Half-rate dfe with duplicate path for high data-rate operation

Abstract

Methods and circuits are presented for providing equalization, including decision feedback equalization (DFE), to high data-rate signals. Half-rate delay-chain circuitry produces delayed samples of an input signal using two or more delay-chain circuits operating at a fraction of the input signal data-rate. Two delay-chain circuits operating at one-half the input signal data-rate may be used. More generally, n delay-chain circuits operating at 1/n the input signal data-rate may be used. Multiplexer circuitry combines the outputs of the delay-chain circuits to produce an output signal including samples of the input signal at the input signal data-rate. Duplicate path DFE circuitry includes two paths used to provide DFE equalization while reducing the load of the DFE circuitry on the circuitry that precedes it. A first path produces delayed samples of a DFE signal, while a second path produces the DFE output signal from the delayed samples.