I have built a BJT amplifier and I have a function generator connected to the input of my circuit. I have also connected both channels of an oscilloscope to the input and output of my circuit. I need to find the maximum input I can provide to my circuit. I have done this by increasing the output voltage on the function generator until I just see clipping on my output waveform and then I read off the value of the input voltage i.e. from the function generator. I have also see where persons have increases the output of the function generator until they see clipping and then they find the swing and divide it by the max gain of the circuit to determine the max input value. Which approach is the correct approach.

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    \$\begingroup\$ Is visible clipping your metric? or is 1% distortion (which you will not be able to see, but only a couple mVPP across the Base-Emitter junction will cause 1% distortion), your goal? \$\endgroup\$ Nov 25, 2019 at 11:33
  • \$\begingroup\$ Visible clipping \$\endgroup\$ Nov 25, 2019 at 11:42
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    \$\begingroup\$ Both approaches are correct as long as the amplifier isn't clipping. When the amp is clipping the gain is reduced so the gain must be determined when it is not clipping. \$\endgroup\$ Nov 25, 2019 at 11:59
  • \$\begingroup\$ What I did was increase the input level to the circuit until clipping and just roll of the input i.e. decrease it slowly until there is no clipping and then used the corresponding input. Would this be sufficient to say there isn't clipping. \$\endgroup\$ Nov 25, 2019 at 12:03
  • \$\begingroup\$ Yes that would be sufficient. There is only so much you can see on a scope so the accuracy of your measurement is limited anyway. But that's OK! In a professional environment different methods using more expensive equipment would be used. Then an audio analyzer or a spectrum analyzer would be used. \$\endgroup\$ Nov 25, 2019 at 14:38


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