does Switch capacitor filter need antialiasing filter?

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fantaci

Joined: 28 Sep 2002
Posts: 59
Helped: 1

12 Aug 2005 7:19 does Switch capacitor filter need antialiasing filter?

I am confused.
Before switch capacitor filter, is antialiasing filter needed?

marshel

Joined: 10 Jun 2005
Posts: 49
Helped: 3
Location: China

12 Aug 2005 7:28 does Switch capacitor filter need antialiasing filter?

sure
you need an antialiasing filer

prabhu_psg

Joined: 04 Aug 2005
Posts: 17

12 Aug 2005 10:06 Re: does Switch capacitor filter need antialiasing filter?

Hi

Do we require any reconstruction filter at the end

Thanks

Prabhu

SkyHigh

Joined: 13 Jan 2005
Posts: 376
Helped: 51

12 Aug 2005 11:08 Re: does Switch capacitor filter need antialiasing filter?

prabhu_psg,

Reconstruction filter is used when you need to remove higher frequencies in the digital signal in order to retrieve your baseband signal and it is usually a LPF. Sometimes reconstruction filter is also called a smoothing circuit or smoothing filter.

It is unlike an anti-aliasing which is used to remove unwanted signals or suppress energies in high frequencies NOT of interest before further processing.

yibinhsieh

Joined: 25 Apr 2005
Posts: 196
Helped: 17

13 Aug 2005 10:40 Re: does Switch capacitor filter need antialiasing filter?

Prabhu wrote

Quote:

Hi

Do we require any reconstruction filter at the end

Thanks

Yes, usually we will use reconstruction filter after the SC filter. like audio DAC.

It will remove the high frequency noise and get a better THD.

Yibin[/quote]

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GDF

Joined: 11 Aug 2005
Posts: 175
Helped: 1

16 Aug 2005 17:33 Re: does Switch capacitor filter need antialiasing filter?

1)Do we need to calculate the THD before smoothing filter or after it?
2)If the answer is after the filtering, I'm confused the distorted signal
can be recovered by filter?