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How does switched capacitors filter work?

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chichi

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how does switched capacitor filter work

i am very new in switched capacitors stuff,i know that SC filters are nowadays very popular,and also know that f and c can generate the resistance,but how did the switched cap generate the cut off frequency of filters?as far as i know,all the poles need R and C,where is the C come from in the switched caps?
 

ShaunZ

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chichi said:
i am very new in switched capacitors stuff,i know that SC filters are nowadays very popular,and also know that f and c can generate the resistance,but how did the switched cap generate the cut off frequency of filters?as far as i know,all the poles need R and C,where is the C come from in the switched caps?

There ARE capacitors in switch-cap filters. Since you know the frequent capacitor charging process acts as the resistance, the capacitor next to the "resistor" are the C in RC time and thus cut-off frequency.

Not all the caps "generate the resistance".
 

chichi

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u mean ,it's some caps in the switch for example,or the switched cap itself,if the RC time is 1/f,then divide R,we get that C,thus switch cap itselp,sorry,i did not quite get u
 

LvW

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Hi chichi !

There are lots of papers and other contributions to find in the internet about SC circuits. The principle of R replacement by a switched (periodically loaded and deloaded) capacitor is not hard to understand.
As one example, have a look at the document attached.
Regards and good luck.
 

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