ADS Amplifier Model Help

Hi all.
i use model of NPT1004 of Nitronex. When i make loadpull i can't reach the maximum power the transistor is capable according to datasheet. When i increase the input power the simulation shows error of non-convergence. I play with some advanced parameters at HB simulation and it improve the performance but i still can't reach the maximum output power and simulation still crashes at higher input power. I saw the such performance while using the Infineon LDMOS ADS models. Freescale's work good without problem. Do i make something wrong? Or may be the model is not accurate enough?
Thanks a lot

Simulation just gets your design close. If you are within a few dB of P,max then I'd consider the model good enough and move on to design your circuit. Once you build that circuit in the lab, you can verify/validate the ADS model. If you have concerns over the ADS model validity, you might build a very simple, narrowband circuit to test your part. That way you could see how close the simulation meets reality. Remember, real parts will have variation against the nominal spec sheet values, so keep that in mind while you test.

Don't trust the models too much...
They are only models and just consist of mathematical equations.
Real world will give you the best result

I am something like 5dB less... it means 10W instead 45W. I don't think is good enough. For a while i don't have an evaluation board so i can't check model as i do usual before design starts.
Anyway i already saw how amplifier of 80.000S nearly screwed up because the bad model. And sometimes for some complicated designs you do need to rely on model

Hi,

Bias the amplifier in ADS and then put a harmonic balance port at the input and change the 50 ohm impedance to r1+j*x1 and at the output change the ports 50 ohm impedance to r2+j*x2. Define these r1,r2,x1,x2 as variables. optimize the impedance for the output power you want. You can also use AWR for simulation and i think AWR models are better.

Also nitronex has bad temperature characteristics, when you build you circuit make sure that it is cooled down as well as possible.

As a final recommendation Cree's transistors are better:)

Cheers..

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