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Digitally controlled programmable attenuator

  • US 5,757,220 A
  • Filed: 12/23/1996
  • Issued: 05/26/1998
  • Est. Priority Date: 12/23/1996
  • Status: Expired due to Term
First Claim
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1. A digitally controlled programmable attenuator, comprising:

  • a multi-tap resistive ladder network that attenuates an analog voltage signal to establish a plurality of voltage signals at its taps having different attenuation levels;

    a plurality of voltage-to-voltage buffers that are connected between the respective taps and a common output, said buffers having respective digital inputs for receiving a digital signal that turns on one of said buffers so that the voltage signal at its tap is switched through to the common output while the other buffers are held off, each said buffer presenting a substantially constant impedance, whether on or off, at its tap so that the voltage signals switched through said buffers to said common output are approximately phase matched; and

    a fixed gain stage that amplifies the voltage signal at the common output by a fixed gain level to set the attenuator'"'"'s overall gain range.

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