How to reduce the noise of a circuit?

[nxing]

noise reduction

Hello everybody,

Can anyone suggest some ways to reduce the noise of a cuicuit? ( I mean in general, not for a particular circuit)

Thanks

 

[barrybear]

Re: noise reduction

Your question is quite ambiguous , it is very dificult to answer as there are so many vereables.

Use the right components for the job.
Make sure you have the correct powersupply and decoupling.
Always match input and output impedences
stratechicly place components for minimal crosstalk.
screen well
ensure there are no earth loopes.

Barrybear

 

[guamak_menanak]

Re: noise reduction

you need to study the source of the noise such as flicker, thermal etc..
study the equation and you can find which parameter can be adjuct to lowering the noise...

for example...
to reduce flicker noise...you can increase the width of the transistor!

 

[suraj]

Re: noise reduction

Hello Friend,

Say we have a differentail amplifer. Input referred noise can be minimised by increasing the gm of the input transistor and at the same time reducing the gm of the load transistor.

Please correct me if I am wrong.
Suraj

 

[sunking]

Re: noise reduction

big current, low noise device, large device, and add cap

 

[Aser]

Re: noise reduction

1. Minimize the noise source.
Often this source operates as antenna.
Digital high current outputs spread the noise very well.
Therefore minimize the current in such outputs.
Freese the warm noise source, or minimize its resistance .
2. Make the signal immune to noise.
Such signal can be transferred through high current, low impedance wire.
Noise immune modulation can be used.
3. Signal and/or noise source screening.
Divide the digital and analog circuit feeding.

 

[chinboon]

Re: noise reduction

Hmmp... reduce noise in general? In which level transistor level or circuit level. If you are mentioning on circuit level you need to read books on it how they calculate noise and how to choose the right values for each components to reduce the noise. Any books have it example grey and meyer.

For transistor levels use channel length optimization technique which you find the input referred noise then differentiate the input referred noise against channel length of the input pair to find the minimum value.

To verify please make sure that your transistor simulation model is of BSIM3v3 and above.

Increasing current would not reduce noise. Why? Increase current increases gm which increases gain so meaning input refererred noise reduce. That is only true if your noise model have no current term. When you go into deep submicron and new BSIM models you notice that the flicker noise model is added with current term with power AF. Increasing the current can increase gain but indirectly you also increases the noise. gm increased by square root due to increase in current but your noise increased by power AF due to increase in current.

You need to make sure which gain (gm of noise) is increasing more to verify whether increasing the current of an op amp design would reduce noise.

 

[chinboon]

Re: noise reduction

Sorry i made a typo it should be gm or noise not gm of noise

 

[v_naren]

Re: noise reduction

How about using no resistors to implemnent your circuit!!