Gain and noise calculation

[Giowizzy]

***Please break it down with more info as possible...Greatly appreciate.


Suppose a receiver consists of an low noise amplier with a gain of 30 dB and noise gure of
2 dB, followed by a second stage of amplication of another 20 dB with a noise gure of 10
dB.
(a) What is the total noise gure and gain of the system?
(b) Suppose a 10 dB attenuator is placed at the input of the LNA. What is the resulting
overall gain and noise gure?
(c) What if the attenuator is placed at the output of the LNA?

 

[Sanchayan]

Re: Can you solve this problem?

From my understanding
a. Values in db add up so gain would be 50dB and noise gain of 12dB.
b. Attenuator would result in -10dB addition. So gain 40dB and noise gain 2dB.
c. Answer would be same as b

 

[mister_rf]

Re: Can you solve this problem?

Read here:
Noise figure - Wikipedia, the free encyclopedia
Error 404 - Page Cannot Be Found
Noise Figure Calculator | em: talk


Cascaded Noise Figure & Noise Temperature Calculation Equation Formula - RF Cafe

 

[zorro]

Re: Can you solve this problem?

Dear Giowizzy,

the best advice is that you try to solve your assignments by yourself.
You risk to get wrong answers, like in post #2.
Regards

Z

 

[Sanchayan]

I considered the noise figure as noise gain. My mistake.