Digital offset compensation of time-interleaved ADC using random chopper sampling

An ADC using several parallel cells suffers from offset differences between the cells, which causes non-harmonic distortion. A method for removing the offset in the digital domain is proposed. The method is based on a PRBS-controlled chopper at the ADC input, which transforms any input signal to noise. The randomization controls the batch size required for removing the offset by a mean value calculation. The measured results are SFDR=72 dB and SNDR=59.0 dB at 22 MS/s, an improvement of 19 dB and 10 dB respectively