Intel Corporation

Level One Communications, Inc.

Susumu Hara

Hassan Ihs

An analog bias current optimization circuitry in a transceiver of a data communication system is capable of controlling the amount of a bias current of each of analog circuits. The analog bias current optimization circuitry generates a signal pattern which is sent to the analog circuits, such as TX-D/A converter, driver, RX-A/D converter, etc., and evaluates the signal quality of the analog circuits. Based on the evaluated signal quality, a bias current to each of the analog circuits is adjusted. A margin may be added to the bias current to ensure the signal quality in case there is a change in power supply voltage and/or temperature. One method of evaluating the signal quality of the analog circuits is to evaluate the residual echo of the output of an echo canceller (EC). Another method is to evaluate a signal error in a decision feedback equalizer (DFE). A further method is to evaluate a harmonic distortion at the output of a filter.

Method and apparatus for analog bias current optimization

A method and circuitry for implementing a built-in self test (BIST) for determining the frequency characteristics of filter circuits in mixed-signal integrated circuits (ICs). The method comprises inserting a Circuit Under Test (CUT) into a feedback loop that looks like a sigma delta modulation loop and adjust the feedback loop so that it oscillates at the cut-off frequency of the filter. The frequency of oscillation can then easily be measured using either on on-chip counter or digital automated testing equipment. The feedback loop preferably comprises a comparator, a phase-delay component, such as a delay-line, and a one-bit DAC (digital-to-analog converter), wherein the comparator is connected to the output of the CUT, and the output of the one-bit DAC is connected to the input of the CUT. The phase delay of the feedback loop can be tuned through adjustment of the delay-line (e.g., an n-length shift register) until an oscillation frequency is obtained. In the case of low-pass filters circuits, the tuned frequency of oscillation corresponds to the cut-off frequency of the CUT.

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Gold River, CA, United States of America

Susumu Hara