Low-complexity digital correction of 4-channel time-interleaved ADC frequency response mismatch using adaptive I/Q signal processing

This paper proposes a novel fully blind frequency response mismatches correction architecture for a four-channel time interleaved ADC (TI-ADC) using digital signal processing. By generating appropriate complex valued signals from the real valued TI-ADC output, a mapping of the TI-ADC problem into a mirror frequency interference problem is obtained, which allows using in-phase/quadrature (I/Q) mismatch correction techniques, e.g., circularity, for the frequency response mismatch identification. Compared to the existing methods in the literature, the proposed method allows for blind frequency response mismatch identification throughout the whole digital bandwidth and has substantially lower computational complexity while maintaining similar correction performance, hence making it suitable for an on-chip implementation. The compensation architecture is implemented, demonstrated and tested using real RF-sampling four-channel TI-ADC hardware data, achieving a multitone spur reduction below 80 dBFS.