A 2-channel TIADC frequency response mismatch calibration method based on frequency domain adaptive filtering

To achieve high sample rates, the system can utilize multiple analog-to-digital converters (ADCs) employing the time-interleaved analog-to-digital conversion (TIADC) technique. In TIADC, the calibration of mismatch error has received much attention. In this brief, a calibration method for frequency response mismatch (FRM) of two-channel time-interleaved analogue-to-digital converters (TIADCs) is proposed. The channel frequency response is approximated by means of polynomial fitting and the coefficients of the polynomials are estimated using a frequency domain adaptive filtering (FDAF) algorithm. The desire signal of adaptive filter can be exploit with slight oversampling. Utilizing the acquired coefficients, it is possible to compensate for the FRM of the parallel acquisition system. The proposed algorithm provides more accurate gradient estimation and faster rate of convergence compared to the traditional algorithm. We construct a dual-channel TIADC system with a sampling rate of 12.5 GSPS. The simulation result also shows the efficiency of the proposed calibration method. After applying the proposed calibration algorithm, SNR of the system is improved about 22 dB.