Understanding the Function of a Narrow Band-Pass Filter and its Transitions

[electronic engineer]

I was aksed to study and draw the transitions of narrow band-pass filter function gives as :

Av(s)=Ao (s*Wo/Q)*(1/(s^2+s*Wo/Q+Wo^2) ; S Laplace transform


where: Wo is central frequency

Q quality factor Q=Wo/WH-WL=Wo/BW

WH &WL are high cut-off and low cut-off frequency respectively

just need some hits !

thanks in advance!

 

[Corneo]

Whats your problem? Determine the center, upper, and lower cut off frequencies?

 

[berkeman]

You can use Excel to plot it to get a feel for what it looks like, although it will plot best in log-log (log frequency on horizontal axis). Start with a Q=1 plot, then overlay Q=10 and Q=0.1 plots. Pick some generic Wo frequency for starters, like 100kHz or something.

What textbook are you using? Most texts should have a good discussion of the BPF transfer function and the effect of the Q factor. If your text is lacking, there are lots of resources on the web. I googled bandpass analog filter transfer function tutorial, and got lots of good hits. Here's one -- scroll down to some of the Filter Design articles:

http://www.circuitsage.com/filter.html

 

[electronic engineer]

oh ,berkeman thanks you for your googling , sometimes i google for various things but I find out that you have good experience in selecting keywords, is there any generic rule to precisely find what you need through google or that just depends on repitation?!

thanks a lot!

 

[berkeman]

Mostly getting better at google involves trying out stuff, and learning some of the advanced features. Check out the advanced feature list sometime -- I forget if google supports the "near" keyword, for example. Only some search engines do. Using quotes around multiple word phrases helps a lot in cutting down on the extra search hits that are displayed. And using the + sign before required terms in the search also helps a lot sometimes.

Also, I've lately found the keywork "tutorial" to be real helpful in finding info in the form that helps folks here on PF.

 

[electronic engineer]

Check out the advanced feature list sometime -- I forget if google supports the "near" keyword, for example.

I didnn't find that feature but there's another feature for finding pages similar to a webpage we detect , and find pages that link to the page!


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