Why the higher is the gain the better is the SNR performance?

[chang830]

Hi,
The noise and signal are amplified by the same gain.Why the higher gain, the good SNR performance?

thanks

 

[stober]

noise and gain

Noise is not only come from the input of your amplifer, but also from inside of your amplifer, which is generated by transistors resistors and so on in the amplifer. With higher gain, the second parts contribute less for snr.

 

[xischaune]

Re: noise and gain

Also every component has an operating range...
assuming noise power spectral density to be constant, the amplifier only enhances noise of its own range...whereas the average value of noise remains more or less the same... that is y the SNR improves

 

[Sudhir.K.A]

noise and gain

hi all,
i guess differential amplifier provides common mode noise rejection too. which will definitely result in high SNR.

regards,
Sudhir.K.A

 

[chang830]

Re: noise and gain

hi dear all,
Someone told me that the higher gain means the kower bandwidth, then the total integrated noise decreases,so the improvment of SNR.

Pls. comments!

 

[boooser]

Re: noise and gain

hi dear all,
Someone told me that the higher gain means the kower bandwidth, then the total integrated noise decreases,so the improvment of SNR.

Pls. comments!

I guess you mean the gain bandwidth.
For a amplifier gain*bandwidth=GBW

So large gain will low bandwidth if other condition remains the same.

 

[obovolo]

noise and gain

for simple output capacitor dominant one pole system, the higher output real part, the higher time constant, and therefore bandwidth is lower

 

[jinhaozi]

Re: noise and gain

refer you to the D. M. Pozar's Microwave Engineering

 

[haytham]

Re: noise and gain

Your amplifier will boosts the noise in its BW.
You could decrease the nosie level in your system by using a smart decoupling caps on supplies, differntial toplogies, ground shielding, empedance matching ......

Thanks

 

[wanily1983]

noise and gain

i agree with stober, high gain only can reduce the noise caused by the second stage and the third ....

 

[zenisle]

noise and gain

I agree with stober, noise coming from opamp self is not increased by gain.