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bandpass active filter Current feedback

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dragon_03

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CFA

i want to design bandpass active filter Current feedback (CFA) with the center frequency 50MHZ by using sallen-key topology.

i would like to know which OP amp i have to use and its possible to increase the center frequency to 100MHZ
 

Re: CFA

dragon_03 said:
i want to design bandpass active filter Current feedback (CFA) with the center frequency 50MHZ by using sallen-key topology.
i would like to know which OP amp i have to use and its possible to increase the center frequency to 100MHZ
Click to expand...

As indicated by you (name of the topic) a CFA type seems to be appropriate with a UGB of at least 700...800 MHz.
Concerning the second question, do you mean frequency tuning or fixed design?
 

Re: CFA

dragon_03 said:
i want to design bandpass active filter Current feedback (CFA) with the center frequency 50MHZ by using sallen-key topology.

i would like to know which OP amp i have to use and its possible to increase the center frequency to 100MHZ
Click to expand...

You cannot put reactive components (capacitors or inductors) in the feedback of current feedback amps.

Keith.
 

Re: CFA

keith1200rs said:
You cannot put reactive components (capacitors or inductors) in the feedback of current feedback amps.
Keith.
Click to expand...

Hi keith,

I am afraid you have overlooked the fact that in Sallen-Key (S+K) structures the CFA is used as a noninverting amplifier without any capacitive feedback. The S+K topology is the only one which allows CFA`s .
 

Re: CFA

LvW said:
keith1200rs said:
You cannot put reactive components (capacitors or inductors) in the feedback of current feedback amps.
Keith.
Click to expand...

Hi keith,

I am afraid you have overlooked the fact that in Sallen-Key (S+K) structures the CFA is used as a noninverting amplifier without any capacitive feedback. The S+K topology is the only one which allows CFA`s .
Click to expand...

My mistake. Thanks. Sorry if I caused any confusion to anyone.

Keith.
 

Re: CFA

keith1200rs said:
................
My mistake. Thanks. Sorry if I caused any confusion to anyone.

Keith.
Click to expand...

Don't mention it.
Regards
 

Re: CFA

LvW said:
keith1200rs said:
................
My mistake. Thanks. Sorry if I caused any confusion to anyone.

Keith.
Click to expand...

Don't mention it.
Regards
Click to expand...

I must admit, when I get to 50MHz or above I would probably be looking at passive LC filters, but it depends on the applications.

Keith.
 

Re: CFA

keith1200rs said:
...........

I must admit, when I get to 50MHz or above I would probably be looking at passive LC filters, but it depends on the applications.

Keith.
Click to expand...

Yes, I agree - 50...100 MHz are rather high for active filtering. However, it`s possible with high performance CFA`s or OTAs.
vW
 

Re: CFA

i would like to know which "current feedback OP AMP" work at high frequency
:?:
 

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