Other

National Semiconductor Corporation

Sushma Chandrasekaran

Hai T Nguyen

Vuong Le

Yu-Sheng Yang

An adaptive equalizer system and method uses an averaging algorithm to adjust equalization and amplitude for a data signal. Two sampled data points, spanning a sampling window, are obtained from the equalized signal. The data points are evaluated to determine when a signal condition persists long enough to require equalization adjustment, as well as evaluating persistent conditions in the amplitude of the received data signal. By monitoring persistent conditions in the equalized signal, the average signal received by the equalizer is compensated. The bit resolution of the equalizer control and the amplitude control can be selected for a desired resolution in a system. The incoming data signal is used to generate the requisite timing signals for sampling and control such that high frequency clock circuits and PLL techniques are unnecessary resulting in lower power consumption and reduced costs.

Apparatus and averaging method for equalizing signals

An input signal with an associated pulse width can be sampled using a sampling method that does not require a clock signal. The input signal is compared to a reference level signal to produce a comparator output signal. Strobe signals are generated from the input signal, where the strobe signals occur within a pulse width of the input signal. Sampled data points are generated in response to the comparator output signal and the strobe signals such that the sampled data points are within the pulse-width of the input signal. One of the strobe signals may be used to periodically reset the comparator. The sampling logic circuit may be constructed from common logic gates and memory circuits such as flip-flops. In one example application the sampling method is applied to an equalizer system. The equalizer system includes an equalizer circuit that produces an equalized signal. A data slicer circuit converts the equalized signal into a digital representation. The sampling method is applied to the output of the data slicer circuit to generate the sampled data points in the equalizer system. The sampled data points may be used in the equalizer system or any other system that requires samples of the input signal without the use of a clock signal. Since the sampling system uses the incoming data signal to generate the requisite timing signals for sampling, high frequency clock circuits and phase locked loop techniques are unnecessary resulting in lower power consumption and reduced costs.

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Milpitas, CA, United States of America

Sushma Chandrasekaran