Regarding amplifier efficiency

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DC power = AVERAGE DC current times DC supply voltage.

Load power = RMS current squared times load R.

If load is not pure R, you have issues.

.... Phil

Only in Class A is the input power constant. In Class AB and B, the DC current varies according to the RF excitation level.

The DC power implies an average input over the RF cycle. Your amplifier should have power supply filtering getting rid of the RF from the DC feed.

Please post the .asc file, so we can see what you're doing.

As I use HSpice and Ngspice, I am sorry I cannot supply the .asc file. I would be glad to provide the text netlist.

I have power supply filtering. The DC power supply and TF BJT sub-circuit is as follows(I hope the diagram is not too complicated)

VCC--/\/\--RFC inductor--BRF92A collector | Rc | | |

--- ---- DC blocking cap

--- Cap ---- | GND

A current meter is inserted between Rc and RFC inductor to measure DC current from VCC.

Yes, there are flaws. You said it was class B, implying "large signal." This is non-linear. It doesn't have "s-parameters" on the output because s-parameters are small signal parameters that presume *linearity*.

You said it was class B, but then biased it as if it was class A, for "s parameters." This makes no sense, as evidenced by your results when you drove it with a signal. The quiescent bias current of an undriven class B amp approaches zero.

"Impedance" is also a linear small signal assumption. The output of a non-linear amp does not have an impedance, strictly speaking. You should, as a first order approximation, be "load line matching," not "impedance matching.

Thank you very much for pointing out the errors in my reasoning.

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" Garbage in = garbage out ".

.... Phil

On a sunny day (Wed, 2 Oct 2019 20:53:37 -0700 (PDT)) it happened amal banerjee wrote in :

From a practical circuit POV the current meter should be on a not-RF active point, if you are in the point betwwen Rc and RFC, then the current meter's capacitance to ground and test lead inductance will completely change the complex Rc RLC to something equal or worse than:

L parasitic Rc-- L---L---RLC-- collector | === C parasitic | /// Freak! it may even oscillate.

Not in spice, spice assumes a perfect 'meter' IE spice lies.

So in practice it will suck due to internal meter impedance and lead impedances etc, making the whole test useless at 500 MHz. so that leaves this measuring method: V ---I meter---Rx --- RLC --- collector | | === --- --- --- | | added big RF decoupling capacitor (IE 22 nF LOL) /// ///

I guess y'all know that but...

Oscillating - or different impedance circuits may have a very different current draw....