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P-Channel Fet Amp?

  1. May 17, 2007 #1
    I came across a schematic of a buffer amplifier utilizing a p-channel fet as input. It is from a sweep oscillator generating a ramp voltage by charging C3 and C4 with a constant current, (current source is not shown, Q2 just acts as a switch or buffer). Now as the voltage rises linearly across C3 or C4 the gate of the p-channel fet Q3 picks it up and the amplifies it from -5 to 5 volts in conjunction with Q1.

    So what I'm trying to accomplish is to derive an expression of the output voltage (-5 to 5) as a function of the input voltage at the gate Q3. P channel fets always confused me.
    Last edited: Dec 19, 2010
  2. jcsd
  3. May 20, 2007 #2
    Never mind I solved this, a good exercise though.
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