I have designed a PA,when i increase the input power by 1dB,the outpower increased 1.5dB,i can not explain this result,who can tell me why this occurs and how to improve this!
What do you use to measure ?? Power meter or SA ??
If you're using Power Meter, the equipment will measure the total power including harmonic powers.
Therefore if your amplifier goes into saturation, harmonics will be increased quicker than main carrier so power seems to be increased bacause of total power.
I have designed a PA,when i increase the input power by 1dB,the outpower increased 1.5dB,i can not explain this result,who can tell me why this occurs and how to improve this!
patriot
my test result is true and correct!i use the power meter 437B and the source E4432B!but gain expasion occured,so i can't give an logical explain!
patriot
my test result is true and correct!i use the power meter 437B and the source E4432B!but gain expasion occured,so i can't give an logical explain!
Actually, the active device doesn't have a constant gm, which also changes with bias point. So if you want to get a constant gain, maybe it's better increase a little the bias point.
Please refer to: Cripps, RF Power Amplifiers for Wireless Communications, 2ndED, chapter 3.5 Reduced Conduction Angle Mode Analysis and the figure 3.10.