A Low Computation Adaptive Blind Mismatch Correction for Time-Interleaved ADCs

Abstract

We introduce a computationally very efficient technique for adaptive blind correction of M-channel time-interleaved analog-todigital converters (TIADC). Under wide-sense stationary (WSS) and bandlimited input assumption, gain and timing errors are estimated in the digital domain by detecting shift-dependence of TIADC output autocorrelation. Input signal integrity is preserved since there is no analog input pre-processing. Gain mismatch is digitally corrected, but sampling time mismatches are compensated in the analog domain by adjusting individual clock timing offsets. This mixed-domain technique takes advantage of each domain to dramatically reduce computational requirement on the digital side. As a by-product, convergence is guaranteed under mild conditions with arbitrary number of channels.Experimental demonstration is performed by a proof-of-concept, M=4 400-MSPS real-time setup. After 300 iterations, mismatch spurs are suppressed by more than 40-dB, down to -80dB below the signal at -171MHz. This is the first proposal and demonstration of lowcomputation blind technique with guaranteed convergence.

Mixed-Domain Adaptive Blind Correction of High-Resolution Time-Interleaved ADCs

“…In accordance with the above discussion, the authors previously reported a new mixed-domain blind method with analog tuning of sampling clocks [26]. This paper presents a full-fledged discussion with theory and new experimental results.…”

“…Single-tone test result across the first two Nyquist zones (N = 4,096). The sign of the correlation derivative and convergence parameters is also shown (see (26), (27)). The input anti-aliasing filter in Fig.…”

“…Currently known mismatch correction techniques can be categorized into training (foreground) [2], [6] and blind (background) methods [7]- [26]. Training methods are suitable for high-resolution application in general, since they are capable of correcting general linear mismatches [6], but at the cost of suspension of data acquisition during each calibration.…”

Mismatch calibration methods for high-speed time-interleaved ADCs

“…The mixed calibration technique presented in [18] does not require an additional ADC but assumes that the signal is WSS to adaptively estimate the timing skews through a correlationbased algorithm.…”