High Power Amplifier design? Need Help
I want to design an X band 12 Watt Power Amplifier with a chip HEMT.
I have designed low power Amplifiers befor. an I am familiar with packaged Transistor matching and biasing.
But what points are critical for High power Amps. (X band 12 Watt Power Amplifier)
Have any body any points , papers, good book or ...
They could not be similar to low power Amps? could they
especialiy with chips, what should I do?
Dear,
It's similar to low power design ,but depend on your design.In Low Power design
Amplifiers usually work in CLASS-A.When going to medium power and high power
They usually work in Class-AB & Class-C (Class-D,...). In low power you use
S-Parameters for matching design but in medium&high power you usually have only
Zin & Zout (or Zin & Zl) of the transistor (Optimum Input Impedance,Optimum Output Impedance ...)
and you must design matching circuit to convert 50 ohms to the Conjugate of Zl or Zin.
Finally Take a Look @:
http://www.eudyna.com/e/products_e/w...igh_powe2r.htm
They have internally matched power GaAs FETs (Matched to 50ohms).
Good Luck!
search for books by crips
they are very good and they are in the forum
good luck
I'm confused,as you said,the S parameter is used for lower power..but we know the S parameter is suitable for high frequency. so ,if one day ,you wanna design PA, work in high frequency with high power. which parameter could we choose?
For large signal design, s-parameters are no longer applicable. One must use large signa impedances. Z-parameters are often provided over a frequency range that the device is intended to operate. S-parameters are only suitable for linear excursions from the bias point, large signal implies non-linear excursions from the bias point or the non RF point. As mentioned, Cripps deals with this aspect quite well.
MoonShine
how can I find the crips books