# Help design circuit from transfer function

Discussion in 'General Electronics Discussion' started by pas2007, Sep 25, 2015.

1. ### pas2007

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0
Sep 25, 2015
Hello i am new to this forum.

I want to design a circuit with 5 opamps that implements this function transfer: G(s)=10/[(s+1) (s+5)]

it must be like this: https://www.dropbox.com/s/opsaabvrvighvqm/opamp.JPG?dl=0

Thank you

2. ### Harald KappModeratorModerator

10,771
2,427
Nov 17, 2011
Why does it have to be like this? Is this an assignement or homework? In that case I'll transfer it to the homework forum.

Write that equation as: G(s)=10 * 1/(s+1) * 1/(s+5) and you'll see that it has three terms:
10 = gain, can be obtained by a simple gain stage or integrated into the filter stages by giving them gain.
1/(s+1) = 1st order low pass filter
1/(s+5) = 1st order low pass filter
Multiplying these 3 terms is equivalent to a series connection of the 3 equivalent subcircuits.
The 1st order low pass filter is described e.g. in the Wikipedia - I guess that's where you took the image from and you could have linked to the Wikipedia article directly instead.

The issue is being discussed in detail e.g. here.

3. ### pas2007

2
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Sep 25, 2015
Thank you for the theory.
It is not a homework but a professor of mine asked me to bulid a ''silly'' circuit with 5 opamps for educational purpose.