Bandwidth-efficient calibration method for nonlinear errors in M-channel time-interleaved ADCs

A Calibration Method for Nonlinear Mismatches in M-Channel Time-Interleaved Analog-to-Digital Converters Based on Hadamard Sequences

“…The only requirement is a slight oversampling, which is anyhow commonly adopted in most practical TIADC systems. Compared with the approach proposed in [25], our method consumes much less hardware resources by replacing the sinusoidal modulation sequences with the binary Hadamard sequences.…”

“…By finding the discrete-time Fourier transform (DTFT) of y[n], the output in the frequency domain is written as [25]:…”

“…Most of them aim at the compensation methods for the linear mismatches, including gain, time-skew and frequency response mismatches [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. By comparison, relatively few papers have been published to address the nonlinear mismatches problem, which stems from the imperfection of front-end circuits, as well as the differential and integral nonlinearities of sub-ADCs [21][22][23][24][25][26][27][28].…”

“…A digital compensation method that relies on the foreground estimated nonlinearities is presented in [26], where a sinusoidal signal is employed as the training signal during the estimation procedure. A blind calibration method is proposed in [27,28] for 2-TIADCs and extended in [25] for M-TIADCs.…”

“…The bandwidth efficient (BWE) method proposed in [25] is able to calibrate the nonlinear mismatches in M-TIADCs, as long as the mismatch-induced error signals are present in the input-free band, which is generated by a slight oversampling. However, there are two major drawbacks of the BWE method.…”