Why do we need an amplifier in analog filter?

[tran]

Hi all,
In analog filter circuit, I see there is an amplifier at the output of the filter.
Can someone tell me why we need the amplifer. Can we use the output of the filter directly. Is there better than if we use an amplifier ?
In PLL , there is also an amplifier after the low pass filter. Can somenone explain for me why we need the amplifier after the filter ?
Thank you very much.
Tran

 

[klj55888]

analog filter

Because the FILTER have in band lose

 

[sachinagg77]

Re: analog filter

Following may be the reasons for the use of amplifiers:

1. To provide additional gain
2. To isolate the filter or the PLL from the excessive loading effect of the next stage.

I hope I could be of some help.

 

[venkateshr]

Re: analog filter

i agree with sachin. gain factor and averting the loading cud be the reasons .