A band pass filter which doesn't alter my signal

Thread Starter

nyasha

Joined Mar 23, 2009
90
Okay, so l want to design a band pass filter that doesn't attenuate my signal. Is that possible. I want it to allow frequencies between 1khz and 3khz. I have tried to make one, but it ends up with my signal getting attenuation. Any hints on how l can achieve this ?
 

SgtWookie

Joined Jul 17, 2007
22,210
If you're going to make a passive filter, you'll have some loss. The better you tune the filter, the less loss you'll have.

Here's a pretty decent one I threw together; it's a modification of a Cauer.

See the attached for a plot of the transmission (S21) and reflection (S11).
At 1kHz, the signal is about -0.443dB, at the center, around -0.223db, and @3kHz, -0.288dB

 

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Thread Starter

nyasha

Joined Mar 23, 2009
90
if not active, then tank circuit is usually better than regular passive filter implementation in terms of attenuation.

http://www.allaboutcircuits.com/vol_2/chpt_8/6.html#02124.png
I think the tank filter which shorts out signals within the frequencies l do not like is what l will try to design given the parts l have which include only one 10mH inductor. I will post my multism circuit for you guys to critique. Thanks very much for the hints.
 

Papabravo

Joined Feb 24, 2006
12,493
You could always put an adjustable amplifier in front of or after your filter. This is called buffering and prevents one filter from loading a previous or subsequent stage. Most engineers, realizing the benefits of buffering, do it without giving the insertion loss a second thought.
 
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