A Novel Fully Digital Feedforward Background Calibration Technique for Timing Mismatch in M-Channel Time-Interleaved ADCs

Abstract

This paper presents a novel digital background calibration technique for timing mismatches in time-interleaved analog-to-digital converters (TIADCs). We reconstruct and eliminate the timing mismatch based on the theory of timing-mismatch-induced spurious signals in the frequency domain. The proposed compensation algorithm utilizes the conjugate property between spurious signals to achieve low complexity. A coarse-fine correction architecture is adopted to eliminate higher-order time-skew errors. A novel feedforward estimation algorithm based on the correlation of adjacent channels is proposed to extract the time-skew errors. Our proposed calibration technique is suitable for an arbitrary number of channels. The simulation results demonstrate that the utilization of the proposed calibration technique yields significant improvements in both the signal-to-noise-and-distortion ratio (SNDR) and spurious-free dynamic range (SFDR). The SNDR and SFDR are improved from 55.82 dB and 56.64 dB to 79.92 dB and 105.98 dB, respectively.

An All-Digital Timing Mismatch Calibration Algorithm Based on Reference Channel for TIADC

“…Thereinto, the predominant error estimation methodologies entail the utilization of the cross-correlations among sub-channels [2,3,[7][8][9][10][11][12], or the introduction of a reference channel [13][14][15][16]. Based on the correlations among sub-channels, a complex computational matrix is commonly constructed.…”

“…Most compensation methods rely on either filtering techniques [18][19][20][21] or Taylor expansion [11,22,23]. Numerous structures of the commonly employed filter are subjects of the study, with a substantial portion of researchers directing their investigations toward fractional-delay filters and perfect-reconstruction filters.…”

“…Ref. [11] utilized a Taylor series expansion to approximate the error terms within the output signal. The calibration of the errors in the output signal was achieved through the consideration of the time misalignment errors and the derivatives of the input signal.…”