Adaptive Digital Compensation of Analog Impairments in Frequency Interleaved ADC for Next-Generation High-Speed Communication Receivers

This paper presents an adaptive background compensation technique designed to address analog impairments in frequency-interleaved analog-to-digital converters. Frequency interleaving has been proposed as a solution to the bandwidth bottleneck of data converters in high-speed digital communication receivers, including those deployed in coherent optical transmission systems. The proposed technique combines an adaptive multiple-input multiple-output equalizer with the well-established backpropagation algorithm commonly utilized in machine learning. Unlike previous proposals, the new algorithm ( ${i}$ ) compensates the linear impairments in the analog front-end of the receiver (e.g., mismatches of track-and-hold and trans-impedance amplifier frequency responses, time skews, quadrature imbalance in electrical carriers, etc.), and (ii) maximizes the signal-to-noise ratio at the decision point of the receiver without requiring estimation of the channel parameters. The proposed background compensation scheme is thoroughly investigated in a dual-polarization coherent optical receiver with 16-QAM operating at ~200 GBd (i.e., ~1.6 Tbps). Numerical results show the excellent performance and high robustness of the new background compensation algorithm. These features, combined with its low implementation complexity, will pave the way for the deployment of commercial transceivers with bandwidths of 100 GHz and beyond.