Level One Communications, Inc.

Paul James Hurst

Amit Gattani

David William Cline

Paulius Mosinskis

James W Everitt

Daniel L Ray

A method and apparatus for providing a self-sustaining precise voltage and current feedback biasing loop. The present invention provides a circuit for initially biasing the bandgap and master bias current generator at startup. The feedback biasing loop has loop dynamics that are chosen such that the gain of the positive feedback loop is less than one so that the loop will not oscillate under normal operation after power-up.

Method and apparatus for providing a self-sustaining precision voltage and current feedback biasing loop

A method and apparatus for matching common mode output voltage at a switched-capacitor to continuous-time interface. An active continuous time summation circuit is used at the output of the switched-capacitor stage to derive the common mode level that is at the output of the switched-capacitor stage. This derived signal is filtered to remove any noise component remaining in it, and is then used as the reference common mode signal in the continuous time stage. This forces the output common mode, and hence the input common mode of the unity gain amplifier stage, to track the common mode output of the switched-capacitor stage. This adaptive tracking eliminates the common mode interface error, which could be present and could vary from die to die (due to parasitic variations). This technique ensures proper tracking of the DC levels between the negative and the positive terminals of the unity gain amplifier, which is essential for low distortion operation of the amplifier.

Method and apparatus for matching common mode output voltage at a switched-capacitor to continuous-time interface

The analog adaptive equalizer provides convergence of an error signal by decoupling the error canceller, the automatic gain control and the filter to provide truly adaptive error minimization. The invention includes an automatic gain control (AGC) circuit for providing broadband amplification of an input signal to generate an AGC output signal, a filter for receiving the AGC output signal and providing high frequency signal conditioning to generate a filter output signal, an error detection circuit for generating an error signal representing the difference between the filter output signal and an expected output signal and a calculator for receiving the error signal and providing a gain correction signal to the automatic gain circuit to adjust the gain of the automatic gain circuit and a filter control signal to adjust the filter range of the filter, the gain correction signal and the filter control signal being used to cancel the error signal. The calculator further comprises a first in, first out buffer for providing a history of the expected output signal to the calculator.

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Vacaville, CA, United States of America

Paul James Hurst