Continue to Site

Noise Figure

Status
Not open for further replies.

zxcv2201

Member level 1
Member level 1
Joined
Dec 4, 2021
Messages
36
Helped
0
Reputation
0
Reaction score
0
Trophy points
6
Activity points
392
I conducted a simulation using the AFE + mixer structure.
(At this time, the mixer's RF and LO frequencies were the same)
In this case, I have one question.

The total gain of AFE and LNA is about 30dB, and NF is 4.6dB.
I checked NFdsb at DC, and I think it has a high value of 52dB due to DC noise.

As a result of the simulation, the desired result graph was obtained, but there is a question as to why the result is obtained properly despite the mixer's high noise figure.

In my personal opinion, I interpreted it as follows :
According to the noise figure equation, the NF of the mixer is divided by the gain of the front stage. Since the gain values of AFE and LNA are large, I think the result was achieved because the influence of the mixer's NF was reduced.

I wonder if this interpretation is correct.
 

Your assumption is correct.
For example if you have 3 cascaded stages: LNA=4dB_NF 15dB_Gain, Mixer=9dB_NF 8dB_Gain, and IF-amp= 10dB_NF 20dB_Gain, the total noise figure will be 4.44dB and total gain 40dB.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top