ask about active filter

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Hi,
Can anyone tell me that an active filter needs a tuning circuit or not?
As I know, a gm-c filter needs tuning circuit, and I don't know if active filter needs?

Thanks.
B.R
 

Active filters that use RC elements need to have some tweaking of the values unless you use 1-5% tolerance components and the filter response is not that critical.
 

in active integrated filters like Gm-C , enhanced Q filters ,, the tolerance in the integrated components can reach 30% so the filter response will be varied , so u need to implement a tuning circuits to change currents in GM-C filters to get the actual response also in enhanced Q some PLLs implemented to auto tune the filter for the required transfer function

khouly
 

In active filter, R and C value may vary with process ,so trimming circuit may be needed to trim bandwidth.
 

trimming is necessary for active filter
 

hi
If the filter order > 3, there may have many R and C, how do I know to trim which element?
Any paper or book talk about the active filter's tuning/trimmig?

Thanks a lot.
 

U could trim the current bias of Gm, in Gm-c configuration.
 

you can trim either R or C, but probably not both.
 

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