Parallel mode adaptive transversal equalizer for high-speed digital

Abstract

In a parallel-mode adaptive transversal equalizer, P- and Q-channel data streams from A/D converters (1, 5) are respectively passed through the tapped-delay lines of trasversal filters (2, 6), on the one hand, and are one-symbol delayed, on the other, by delay circuits (3, 7, 66, 67) to produce (N-1) successively delayed P- and Q-channel data streams, which are respectively passed through the tapped delay lines of transversal filters (4; 63, 8; 64). In each trasversal filter, symbols appearing at successive taps of the tapped-delay line are sampled and held for a duration of N symbols to produce first and second groups of stored symbols, the stored symbols of the first group being multiplied by first tap weights and summed, producing N first equalized outputs for each channel. The stored symbols of the second are multiplied by second tap weights and summed, producing N second equalized outputs for each channel. The first equalized outputs of each channel are respectively combined by adders (10-14, 68, 69) with the second equalized outputs of the otehr channel and multiplexed (14, 15) into P- and Q-channel outputs. Correlations are detected by correlators (16-19, 70, 72) between data and error components of each of the P- and Q-channel outputs to control the first variable tap weights of associated tapped-delay lines, and correlations are detected by correlators (20-23, 71, 73) between data components of one of the P- and Q-channel outputs and error components of the other channel output to control the second variable tap weights of associated tapped-delay lines.