S-Parameter can't be changed using S2P format ADS

[ramiruddin]

Hi,

I have designed power amplifier using data items model (S2P format) in ADS, but when I tried to change the bias voltage (Vdc), s-parameter simulation results did not change (S11, S22, S21). What's wrong with that??

 

[RealAEL]

There is nothing wrong in this case. This is exactly what they are supposed to do. S-parameters are not bias dependent in this way. An s-parameter file is measured data were the measurement are taken at a specific bias and that is the only condition for which the data is appropriate.

S-parameter data file models do not need to be biased at all to work. In fact you can simulate an s-parameter file within an otherwise passive circuit with resistors, capacitors, inductors etc. with no bias applied at all. The simulation results would be as if the circuit was biased at the levels specified by the s-parameter data and it will work just fine.

 

[ramiruddin]

When I tried to change component using microstrip line, it can work only at 2,5 Volt dc bias whereas on the datasheet bias value at 5 volt

 

[volker@muehlhaus]

It is what RealAEL said: S2P data is linear S-parameters, and only valid for that bias that was used in measurement. You really need to use the correct S2P for your bias condition. If you don't have that, you need to measure it, or get a model from component manufacturer or Modelithics (very complete component library, but not free!)