Title: Gain control circuit capable of reducing change in gain due to variation of ambient temperature
Application Number: 200610075122 Application Date: 2006.04.24
Publication Number: 1862955 Publication Date: 2006.11.15
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: H03G3/20,H03G3/30
Applicant(s) Name: ALPS Electric Co., Ltd. Address:
Inventor(s) Name: Asano Shoichi
Attorney & Agent: liu jian
Abstract:
     A gain control circuit capable of keeping a constant gain without being affected by ambient temperature includes a variable resistor element connected to a power supply terminal, a control unit for controlling the resistance value of the variable resistor element on the basis of a gain control voltage, an amplifying transistor that is supplied with a power supply voltage through the variable resistor element, a current detecting resistor that is interposed between the variable resistor element and a collector of the amplifying transistor, and a voltage detecting unit that detects a drop dropped by the current detecting resistor. The dropped voltage detected by the voltage detecting unit is fed back to the control unit to control the resistance value of the variable resistor element such that a current flowing through the current detecting resistor does not vary.
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