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ad4897 spice model prooblem

MarkFredette
on Jun 28, 2012

I downloaded the ad4897 spice model to use in a simulattion of a 2nd order 3.6 MHz LPF.

I use LtSpice.

The model would not run until I commented out the BF value for the npn model. (BF= -45455.5454545455).

Then, the model ran, but gave strange looking results. I tried the same circuit with both the ad8040 and the ad8062 OpAmps and the simulation looked fine.

I have heard that the model will not run on IntuSoft, but for another reason. I think that problem was in the line 'HVnoise    12    7    Vvnoise    1', and that it should be 'HVnoise    9    7    Vvnoise    1'. Making that change in LtSpice makes no difference in the output.

Tried changing the BF to +45455 and got better results (see below). Apparently LtSpice does not like BF < 0. InttuSoft does not seem to mind. Not sure about other spice progrqams.

Still would like to know about the

'HVnoise 12 7 Vvnoise 1',

problem with IntuSoft.