simple help with LTspice model

[cncjerry]

If I wanted to lower the slew rate of a transistor, basically limit it frequency response, what parameter would I modify, assuming this is so simple?

I'm trying to figure out what is going on where my spice model doesn't match the live circuit.  Only thing I can figure is that the MC3346 NPN array is somehow not performing as expected.

Thanks

Jerry

[Wimberleytech]

CJE and CJC, but you are just poking around in the dark fiddling with these.  You should try to find the models for that device.

[cncjerry]

Wimberleytech, thanks.  I have the model for the RCA part, CA3046 and as expected the bandwidth is much higher than the live circuit (I don't see the rise time increase through the amp).  I wanted to play with as you suggest CJE and CJC to see if by increasing them I can in effect better duplicate the live circuit.  Adding 50pf just about anywhere will cause the problem I am seeing in the actual circuit.

I find it hard to believe the NPN array failed as well as it having such a high junction capacitance from the start.  I mean it is always possible, as I've only ever seen these used in low frequency applications but then again, that would only be about 4 or 5 data points.

Thanks again,

Jerry

[Wimberleytech]

Adding 50pf just about anywhere will cause the problem I am seeing in the actual circuit.

Yup, that seems a bit large.  What is the circuit you are building/simulating?

I suggest that you simulate a single transistor and test for f_t and see if it matches with the datasheet.