A Real-Time Calibration Method for Time-Interleaved Analog-to-Digital Convert System in Wideband Digital Radar

• Published in: IEEE transactions on instrumentation and measurement Vol. 73; pp. 1 - 17
• Main Authors: Peng, Xiangyu, Zheng, Zixiang, Zhang, Yue, Wang, Wei
• Format: Journal Article
• Language: English
• Published: New York IEEE 2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Analog to digital converters; Broadband; Broadband channel mismatches; Broadband communication; Calibration; Channel estimation; Circuits; Error compensation; Estimation; Field programmable gate arrays; linear frequency-modulated (LFM) signal; Noise levels; optimized perfect reconstruction (OPR) structure; Radar; Radar echoes; Real time; real-time calibration; Real-time systems; Reference signals; Signal processing; Time-frequency analysis; time-interleaved analog-to-digital converter; wideband digital radar (WDR)
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2023.3328077

The employment of time-interleaved analog-to-digital converter (TIADC) technology in wideband digital radar (WDR) receivers enables the adaptation to the ever-increasing bandwidth demands. Nevertheless, the performance of TIADC is significantly affected by channel mismatch errors. This article presents a real-time calibration method for TIADCs utilized in WDR. The calibration process involves two steps: broadband mismatches estimation and compensation, respectively. First, a novel approach is proposed to estimate broadband mismatches by utilizing the transmitted signal-linear frequency-modulated (LFM) signal-as a reference signal. Compared with conventional techniques, this new approach offers lower computational complexity and more streamlined hardware circuitry. Second, in the mismatches compensation step, an optimized perfect reconstruction (OPR) structure is implemented to decrease computational resource usage and increase processing speed. Finally, the compensation of mismatches is implemented in the field-programmable gate array (FPGA). The speed of error compensation is equal to the data generation rate, enabling the TIADC system to transmit the corrected radar echo data to the signal processing unit in real time. The experiment results show that the spurious-free dynamic range (SFDR) is improved by more than 15 dB and the signal-to-noise and distortion ratio (SNDR) is improved by more than 10 dB after real-time calibration.