DC load line of amplifier
I have a self-designed amplifier and need to find a load line to get higher output power. I use ADS for simulation. Does anyone have an example or know how to start?
Thanks,
You probably need to create more extreme action in your transistors. Bias them so they create larger swings of voltage and current. Is this correct? Make sure they are biased to correct amounts, that is, so the device conducts in a range which is (a) just above its minimum and (b) just under its maximum.
Reduce resistors in emitter legs, to increase sensitivity.
Do you have an N-device at the high side with a positive polarity supply? If you wish to turn the transistor on fully, you must bias it with an input signal whose amplitude is as great as your desired output voltage. (The same applies for a P-device in a symmetrical position with a negative supply.)
Is your amplifier class A? This configuration is fine for low power (example, pre-amp stage), but if you want high power then you should consider another topology.
If you are using mosfets instead of transistors, then translate the terms accordingly.
Find max. Id/Ic and Vcc/Vdd from data sheet and draw a straight line between Idmax and 2Vdd on a scaled chart.This is your Load Line.
Obtain IV curves in ADS and define your OP on this line that crosses one of the IV curves, this is your OP for A-Class PA.
Take precautions to put some safety margins and start to design.
There is a very nice Design Guides for PAs, use them to go forward..