Frequency Response Mismatches in 4-channel Time-Interleaved ADCs: Analysis, Blind Identification, and Correction

Abstract

This article proposes a novel adaptive architecture for blind identification and compensation of frequency response mismatches in 4-channel time-interleaved analog-to-digital-converters (TI-ADCs). Detailed frequency response mismatch modeling is first carried out elaborating in detail the interleaving mismatch spurs characteristics. Stemming from the established mirror-frequency crosstalk nature of the different mismatch spurs, the interleaving mismatch identification process is then carried out using complex second-order statistics based methods. The developed learning algorithm performs the mismatch identification and learns the mismatch compensation filter parameters in a blind manner for almost the full digital bandwidth of the 4 TI-ADC system. The proposed solution's efficiency and performance are verified and demonstrated using state-of-the-art RF-sampling TI-ADC hardware measurements with GHz range instantaneous bandwidth. In addition to this, the relationship between a four-channel TI-ADC and an I/Q sampling 2-channel TI-ADC is explored and an interesting link between the two is established in this work.