Digital Foreground Calibration for 20-Bit Pipelined SAR ADC Based on Hybrid Whale Optimization and Genetic Algorithm

This paper presents a digital foreground calibration scheme for high-resolution pipelined successive-approximation-register (SAR) analog-to-digital converters (ADCs) to address capacitor mismatch and inter-stage gain error. A 20-bit behavioral model is established, and the search for optimal weight coefficients is formulated as the minimization of the negative signal-to-noise-and-distortion ratio (SNDR). The whale optimization algorithm (WOA) performs global and local search, while a lightweight genetic algorithm (GA) module activates upon stagnation to maintain diversity and escape local optima. A comparator metastability-detection technique extracts and compensates first-stage offset. Simulation results show that the proposed hybrid calibration algorithm improves the ADC’s SNDR from 68.34  dB to 103.89 dB, yielding an enhancement of approximately 35  dB, with repeated trials confirming robust stability. The offset calibration technique extends the tolerable comparator offset range to roughly ±11 mV.