Background calibration of time-interleaved analog-to-digital converters

摘要

A robust and fast background calibration technique for correction of time-interleaved ADC offset, gain, bandwidth, and timing mismatches is proposed. The technique combines the use of a calibration signal and a reference ADC. The calibration signal enhances robustness and makes the technique independent of the input signal's statistics. The reference ADC speeds up convergence and enables the use of a small amplitude calibration signal that does not significantly reduce the input signal dynamic range. The calibration signal can be subtracted or filtered from the ADC output and is therefore invisible to the ADC user.

主权项

1. A time interleaved analog-to-digital converter (ADC) comprising:
a reference ADC coupled to receive an analog input signal combined with a calibration signal; a plurality of sub-ADCs coupled to receive the analog input signal combined with the calibration signal, the sub-ADCs configured to sample the analog input signal combined with the calibration signal using respective sample clock signals; and a plurality of calibration circuits coupled to the reference ADC and respective ones of the sub-ADCs, each of the calibration circuits being configured to determine respective timing errors between the reference ADC and the sub-ADCs and to provide respective timing mismatch estimates; and wherein each of the calibration circuits are further configured to adjust a gain of an associated sub-ADC to match a gain of the reference ADC.