Joint background calibration of gain and timing mismatch errors with low hardware cost for time‐interleaved ADCs

Abstract

A joint background calibration scheme is proposed for the gain and timing mismatch errors in time-interleaved analogue-to-digital converts (TI ADCs). Mixed-signal calibration is adopted for timing mismatch without using correlators or multi-tap digital filters, while the gain mismatch is estimated and calibrated all digitally based on the moving average of the derivative for each channel's output. Therefore, the influence of offset mismatch on the estimation accuracy of the gain error can be eliminated completely. To reduce hardware cost as much as possible, most of the arithmetic blocks are reused for gain and timing mismatch estimation. Behavioural simulation with a 12 bit, 2 GSPS two-channel TI ADC and measurement results from a commercial 12 bit 3.6 GSPS two-channel TI ADC show that the proposed joint calibration scheme can effectively correct the gain and timing mismatch errors.