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Digitally controlled gain stage having an analogue control input

  • US 7,323,922 B1
  • Filed: 07/20/2004
  • Issued: 01/29/2008
  • Est. Priority Date: 07/20/2004
  • Status: Active Grant
First Claim
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1. Gain control circuitry for controlling the gain of a signal path, the gain control circuitry comprising:

  • comparator circuitry configured to receive a first analogue input and provide a first digital output in response to receiving the first analogue input having a value greater than an upper threshold value or less than a lower threshold value;

    a bi-directional counter configured to provide a digital gain control signal to a digitally controlled gain device and configured to change the value of the digital gain control signal in response to receiving the first digital output from the comparator circuitry;

    a digital-to-analogue converter configured to convert the digital gain control signal to a first analogue output signal;

    a subtractor configured to receive the first analogue output signal from the digital-to-analogue converter and an analogue gain control signal and to provide a second analogue output signal representative of the difference between the value of the first analogue output signal from the digital-to-analogue converter and the analogue gain control signal, the second analogue output signal being provided as the first analogue input to the comparator circuitry.

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