Advantages of Switch Capacitor Filter vs RC Filter

[Syafiq]

Hi

What are the advantages of Switch Capacitor Filter vs RC Filter? Are Switch Capacitor Filters commonly used in today's era? Or are most common devices still relying on RC Filters? I am working on a project and really need to make RC Filter look "bad" in today's context, assuming Switch Capacitor is not so commonly used yet. Thanks!

 

[moffy]

Switched capacitor filters are tuneable by a clock frequency. They are also usually complex multipole filters, e.g. 8 pole chebyshev etc. which is pretty hard with RC because tolerances of the components and values are difficult. But they are very noisy compared to RC because of all the switching. This is the main reason not to use them.

 

[Winterstone]

Switched capacitor filters are tuneable by a clock frequency. They are also usually complex multipole filters, e.g. 8 pole chebyshev etc. which is pretty hard with RC because tolerances of the components and values are difficult. But they are very noisy compared to RC because of all the switching. This is the main reason not to use them.

But this does not mean that they are not used in practice. There are many filter-IC`s commercially available.
And that is another advantage: Ability to realized in integrated technology - to be controlled externally by a clock frequency.
Another advantage: It is possible to realize very LOW pole frequencies (down to 0.1 Hz), which is a problem in RC techniques.

 

[WTP Pepper]

Switched Cap Filters are great if you require a high roll on/off or a high Q bandpass filter in a single package. The fact they are clocked means you can tweak the final frequency.

However as said, they are noisier than an RC filter but depending on your application that may not be an issue.

You also need to prefilter using an anti-aliasing filter to prevent unwanted signals appearing in-band.

I used the MF10 many years ago to pick out a tone in an audio channel. it worked fine.

https://www.electro-tech-online.com/custompdfs/2013/06/mf10-n.pdf