Voltage-Controlled Amplifier


Posted on Jun 21, 2012

The CA3080 can be used as a gain controlling device. The input signal is attenuated by R1/R2 so that a 20-mVpp


Voltage-Controlled Amplifier
Click here to download the full size of the above Circuit.

signal is applied to the input terminals. If this voltage is much larger, significant distortion will occur at the output. In fact, this distortion is put to good use in the triangle-to-sine wave converter. The gain of the circuit is controlled by the magnitude of the current IABC. This current flows into the CA3080 at pin 5, which is held at one diode voltage drop above the - VCc rail· The gain of the CA3080 is " "linearly" proportional to the magnitude of the IABC current over a range of 0.1 to 1 mA. Thus, by controlling IABC, you can control the signal level at the output. The output is a current output, which has to be "dumped" into a resistive load (R5) to produce a voltage output. The output impedance at IC1 pin 6 is 10 kfi (R5), but this is "unloaded" by the voltage follower (IC2) to produce a low output impedance. The circuit around IC3 is a precision voltage-to-current converter and this can be used to generate IABC. When Vm (control) is positive, it linearly controls the gain of the circuit. When it is negative, IABC is zero and so the gain is zero.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    15 Watt Amplifier
    Auto light Controller and Visitor Counter
    Mp pulse width control
    Low-power-rs-232c-driver
    Use of N-channel power MOSFET on BQ78PL114
    rf detector electronic project circuit design using 2n2222 transistors
    microcontroller Why this transistor logic as switch is not working
    Implementing Infrared Object Detection
    gps receiver for kenwood tm d710e
    Circuit for a test circuit with the PIC16F84A
    Arduino AVR High-Voltage Serial Programmer



    Top