Why is the output of the integrating op amp reversed?

In summary, the conversation discusses the output of an integrating op amp and the confusion surrounding its behavior. The blue line represents the input signal and the orange line is the output signal. The question is raised as to why the output signal has the opposite sign of what is expected for an integrator. The possibility of the voltage being applied to the inverting input is considered, but even after flipping it, the output remains the same. It is then explained that the op amp holds its inputs equal and the input to output reversal of polarity is necessary for the circuit to function properly. After the initial transient, the output moves in the correct direction. A resource is also provided for further understanding of op amps.
  • #1
Cantstandit
30
0
Hello,
I'm having problem understanding the output of the integrating op amp.

https://www.dropbox.com/s/djpg0uhi465ot86/download2.png
https://www.dropbox.com/s/djpg0uhi465ot86/download2.png

https://www.dropbox.com/s/p9bp9tlyykhjtvf/download.png
https://www.dropbox.com/s/p9bp9tlyykhjtvf/download.png
(hope you can see that, I can't see it on my preview)

The blue line is input, orange is output. So if it's supposed to integrate, surely output signal has a wrong sign, doesn't it? If the integral is the area under the square signal, there should be linear increase when the signal is positive and linear decrease when it's negative, yet it's the other way around, why? I'd thought it was because my voltage had been applied to the inverting input of the op-amp, but even when I flipped it, it stays the same...
 
Last edited:
Engineering news on Phys.org
  • #2
Remember you have an inverting amplifier there.
The opamp will hold its inputs equal, and +input is at zero.
Therefore whatever current is pushed into summing junction through R1 must get pulled back out through C1&R2,,,,
,,,so an input to output reversal of polarity is nessary.

After the initial transient (power up i presume?) , output looks like it moves in right direction.

http://www.ti.com/ww/en/bobpease/assets/AN-31.pdf
 
Last edited:

1. What is an op amp and how does it work?

An op amp, or operational amplifier, is an electronic component used to amplify and manipulate electrical signals. It typically consists of an inverting and non-inverting input, an output, and a power supply. It works by amplifying the difference between the two input signals and producing an output signal based on the ratio of the input signals.

2. What is the significance of integrating op amps in circuit design?

Integrating op amps are used in circuit design to perform mathematical operations such as integration, differentiation, and summing. They can also be used to filter and amplify signals, making them a versatile component in many electronic applications.

3. How do you choose the right op amp for a specific circuit?

The right op amp for a specific circuit depends on various factors such as the required gain, bandwidth, input and output impedance, and power supply. It is important to carefully consider the specifications and characteristics of the op amp to ensure it meets the needs of the circuit.

4. What are the common challenges when integrating op amps in a circuit?

Some common challenges when integrating op amps in a circuit include noise, stability, and offset voltage. Noise can interfere with the accuracy of the output signal, stability issues can cause the op amp to oscillate, and offset voltage can result in errors in the output signal. It is important to consider these factors and take measures to minimize their effects.

5. How can negative feedback be used to improve the performance of an op amp circuit?

Negative feedback can be used to improve the performance of an op amp circuit by stabilizing the gain and reducing distortion. It also helps to minimize the effects of external noise and offset voltage. By using negative feedback, the op amp can be configured to act as a linear amplifier, making it more suitable for precise measurements and control applications.

Similar threads

What's wrong in my LTspice simulation of an Op-Amp integrator circuit?
    • Electrical Engineering
Replies
9
Views
4K
Op-amp compensation of cascade fudges audio signal oddly
    • Electrical Engineering
Replies
3
Views
797
Confusion on: High Pass Filter at Op Amp Input
    • Electrical Engineering
Replies
6
Views
1K
Design of an Op Amp Circuit for Voltage Amplification
    • Electrical Engineering
Replies
9
Views
3K
Equal Input Voltages on Op-Amps
    • Electrical Engineering
Replies
4
Views
1K
Inverting a signal up to 100mV using op amps
    • Electrical Engineering
Replies
6
Views
1K
Noninverting op amp doesn't work on a highly resistive load
    • Electrical Engineering
Replies
31
Views
3K
[help] understanding Op-Amp frequency characteristics
    • Electrical Engineering
Replies
3
Views
1K
Any advice to make this Op-Amp temperature controller circuit work?
    • Engineering and Comp Sci Homework Help
Replies
34
Views
2K
How does an Op-Amp "find" equilibrium (w/ Negative Feedback)?
    • Electrical Engineering
2
Replies
50
Views
6K

Hot Threads

Recent Insights

Back
Top