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Deep dive: the instability of op-amps
A closer look at op-amp feedback loops and the stability criteria for circuits that use them.
Alas, the underlying theory is rather inaccessible to hobbyists; you’re either getting sucked into the discussion of zeroes and poles of complex-number transfer functions, or into obtuse jargon along the lines of this snippet from Analog Devices: Crucially, if the error signal is too large or too small, the negative feedback loop rectifies the problem in the blink of an eye, pulling Vout in the opposite direction until the balance is restored. At this point, we also have a preliminary explanation of one of the more counterintuitive properties of op-amps: that instability and some types of noise problems can get worse at lower signal amplification rates because of higher loop gain.
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