LMS-FIR based digital background calibration for the four-channel time-interleaved ADC

Abstract

The backstage calibration method based on LMS-FIR and interpolation filter for a four-channel time-interleaved analog-to-digital converter (TI-ADC) is presented in this paper. The analysis is made for the mismatch between sub-channels of multi-channel TI-ADC, such as offset mismatch, gain mismatch, and sampling jitter. Using the LMS calibration algorithm can reduce the performance loss caused by the mismatch errors. The proposed four-channel TI-ADC is designed in a 90nm CMOS process. The pre-corrected input is 12.55MHz and sampling frequency is 200MHz with mismatch errors, SNDR is 44.0dB, the effective number of bit(ENOB) is 7.0 bit, and SFDR is 53.4dBFS. After correction, the spurious performance is significantly reduced and the overall noise reduction is decreased, the SNDR is 65.6dB and ENOB is 10.6 bit. The calibration effect is obvious with ENOB inproved by 3.6 bit and the spurious performance decreased by 30.7 dBFS.