I get a 49.8 Hz 2.5 Vpk-pk sine signal. I want to amplify this signal and drive a 22 Ω resistor. Do you have a chance to provide an example of amplifier circuit design? As a result of this upgrade, THD should be less than 5%.

  • 3
    \$\begingroup\$ Amplify...by what factor? \$\endgroup\$
    – vir
    Commented Jul 1 at 7:34
  • \$\begingroup\$ factor value 10 \$\endgroup\$
    – Ozan AKYOL
    Commented Jul 1 at 8:04
  • 2
    \$\begingroup\$ Why don‘t you propose an amplifier design and we help you . \$\endgroup\$ Commented Jul 1 at 11:00
  • \$\begingroup\$ @OzanAKYOL When someone asks for a detail that is missing in the question, don't answer by commenting. Instead, EDIT your question to add the missing detail, then flag the comment asking for clarification as "no longer needed". \$\endgroup\$ Commented Jul 1 at 15:11
  • \$\begingroup\$ A 1:10 transformer? \$\endgroup\$
    – winny
    Commented Jul 1 at 15:17

1 Answer 1


You have a 2.5 Vpk-pk signal, that's 1.25 Vpk. Amplify that by 10 (20 dB) and you've got 12.5 Vpk or 8.84 Vrms. Into 22Ω that's 3.55 Wrms. Peak current will be 568 mA.

So you need an amplifier that will output 12.5 Vpk, at 568 mA. Typical opamps aren't going to give you this much current, you'll either need to boost the output of one or use something like a discrete amp, probably class AB. You're supply rails are going to need to give you enough head room, so probably +/- 15 V minimum, +/- 18 V would be better.

A discrete amp will give you the power you need, but they're not as easy to get an exact gain with as an opamp. If you need it to be exactly a gain of 10 you could use an opamp with a class AB emitter follower buffer and take the feedback from after the buffer.


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