Designing a Cascaded Fourth-Order Chebyshev Lowpass Filter

Thread Starter

jeremiah.pe

Joined May 18, 2021
3
Hello, Me and my friend are trying to follow the tutorial lesson from
http://www.emagtech.com/wiki/index....esigning_a_Second-Order_Active_Lowpass_Filter
and we couldn't really replicate doing the fourth-order chebyshev lowpass filter.
The results didn't really match what was in the webpage and we think that our values are the same as they have set in the webpage.

1621357167160.png

Can anyone please guide us on how to replicate this and work out the right results?
Any help would be greatly appreciated.
 

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Papabravo

Joined Feb 24, 2006
16,160
I see places (4-way intersections) where there are no connection dots and there should be. What you should do is avoid 4-way intersections altogether. Break the wire in the vicinity of the intersection and make two 3 way intersections.

EDIT:
1. I redrew the wires connecting C1 and C3 to the opamp outputs so the connection dots would show up.
2. I moved the power supply wires out of the main field of view and replaced them with the Net name VCC for the positive supply and VEE for the negative supply. I didn't try to run you schematic because you have coded an explicit path in the .lib statement which I cannot replicate.

Have fun with your rockets.

I've also included a bonus file for you. It is a collection of 5th order Chebyshev Transfer functions using the Laplace operator with the Voltage Controlled Voltage Source so you can see an example to compare your results with. You just need to work out the factorization of you 4th order transfer function.
 

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Last edited:

MrAl

Joined Jun 17, 2014
8,251
Hello, Me and my friend are trying to follow the tutorial lesson from
http://www.emagtech.com/wiki/index....esigning_a_Second-Order_Active_Lowpass_Filter
and we couldn't really replicate doing the fourth-order chebyshev lowpass filter.
The results didn't really match what was in the webpage and we think that our values are the same as they have set in the webpage.

View attachment 238926

Can anyone please guide us on how to replicate this and work out the right results?
Any help would be greatly appreciated.
This looks like two second order filters so it will factor into two second order equations which will make any solutions for any component values easier.
 
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