Stability of Power Amplifier

Hello all,

This is the first time I design a PA, and I want to check if its stable or not using ADS. Its a Class J, 10W gan amplifier,

Thanks

Class-J actually is just a very well optimized Class-AB for input/output matching and harmonics terminations, to get best linearity and efficiency.
For a linear Class-A PA can be applied the low signal S parameters (and K factor) to get stability information.
Probably the same thing could be applied for Class-AB or Class-J in your case, at least to get some stability information.

Thanks. I used a series resistor in gate to stabilize but have some problem at low frequency. What to do at this point and if I use a parallel capacitor with the resistor, Whats the role of it ?

A gate resistor is a good option to improve stability (check the gain change), but a cap may affect the matching vs frequency, and needs some optimization for your specific case.

Hello maroc
which transistor are you using? Even i am going for a PA thats class AB.......for x band.......output is 10W.......using ads.........can you show your ads results!