Jolla, CA 92093 USA (e-mail: j6li@ucsd.edu; buckwalter@ece.ucsd.edu). M. Parlak was with Department of Electrical and Computer Engineering, University of California at San Diego (UCSD), La Jolla, CA 92093 USA. He is now with the Broadcom Corporation, Irvine, CA 92617 USA (e-mail: mparlak@ucsd.edu). H. Mukai is with the Panasonic Corporation, Tokyo 153-8687, Japan. M. Matsuo is with the Panasonic Corporation, Yokohama 153-8687, Japan. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TMTT.2014.2375177 Fig. 1. Proposed millimeter-wave and analog-processing-based PCR system. An intelligent adaptive cruise control (ACC) system is also possible with long-range radars to perform a real-time response by means of the braking system or other protective mechanism. With proper control algorithms, anticollision systems would greatly reduce traffic casualties. In general, two main radar systems have been proposed [5]: frequency modulated continuous wave (FMCW) radar [1], [6], [7] and pulse compression radar (PCR) [8]–[12]. FMCW radar measures the range by using linear frequency modu- lation, which results in a low-cost architecture, but requires two isolated antennas for high receiver sensitivity. PCR uses digital signal modulation and time-division duplexing of the RF between transmit and receive. In this paper, a high dynamic-range baseband signal pro- cessor is presented for PCR. As shown in Fig. 1, the direction and range of a target is determined through a combination of the spatial selectivity of a millimeter-wave beamformer and analog signal processing. In earlier work, a low-power analog signal correlator and delay-locked loop (DLL) was demonstrated for broadband signals [13]. However, the analog correlator cannot 0018-9480 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.