How to remove ripples from Chopper stabilized Opamp?

[vrvadodariya]

When we will design a chopper stabilized amplifier, due to offset, some ripple of the same frequency as the chopping frequency will be generated at the output. How many ways are there to remove this ripples?
I am in search of some useful material regarding this.

 

[KlausST]

Hi,

the best is to avoid the ripple, so to make it as small as possible. Then the effort to attenuate it is minimal.

If you want to attenuate it with external circuit, then first you need to know all the frequency componets it contains, and their magnitude.
After that you can decide how to suppress it.

Do you think of:
* analog passive filters
* analog active filters
* digital filtering?

Klaus

 

[kpc]

Hi,

Basic idea of chopping is upconverting signal to the odd harmonics of chopping frequency. However, due to the finite bandwidth of the amplier, some unwanted spurs emerge at even harmonics of the chopper frequency. You should filter them out. One good referance paper about noise suppression of these circuits is the Enz's famous paper which is named as "Circuit Techniques for Reducing the Effects of Op-Amp Imperfections: Autozeroing, Correlated Double Sampling, and Chopper Stabilization". You can find it in IEEE Xplore.

 

[vrvadodariya]

Actually I am trying to avoid it earlier only. So For that immediately after 2nd mixing stage, I have added SC notch filter. But I am not getting much advantage. So I wanted to know about some different effective methods.
I cannot use external circuit.