Frequency Response of Op amp Circuits

In summary: If you have the gain and input/output impedances, you can use the equations given to calculate the frequency response function. However, if you don't have all of that information, you may need to make some assumptions or use a different method to solve the problem.
  • #1
mzon13
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0
1. Homework Statement
For this problem, the diagram of the circuit is attached. It was assigned to find the frequency response function of the circuit.2. Homework Equations
E_o/E_i= -Zf/Zi3. The Attempt at a Solution
I know for the top branch of the circuit, it has a negative feedback loop so therefore its:
E_o/E_i = -Rf/Rin

The problem I am having is with the resistor connected to the non inverting input. Since it doesn't have a loop structure, I question what it's output is and how to account for that in my frequency response function. The only examples I have found are of differential amplifiers. However those have two resistors that end up being connected to ground. Any assistance is appreciated.
 

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  • #2
mzon13 said:
1. Homework Statement
For this problem, the diagram of the circuit is attached. It was assigned to find the frequency response function of the circuit.


2. Homework Equations
E_o/E_i= -Zf/Zi


3. The Attempt at a Solution
I know for the top branch of the circuit, it has a negative feedback loop so therefore its:
E_o/E_i = -Rf/Rin

The problem I am having is with the resistor connected to the non inverting input. Since it doesn't have a loop structure, I question what it's output is and how to account for that in my frequency response function. The only examples I have found are of differential amplifiers. However those have two resistors that end up being connected to ground. Any assistance is appreciated.

Welcome to the PF.

The resistor at the + input is just there to help balance out the parasitic input offset voltage due to the input bias currents. It is often omitted with CMOS opamps, since their input bias currents are so small. The value of the resistor at the + input is often the parallel combination of the Ri and Rf resistors.

So you should be able to ignore the resistor at the + input, IMO, for the purposes of calculating the frequency response of this circuit. Given that, how will you go about calculating the frequency response of this opamp circuit?
 
  • #3
How much info were you given about the opamp itself?
 

What is frequency response?

Frequency response is the measure of how an op amp circuit responds to different frequencies of input signals. It describes the circuit's ability to amplify or attenuate signals at different frequencies.

Why is frequency response important?

Frequency response is important because it allows us to understand how an op amp circuit will behave in different operating conditions. This information is crucial for designing and analyzing circuits.

What factors affect the frequency response of op amp circuits?

The frequency response of op amp circuits can be affected by several factors, including the circuit's components, the op amp's gain bandwidth product, and the feedback network used in the circuit.

How is the frequency response of an op amp circuit measured?

The frequency response of an op amp circuit can be measured by applying a sinusoidal input signal of varying frequencies and measuring the output signal. The resulting plot of output voltage versus frequency is called a Bode plot.

What is the ideal frequency response for an op amp circuit?

The ideal frequency response for an op amp circuit is a flat response, meaning that the circuit amplifies or attenuates signals at all frequencies equally. However, this is rarely achieved in real-world circuits due to limitations of components and op amp specifications.

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