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Linearization bias circuit for BJT amplifiers

  • US 6,426,677 B1
  • Filed: 09/14/2001
  • Issued: 07/30/2002
  • Est. Priority Date: 09/14/2001
  • Status: Expired due to Term
First Claim
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1. A linearization bias circuit for a bipolar junction transistor (BJT) amplifier including a base terminal that receives an input radio frequency (RF) signal, the linearization bias circuit comprising:

  • a reference circuit having a control terminal for coupling to the base terminal of the BJT amplifier and a reference terminal;

    a current device, coupled to the reference terminal of the reference circuit, that provides a constant reference current, wherein the constant reference current has a level that is based on a desired DC collector current of the BJT amplifier; and

    a transconductance amplifier, having an input coupled to the reference terminal of the reference circuit and an output coupled to the control terminal of the reference circuit, that asserts its output to maintain the constant reference current into the reference terminal of the reference circuit;

    wherein the reference circuit applies a predetermined relationship between DC and AC scale factors of collector current of the BJT amplifier so that the transconductance amplifier applies its output for controlling the base terminal of the BJT amplifier to modify the operating point of the BJT amplifier to substantially maintain constant transconductance.

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