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I'm not sure I understand
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How do you model offset? I model it by adding a DC source in series with the In+ or IN- gate. some value between 100uV and 10mV depending on the expected mismatch of the input pair. Model PSRR requires that you model the power supply, which a simple G/R model does not have, also the typical sources of non-ideal opamp performance that results in power supply variation transferring to the output signal neesd to be correctly modeled. simple things like the variations in current sources with power supply voltage, the correct model for this depends on weather you cascode the mirrors or not. Same thing with Cmrr? A differential G with perfect R load has infinite CMRR, modeling CMRR requires that you include errors that cause CMRR. in your model. This requires some knowledge of the Input pair type and the cascode bias levels. BTW most commercial device level spice models are very badly written. I mean VERY BADLY written. so they are unlikely to include these effects, heck Microchips opamp models usually don't even converge properly. The Microchip opamp spic models are very complex and attempt to model all types of errors and their Temp variations, but in the end these models cause convergence problems, so what is the point of a complex model that causes beginners convergence problems. Convergence can be hard for experienced spice users to solve, so it is the last thing that beginners need. So if you want to see some complex models go to Microchip and download some of their spice models. regards Robert --- In LTspice@..., Ganesan <dg1@...> wrote:
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