use transistor as voltage controlled attentuator/amplifier with square wave

Discussion in 'Analog & Mixed-Signal Design' started by Green Bean, Jul 12, 2018.

  1. Green Bean

    Thread Starter Member

    Mar 31, 2017
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    Is there anything wrong with using a transistor to control the amplitude of a square wave with voltage like in this circuit?
    sim: http://tinyurl.com/y7xxzlzj
    pic:
    Screenshot_2018-07-12-15-03-23_kindlephoto-233740848.png

    The square wave signal is just switching the transistor on and off, passing the voltage through, that's how it works. That being said, the circuit would only work for a square wave obviously. The sine wave is just modulating the amplitude, a dc voltage could also be used of course. Is there any reason this wouldn't work in real life?
     
  2. dl324

    AAC Fanatic!

    Mar 30, 2015
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    Other than making no sense?
     
  3. crutschow

    Expert

    Mar 14, 2008
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    If you want to chop a sinewave with a square-wave, that should work.
    Any analog CMOS switch will do the same.
     
    Green Bean likes this.
  4. Green Bean

    Thread Starter Member

    Mar 31, 2017
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    It works in the sim (??)
     
  5. Green Bean

    Thread Starter Member

    Mar 31, 2017
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    1
    I guess that's one way of describing it but the point is that the sine wave is modulating the amplitude of the square wave.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    What's the difference? :confused:
     
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