about ADS

i found that the RF PA simulation with ADS isn't exact in fact. but the ADS is a very powerful tool to deal with it, so i have a question is that the soft can do what for us.
please give me some advice about it which may be your experience.thank you

u r rite...it's a very powerful tool to use.....try reading the manual.....it might helps....

Hi softstone. It possibly does more than you currently need it for. I wish you advance in knowledge and harnes the power of ADS.

It is an EDA application, capture, multiple kinds of simulation and export to gerber and other pcb formats. The difference with other EDA tools is that it is extremely rich in libraries. The best in ADS is that allows you in system level or circuit level design. It is mixed DSP/Analog package.

To be honest in commercial sector ADS is not that very much employed because of its cost not because it is not good.

Well all EDA software does is to use models to approximate an answer.
And when your are in or around the P-1db compression point, there
aren't any modles that can account for all of the the non-linearities.
Also for PA's I have found that I got better results when I used the
impedance of the device rather than a model.

ie. Port1 = 50Ohms & Port2 = Z11*(S11*) From data sheet .
This will be where you tune for the input matching network.

Port2 = 50Ohms & Port1 = Z22*(S22* From data sheet) .
This will be where you tune for the output matching network.

_______ ______
50-->[ Z11* ] --DUT--[ Z22* ]--->50
---------- --------

Cheers

PA is very complicated thing to model. Only thing you can do is load pull. The optimum load in the data sheet is quite useless since it was done on the manufacturer's substrate, heat sink, etc. you have to perform you own load pull and use that data in ADS. For example, 100-200 W PA, the optimum load is about 1-3 ohms, you see how sensitive it is.

it is powerful , reading manual and document will help you .