Circuit for a controllable amplifier

  • US 5,389,893 A
  • Filed: 10/19/1993
  • Issued: 02/14/1995
  • Est. Priority Date: 04/25/1991
  • Status: Expired due to Term
First Claim
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1. A circuit for a controllable amplifier, provided with a differential amplifier for an input voltage, said differential amplifier containing a first transistor and a second transistor, the emitters of said transistors being connected by resistors, and wherein:

  • said emitters of said first and second transistors are connected by a series circuit of at least three resistors;

    wherein a respective component whose resistance can be controlled is branched off between said resistors, each of said components being connected to a respective current source;

    wherein the current from said current sources can be altered in dependence on the input voltage, andwherein, in the event that the middle resistor of the resistors in the series circuit is divided into two individual resistors, no component having a controllable resistance is branched off from the junction of these two resistors.

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