The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Mar 28th, 2024, 8:54am
Pages: 1
Send Topic Print
noise figure of passive circuit (Read 2429 times)
VNF
New Member
*
Offline



Posts: 8

noise figure of passive circuit
Jul 14th, 2015, 11:21pm
 
Hi,

It is shown in multiple places that noise figure of a passive circuit equals to the power loss.

My question is, theoretically (assuming no bandwidth issue), if the network is a simple capacitor divider, i.e. with voltage gain of 1/2, then the signal, along with the noise will scale by 1/2 altogether, therefore SNR_out should be the same as SNR_in, which leads to NF = 1.

so what am I missing here?
thanks,
VNF
Back to top
 
 
View Profile   IP Logged
bellona
New Member
*
Offline



Posts: 1

Re: noise figure of passive circuit
Reply #1 - Jul 18th, 2015, 9:31pm
 
The CAP divider is actually a impedance transformer, and ideally it introduces no power loss (Voltage halved with Current doubled), so the NF should be 0dB (F=1)
Back to top
 
 
View Profile   IP Logged
baohulu
Community Member
***
Offline



Posts: 43
china
Re: noise figure of passive circuit
Reply #2 - Jul 23rd, 2015, 11:59pm
 
I think you are right
Back to top
 
 
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2024 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.