A Simple Histogram-Based Capacitor Mismatch Calibration in SAR ADCs

This brief presents a simple capacitor mismatch calibration in SAR ADCs, which is in foreground and on chip. Capacitor errors are extracted based on output histogram under a triangular input signal generated on chip and compensated by tuning capacitors with a calibration DAC. A novel one-by-one strategy can simplify the extraction by isolating the individual contribution of each capacitor error. The proposed calibration needs no computation and is validated with a 10-bit 100MS/s SAR ADC. Size of the ADC core including calibration system is only 90μm×97μm. Measurement results show effectiveness of the proposed calibration.