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Simulators >> Circuit Simulators >> power delivered to load - pss analysis
https://designers-guide.org/forum/YaBB.pl?num=1235554986

Message started by tempora123 on Feb 25^th, 2009, 1:43am

Title: power delivered to load - pss analysis
Post by tempora123 on Feb 25^th, 2009, 1:43am

Hello,

I have set up a simple circuit. Port with 50 Ohm internal resistance and 100 Ohm load resistor. I would like to deliver fixed power to this resistor. Therefore, I set up 1dBm power property on PORT. With reflection coefficient of 0.333(3) (for voltage) or 0.111(1) (for power) I expect that the forward power increase factor is 1/(1-0.333^2)=1.125. This means the power delivered from PORT is 1.125dBm, reflected power is 1.125dBm * 0.111(1)=0.125dBm and the power delivered to load is 1.125dBm - 0.125dBm=1dBm.
When I run pss analysis and check Results -> Direct plot -> Main form -> Power and click on the terminal of the 100Ohm load resistor I get 0.4885dBm.
Can anyone explain this number?

Thank you.

Title: Re: power delivered to load - pss analysis
Post by subgold on Feb 25^th, 2009, 2:39am

hi,

i think your calculation is wrong. how come the power delivered from the PORT is larger than its own power? Also, you forgot to convert the factor into db.

the cadence result is simply 1dbm-10log(1-0.111).

Title: Re: power delivered to load - pss analysis
Post by pancho_hideboo on Feb 25^th, 2009, 5:52am

See http://www.designers-guide.org/Forum/YaBB.pl?num=1235497885/1#1

tempora123 wrote on Feb 25^th, 2009, 1:43am:

I expect that the forward power increase factor is 1/(1-0.333^2)=1.125.

Pinc=Pdis/(1-abs(Gamma)**2)
But power value set in port is Pinc not Pdis.
This is your misunderstanding.

tempora123 wrote on Feb 25^th, 2009, 1:43am:

When I run pss analysis and check Results -> Direct plot -> Main form -> Power and click on the terminal of the 100Ohm load resistor I get 0.4885dBm.

This 0.4885dBm is Pdis for Pinc=1dBm at Gamma=1/3.

Title: Re: power delivered to load - pss analysis
Post by tempora123 on Feb 25^th, 2009, 10:03am

Hello,

thanks for your replies. It seems clear now.

br