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Design >> RF Design >> basic doubt
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Message started by sivacha on Dec 14^th, 2006, 6:26am

Title: basic doubt
Post by sivacha on Dec 14^th, 2006, 6:26am

In RF design, we consider the load as port( dc source) and the port resistance as the load.
I dont understand why can't we consider direct resistance instead of using port??

Thank You,
Siva.

Title: Re: basic doubt
Post by Ken Kundert on Dec 14^th, 2006, 8:02am

You can, but if the source voltage is zero, they are equivalent. The port is only needed if you want to measure the s-parameters. It is used when computing s12 and s22.

-Ken

Title: Re: basic doubt
Post by aaron_do on Dec 14^th, 2006, 5:27pm

I'm not 100% sure but I think the output port resistance is de-embedded from the noise figure...anyone know for sure? i.e. if you use a 50 ohm resistor in simulation you will get different results than if you use a port...

Aaron

Title: Re: basic doubt
Post by Ken Kundert on Dec 14^th, 2006, 11:17pm

If you tell the noise analysis that the resistor is the load as you would with the port, then the results are identical.

-Ken