Digital background skew calibration for time-interleaved shared-front-end SHA-less pipelined ADCs

This paper proposed a structure of SHA-less pipelined time-interleaved ADC (TI-ADC) with shared front-end sub-ADC. SHA-less techniques are employed to pursue power efficiency. However, in contrast with traditional TI-ADC with skew error among channel ADCs, TI-ADC with SHA-less pipelined channel ADCs also introduces aperture error between T/H and sub-AD at the front-end stage. By sharing front-end sub-AD, the structure and algorithm of skew error calibration is greatly simplified. In-situ and correlation-based skew error calibration are both applied in the structure. Simulation of a 14-bit 4-channel TI-ADC shows that with digital skew calibration SFDR is improved from 38.29dB to 86.64dB when the input frequency is at 230MHz.