Signal with AC and DC how to amplify only AC?

  • #1
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Main Question or Discussion Point

Hi, I have a sine-wave that has an AC component (that's very small -- mV range) and a DC offset (few volts). Can someone point me in the right direction as far as amplifying only the AC component?

Also, does anyone know an alternative to PSpice Student... I get max'd out at 64 nodes, so I can't any simulation if I exceed that value. Thanks.
 

Answers and Replies

  • #2
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filter out the dc component. Take the AC/DC go through a high pass filter (either RC,LC,op-amp depending on cutoff). These will remove the Dc offset.
Then a rail-rail op-amp to amplify the AC signal. Use a low noise amplifier like a JFET.
 
  • #3
berkeman
Mentor
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Yeah, just AC couple the signal into your opamp circuit through a capacitor. Choose the capacitor value to put the HPF pole (the C in combination with the equivalent input R of the opamp circuit) a couple octaves below the AC component's frequency.
 

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