I am studying the application of error amplifiers, and I have not encountered non-inverting error amplifiers so far.In practice, the goal is, of course, negative feedback. However, when driving an optocoupler with an error amplifier, two configurations are possible.
In one case, the LED's cathode is driven. However, due to the Fast Lane effect, this requires a voltage that is isolated from \$V_{out}\$. In this setup, if \$V_{out}\$ increases, the LED current increases, and \$V_e\$ decreases (negative feedback).
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If we want to drive the LED's anode instead, the following happens:If \$V_{out}\$ increases, the LED current decreases, and \$V_e\$ increases (positive feedback!).Thus, the optocoupler would need to be used in a common-collector configuration, or the error amplifier would have to be used in a non-inverting configuration.
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I tried to sketch a non-inverting Type II error amplifier, whose transfer function matches that of an inverting Type II error amplifier (two poles, one zero).
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My question is whether this compensation technique could be practically used?
EDIT:
I analyzed the circuit, and it indeed seems to function as a Type II amplifier. Assuming the error amplifier is ideal, there is a zero, a pole at the origin, and another pole. This is a classic Type II configuration.
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By the way, it can also be converted to a Type III by adding an extra zero in the input voltage divider.
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Should I test this in practice?
