Hi!
I'm in the midst of designing my first audio power amplifier and I ran into a problem with the input stage.
I'd like to utilise a long tail pair similar to the one attached (I made a few changes to make matters simpler) and it looks like it works fine except for a huge positive DC shift at the output and a noticeable amount of distortion of the signal's negative half.
I've never used a long tail pair before so I don't really know what goes on in the circuit (at least not yet) but I noticed that the offset becomes more positive and distortion worsens as I raise gain.
So questions are the following:
I'm in the midst of designing my first audio power amplifier and I ran into a problem with the input stage.
I'd like to utilise a long tail pair similar to the one attached (I made a few changes to make matters simpler) and it looks like it works fine except for a huge positive DC shift at the output and a noticeable amount of distortion of the signal's negative half.
I've never used a long tail pair before so I don't really know what goes on in the circuit (at least not yet) but I noticed that the offset becomes more positive and distortion worsens as I raise gain.
So questions are the following:
- Why is there a DC offset and distortion in the first place?
- Are these two phenomenons related?
- How could these issues be eliminated?
Attachments
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