akhilpaulv
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It seems that you got confused with the optimal source/load impedance. The datasheet says 52.6+ j22.8 as the optimal load impedance. But you put a capacitor in series, this will end up with load impedance of 52.6- j22.8. Probably the same for the optimal source impedance.
i put it for conjugate matching.
The problem may come from the s-parameter of your amplifier. Have you double checked that the amplifier s-parameter matches with the datasheet? As you can see, different IQD affect the input/output impedance significantly.View attachment 151573View attachment 151574View attachment 151575
as per your comment i did the simulation. Still the stability parameter is not greater than one in 900 MHz. The input reflection coefficient is not less than -10 dB. Can you please tell me where i am wrong ?
View attachment 151585
i wrongly entered the impedance value in the simulator. Now i matched both in put and output, still the amplifier is not stable in that region. Can you help me to stabilize the transistor?
Just remind another thing. The S-parameter is obtained by assuming ideal load/source terminations. For your case, you need to optimize both input and output impedance. When you put an impedance matching network at output, the input impedance is NOT the same as S11 of the amplifier any more since your load impedance is not 50 Ohm. That is probably why you didn't get the perfect S11 and S22.View attachment 151585
i wrongly entered the impedance value in the simulator. Now i matched both in put and output, still the amplifier is not stable in that region. Can you help me to stabilize the transistor?
View attachment 151655
now i matched the transistor and added one 6 Ohm resistor in series with the input. Now the transistor is conditionally stable. I matched the transistor for maximum power so is it necessary to get S22 less than -10 dB ?
You still try to match S22.. Power Amplifiers don't use S22 to get max. Output Power.now i matched the transistor and added one 6 Ohm resistor in series with the input. Now the transistor is conditionally stable. I matched the transistor for maximum power so is it necessary to get S22 less than -10 dB ?
You still try to match S22.. Power Amplifiers don't use S22 to get max. Output Power.
Optimum Load Impedance has already been given in the datasheet, what you otherwise are looking for ??All you have to realize a Output Matching Circuit that present this Optimum Impedance to the Transistor..Input Presented Impedance is also given, design your PA under these circumstances..that's it..
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