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If the ringing changes as you say it does, then something nonlinear is You how the circuit would respond IF it were 100% linear.

With megavolts from your AC signal sources and it will dutifully show That may be going on, and to any nonlinearities in your circuit (asideįrom the above steps of finding their small-signal equivalents at theĭC operating point).

AC analysis is totally blind to any large-signal effects Operating point, then effectively substituting these linearĮquivalents for the nonlinear devices. Small-signal equivalent impedance of all nonlinear elements at the AC analysis first linearizes the circuit, by figuring out the Should I try multi-tone or is that also fraught with assumptions?ĪC analysis is blind to signal amplitudes.Īn. Sounds cool and yet undependable and I wondered if anyone had any insight into this possible inability to get my AC sim to show the Bode Plot given a certain signal input strength. I've found a google search hit that indicated that one can use a multitone input signal in the transient sim and then use FFT to see the envelope of the response. So I'm left wondering if I'm in a world of Large Signal vs. AC response is maybe > 10X the frequency of the ringing. AC simulation correlates to, but I definitely don't see -180 degrees phase anywhere near the ringing frequencies as seen in the transient sim. I'm actually not sure which signal strength the. AC simulation should give some indication of this, right? Nope. The ring frequency also seems to increase slightly with input signal strength. In the transient simulation I see a step response where increased signal causes increased underdamped response and prolonged ringing. Ok, so I do this and the response is confusing. AC response in order to diagnose stability from a Bode standpoint. Now, I'm comfortable with looking at the time domain and frequency domain response while tuning a circuit, but I am being asked to look at the. STEP PARAM statement and have identified varying responses based on the input signal strength. I have run the transient response of my circuit with a. I am attempting to use LTSpice for a design at work but have run into a snag.