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@ericfont

ericfont/circuit-20251114-1210.svg

Created November 14, 2025 17:22
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feedback oscillates when total loop phase is 0 or multiple of 2pi (i.e. Berkhausen)
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ericfont commented Nov 14, 2025

image image

0 phase occurs exactly at 6.85kHz. The actual oscillation is a little lower than that because inverters of course add some minor delay too.

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ericfont commented Nov 14, 2025

That output RC lowpass filter with cutoff freq 1Mhz seems to be equivalent to having 1 MHz GBWP inside the opamp:

image

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ericfont commented Nov 15, 2025

sim

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