A iteration-free multi-channel mismatch estimation method for parallel time-interleaved system

Abstract

A time-interleaved (TI) architecture with slower sub-ADCs in parallel is a promising approach to avoid the conflict between sampling rate and quantization precision of single chip ADC. A major bottleneck in realizing a TI ADC is mismatch among the sub-ADCs, which may greatly degrade the receiver performance. An iteration-free method is proposed to simultaneously estimate time errors and gain errors. In our research, the frequency response vectors corresponding to a pair of frequencies are studied in terms of their rotational relationships. The method is based on the fact that the rotational matrix only depends on the time errors and the frequency spacing between the paired frequencies but is independent of gain errors. Upon combining the projection matrices corresponding to the paired frequencies, we directly obtain the time errors in terms of extracting the rotational matrix in a least squares framework. Moreover, the presented method is robust to residual offset errors and system noise. The effectiveness of the proposed approach is verified by simulated data.