What parameters to consider when calculating PA noise figure?

[lokesh anand]

hi everyone..,here i have some doubts regarding noise figure. i am designing power amplifier at operating frequency of 1000MHz. in order to caluculate the noise figure of the PA, which of these parameters should be considered? nf1 or nf2 or NFmin? what are the diffrences between them?

 

[metu]

noise figure

NFmin is the noise figure with optimum source matching.
NFi is the signal to noise ratio at input divided by signal to noise ratio at output(i)
I am not working on PA but for the amplifier design nf2 is considered.

 

[rfsurfer]

Re: noise figure

Not very often see NF in a PA design spec table though.

 

[khouly]

Re: noise figure

for power amplfier the noise figure is not an issue
the noise figure is always an issue for the LNA

in PA , the efficiency , the linearity , are the main spec's in PA design


Khouly

 

[ali_desidero]

Re: noise figure

hi everyone..,here i have some doubts regarding noise figure. i am designing power amplifier at operating frequency of 1000MHz. in order to caluculate the noise figure of the PA, which of these parameters should be considered? nf1 or nf2 or NFmin? what are the diffrences between them?

you are using ADS, right? you should use nf(2) to simulate NF of your PA. As mentioned already by the others, NFmin is the minimum noise figure and depends on your source impedance (this is 50 Ohm in your case, I suppose). I don't know exatly what nf(1) is, but I think nf(1) is just a feature of ADS and gives SNRout/SNRin instead of SNRin/SNRout.

 

[Yahia Muhammad]

Re: noise figure

The noise figure in case of power amplifier is not an issue as it's not linear

 

[biff44]

Re: noise figure

Wow. The people posting that the noise figure of the transmit amplifier, and therefore the broadband noise that it outputs, is not an issue must not have worked on very many real life system!

 

[zechery]

Re: noise figure

According to ali_desidero

you are using ADS, right? you should use nf(2) to simulate NF of your PA. As mentioned already by the others, NFmin is the minimum noise figure and depends on your source impedance (this is 50 Ohm in your case, I suppose). I don't know exatly what nf(1) is, but I think nf(1) is just a feature of ADS and gives SNRout/SNRin instead of SNRin/SNRout.

If this is really the definition used in ADS, then we should use nf1 right?
I am having the same problem now.
But I am simulating NF for LNA.

 

[ali_desidero]

Re: noise figure

According to ali_desidero

you are using ADS, right? you should use nf(2) to simulate NF of your PA. As mentioned already by the others, NFmin is the minimum noise figure and depends on your source impedance (this is 50 Ohm in your case, I suppose). I don't know exatly what nf(1) is, but I think nf(1) is just a feature of ADS and gives SNRout/SNRin instead of SNRin/SNRout.

If this is really the definition used in ADS, then we should use nf1 right?
I am having the same problem now.
But I am simulating NF for LNA.

no, you should use nf(2), because F = SNRin / SNRout.