OPA541 improved with OPA452

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2nd Edition -- in respect of Bob's IP I will let you fill in the blanks:

That's not a composite amp, though. It's an LM3886 with an input buffer and a DC servo.

A composite amp uses the loop gain of a precision opamp to perform error correction on a less precise power amp. It's an old trick, actually. You can find it in many opamp texts, including Franco.

When designing composite amps (or possibly amps of any kind) beware that the simulation models don't always match reality when the output approaches the supply rails. That's certainly the case for the LM3886 model and the biggest contributor to the complexity of the compensation.

Tom
 
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