High-Efficiency Calibration Methodology of Interchannel Mismatches in TIADCs Based on Digital Orthogonal Local Oscillation Signal

Abstract

The article proposes a novel foreground integrated calibration method based on the digital orthogonal local oscillation signal to address interchannel mismatches in time-interleaved analog-to-digital converters (TIADCs). In contrast to existing approaches, this methodology eliminates the requirement for analog auxiliary circuit configuration while obviating the necessity of employing extensive matrix operations and inverse Fourier transform computations. The employment of the phase difference elimination technique, in conjunction with the approximate calculation of the inverse tangent function, has been demonstrated to yield enhanced calibration performance and optimized design resource utilization. The register transfer level (RTL) simulation results demonstrate that for a 12-bit four-channel TIADC model, the amplitude of the mismatch-induced spurs is suppressed below −82 dB following calibration, and signal-to-noise and distortion ratio (SNDR) and spurious-free dynamic range (SFDR) reach 72.6- and 83.7-dB frequency of sampling (FS), respectively. The experimental results of the field-programmable gate array (FPGA)-based measurement demonstrate that, under the sinusoidal input frequencies of 498 and 1448 MHz, the SNDR increased by 27.4 and 24.5 dB, respectively, both prior to and following calibration. Furthermore, the SFDR increased by 35.7 and 30.7 dB, respectively.