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Automatic gain control system for a direct conversion receiver

  • US 5,095,533 A
  • Filed: 03/23/1990
  • Issued: 03/10/1992
  • Est. Priority Date: 03/23/1990
  • Status: Expired due to Fees
First Claim
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1. An automatic gain control system for use in a direct conversion receiver having a plurality of baseband signal channels for carrying separate baseband signal components, comprising:

  • a polyphase rectifier for generating a rectified signal reflective of the voltage levels on all of said channels;

    control means coupled to said rectifier for generating a digital word control signal corresponding to the voltage level of said rectified signal and suitable for use in controlling a multiplying DAC;

    a plurality of multiplying DACs which are coupled to said control means and one of which is installed on each of said channels for uniformly attenuating said baseband signal components to varying degrees in response to said digital word control signal; and

    clock generator means for supplying clock signals at different frequencies to said control means in order to select the speed of operation of said gain control system and provide for rapidly increasing attenuation (fast attack) and slowly decreasing attenuation (slow release) when the receiver is processing amplitude modulated signals and provide for both very rapidly increasing and very rapidly decreasing attenuation when the receiver is processing angle modulated signals.

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