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# Applying a Transfer Function to an Opamp

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#### fethiyeli

##### Full Member level 4
Applying any Transfer Function to an Opamp

Hi everyone, i have an issue about applying a transfer function to an opamp. I know how to get transfer function for a given opamp circuit. Suppose we have a transfer function but we may add additional pole, zero etc to get stable system. I have been working on feedback system, PI, PD and PID controllers. For example, PID controller can have pole, zero and inverted zero or more. I have seen lots of PID opamp circuits but each are in different configurations. Even when i need to insert pole, zero etc to already found transfer function, i struggle how to apply the new transfer function to as opamp circuit. Adding pole,zero etc to transfer function, makes it harder to apply it to as opamp circuit. I mean how can i apply any transfer function i have found to an opamp circuit ?

I would describe the problem as "synthesis of transfer functions with OP circuits".

There are building blocks for active circuits implementing real and complex poles and zeros that can be found in analog design text books, also in books teaching s-domain (laplace transformation) circuit description. If you restrict the solution to real poles and zeros, the circuits are straightforward and can be easily constructed from the scratch. This would already serve most control system applications, eg. PID controllers. Complex poles and zeros are more used in filter design.

fethiyeli

### fethiyeli

Points: 2
Any practical s-domain transfer function is made up of denominator and numerator terms like (s+a). You only need to know how to create denominators and numerators. Refer to any books about classic control theory, you will find many neat solutions.

fethiyeli

### fethiyeli

Points: 2
Thanx. I will do some research. I may ask u an another question about it again.

search for "circuit and network synthesis". there are some courses in universities and very helpful for beginners.

fethiyeli

Points: 2