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Why don't PAE vs PT (Total Power) measurements agree?

FormerMember
FormerMember

Hello,

I'm tuning an NXP LDMOS FET model in Microwave Office.  When my Vds current is about 20A at 12V, my output power on port 2 measured by the "PT" Total Power measurement shows ~100W (which is our optimization target).  

Here is the part I don't understand:  Why does PAE show about 75%?    Shouldn't 100W/240W have a PAE of ~41%?

Port 1 (Pin) is 17dBm, so 0.050 Watts, a negligible amount. 

(Pout-Pin)/Pdc == (100-0.050)/240W == 0.416.

What am I missing here?

Thanks for your help!

-Eric

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  • FormerMember
    FormerMember

    Well, I've stripped it down to a single FET: Vds is 12V, Ids is 7.6A (91.2 W). PORT1/Pwr input to the FET is 36dBm (4W).  PT(PORT_2) says 15W, and PAE says 72.5% Efficient. The math for PAE just doesn't match the numbers. This is a bug, either in my understanding or in the program---I'm just not sure which. 

    I'm not sure what to do next, any help would be greatly appreciated!

    -Eric

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  • FormerMember
    FormerMember

    Well, I've stripped it down to a single FET: Vds is 12V, Ids is 7.6A (91.2 W). PORT1/Pwr input to the FET is 36dBm (4W).  PT(PORT_2) says 15W, and PAE says 72.5% Efficient. The math for PAE just doesn't match the numbers. This is a bug, either in my understanding or in the program---I'm just not sure which. 

    I'm not sure what to do next, any help would be greatly appreciated!

    -Eric

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