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Port impedance affects NF?

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Julian18

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Hi, there:
I am using HspiceRF to simulate a LNA, I just want to know whether or not does the output port impedance affect the NF calculation, or is the output port impedance specified in port statement noiseless?

TIA.

Julian
 

Dear Julian18,
Variations in output port impedance doesn't affect the NF calculation.
Variations in input port impedance does affect the NF calculation.
 

i think it will affect , if u designed the output matching network to 50 ohm , and u changed the port to 100 ohm , the gain of the amp will decrease , and then the noise figure will increase , so u need to test the amp with the matching for the new port

khouly
 

khouly said:
i think it will affect , if u designed the output matching network to 50 ohm , and u changed the port to 100 ohm , the gain of the amp will decrease , and then the noise figure will increase , so u need to test the amp with the matching for the new port

khouly
Click to expand...

Hi, Khouly
But we can just compute the NF by using the Input referred noise voltage/current (knowing their correlation coefficient) and the source noise, then, the NF calculation is totally independent of the output load. Can u explain that?

Thanks

Julian

Added after 38 minutes:

By the Way, Does anyone here know the algorithm to calculate Ycor, Zcor(I dont know what Zcor is, the reciprocal of Ycor???) in HspiceRF
 

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