Just checking, I'm doing some experimenting of small signal RF design in LTspice.
Electronic – Are the stock transistor models in LTspice accurate at RF
ltspicemodelRFtransistors
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Best Answer
I use microcap (which uses standard transistor spice files) and there's plenty of times I'm simulating in the low hundreds of MHz for analogue and digital signals. If I don't pick the correct transistor it doesn't work (and neither would it in the real world).
I've pretty much designed radio front ends at 400MHz and got reasonable results when implementing the circuits - sure, component values need tweaking and the odd decoupler adding but you have to remember that spice simulators are not really a guarantee of performance but they are reasonable guarantor of functionality.
If something appears to functionally work in spice then you will likely get it to function in real life but, at high frequencies the PCB layout/grounding is something that you need to know a lot about. Spice doesn't help you with this.