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Direct current offset canceling circuit of trans-impedance amplifier and automatic gain control trans-impedance amplifier thereof

  • US 20060290432A1
  • Filed: 09/23/2005
  • Published: 12/28/2006
  • Est. Priority Date: 06/22/2005
  • Status: Active Grant
First Claim
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1. A direct current (DC) offset canceling circuit of trans-impedance amplifier used for filtering a DC component of an input current, comprising:

  • a trans-impedance amplifier having an input end and an output end, wherein the input end is used for receiving the input current, and converting the input current into a first voltage signal to be output by the output end, said trans-impedance amplifier comprising;

    a plurality of inverters connected in series, wherein a sample node is defined between the inverters and at the input and output ends of the trans-impedance amplifier respectively; and

    a resistor having one end connected to the input end, and the other end connected to the output end;

    a DC detector for retrieving and comparing the signals at any sample node, thereby generating a trigger signal;

    a DC eliminator connected to the input end of the trans-impedance amplifier, for providing a path to the DC component of the input current in response to the triggering by the trigger signal, to eliminate the DC component;

    a reference voltage unit for outputting a reference voltage value; and

    a voltage output amplifier for comparing the reference voltage and the first voltage signals, to amplify the output of a second voltage signal.

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