Need help in designing a cascaded bandpass filter

[hessa]

Hi everybody,
In our project, it's required to design a bandpass filter using a HPF and a LPF cascaded together
and Amplifiers are not allowed in the circuit
so the circuit should contain only R,L, and C.
The bandwidth and the center frequency were the only values given

The question is, HOW to get the other values for R, L and C?!!
What equations can be used to calculate these quantities with the the only given values (BW and Fc)???

I tried many things but it all failed

I appreciate your help!

 

[LvW]

Hello hessa,

are you really required to use a cascade of a passive HPF and a LPF ?
By the way: Which ORDER?
In this case, there must be a decoupling amplifier (buffer) between both stages.
But you are not allowed to use such an amplifier?
And what about DIRECT realization of a bandpass? Not allowed?

 

[audiomik]

Hessa
what you are asking is relatively commonly done for the 'Mid' section of Passive Crossovers used for Three Way Loudspeakers.

Have a look at how these are done for some ideas perhaps - there are a number of websites which contain calculators for these which you may find of use.

This link might be a start?
**broken link removed**

Mik

 

[LvW]

Hessa,

what Audiomik has suggested sounds appropriate. However, I don`t think you can calculate all the values by yourself for such a design.
Are you allowed to use tables with normalized values? (I presume: No).
However, if both parts (LP and HP) are of first order only, you do not need a buffer in between. Therefore my question: Which order?

 

[BradtheRad]

There are any number of solutions which yield a desired bandwidth and center frequency.

Suppose you start by selecting a value for any one of the components R or L or C. You can then derive the other two values.

The link below is a rather thorough introduction to passive filters.
RC, RL, bandpass, bandstop.
Cascaded HPF and LPF.
Mathematical formulas.
Schematics which show working component values.
Response graphs of sine sweeps.

http://www.faqs.org/docs/electric/AC/AC_8.html

 

[BradtheRad]

Hi all, can you please share me some courses on the design of LC filter ? if you have some courses or paper ?
i need this information soon

Recent thread about this topic:

https://www.edaboard.com/threads/288622/

Links to websites of electronics tutorials.

**broken link removed**

http://talkingelectronics.com/

http://www.4qdtec.com/

**broken link removed**

**broken link removed**

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http://www.circuits-city.com/

http://www.bowdenshobbycircuits.info/

http://williamson-labs.com/

http://www.repairfaq.org/sam/samschem.htm#schtoc

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'Filter Design in Thirty Seconds'

http://www.ti.com/lit/an/sloa093/sloa093.pdf

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Animated simulator with circuits showing basics and intermediate, analog and digital.

http://www.falstad.com/circuit/e-index.html