In the world of electronic circuits, an operational amplifier (op-amp) is a key device. It is a powerful amplifier that can boost signals and has two inputs and one output. These inputs are called inverting input and non-inverting input. An inverting input is marked with a negative (-) sign, and a non-inverting input is marked with a positive (+) sign.
There are two main types of Op-Amp configurations:
- Inverting amplifier
- Non-inverting amplifier
This article will explain the comparison between inverting and noninverting amplifiers. But first, let’s see what each one does.
What Is An Inverting Amplifier?
An operational amplifier that produces an output signal 180 degrees out of phase with the input signal is known as an inverting amplifier.
One advantage is that an inverting operational amplifier is easy to convert to a non-inverting amplifier by changing the input connections. The amplified output signal has a negative phase while the input signal is positive, making the inverting amplifier the most commonly used type.
The diagram below represents an inverting amplifier circuit. It is clear from the diagram that the feedback signal is provided by the operational amplifier to perform the closed-loop operation.
In closed-loop operation, the feedback signal provided by the operational amplifier increases the accuracy of the operation, especially when it is negative.
We can calculate voltage gain by applying KCL to inverting nodes:-
Voltage Gain(A) = Vout/ Vin = – Rf/Rin
What Is A Non-Inverting Amplifier?
In a non-inverting op-amp, the input and output signals are in the same phase.
Thus, if the input signal has a positive phase, the output amplified signal also has a positive phase. Similarly, if the input signal has a negative phase, the amplified output signal also has a negative phase.
Feedback is given at the inverting terminal only if the input signal is at the non-inverting terminal, resulting in negative feedback.
Using the following expression, we can get the closed-loop gain of a non-inverting amplifier:-
Voltage Gain(A) = Vout/Vin = (1+ Rf/Rin)
Inverting Vs Non-Inverting Op-Amp: Pros And Cons
| Feature | Inverting Op-Amp | Non-Inverting Op-Amp |
|---|---|---|
| Voltage Inversion | Ideal for signal inversion or phase-shifting tasks | Perfect for amplifying and buffering signals without phase shifting |
| Input Impedance | The input impedance is set by the input resistor, which allows for ease of control | Extremely high input impedance reduces the impact on the signal source |
| Common Mode Rejection Ratio (CMRR) | Lower CMRR is less effective at filtering common-mode noise | Better for applications requiring high CMRR, strong common-mode noise rejection |
| Negative Gain | This can result in negative benefits, which are not always worth it | Always provides positive gain, unsuitable for situations requiring inversion |
| Feedback Configuration | A feedback resistor connects the inverting input to the output, Increasing the noise | A feedback resistor connects the non-inverting input to the output, Reducing noise |
| Power Station and Substation | IEC TS 61000-6-5 | Ideal for signal inversion or phase-shifting tasks |
| Voltage Follower Capability | Cannot act directly as a voltage follower | Easily configured as a voltage follower |
| Phase Shift | Introduces a 180-degree phase shift, which may be undesirable | Provides 0-degree phase shift, not useful for phase inversion needs |
| Applications | Suitable for inverting amplifiers, converters, and differential amplifiers | Ideal for voltage followers, non-inverting amplifiers, and buffer amplifiers |
Inverting Op-Amp Applications
- Audio Amplification: Used in sound systems, radios, and other audio equipment.
- Instrument Amplification: Utilized in test and measurement equipment.
- Automatic control: for systems controlling temperature, humidity, etc.
- Data Communication: Mainly for amplifying and processing digital signals.
- Sensor Signal Amplification: Amplifying ambiguous signals from sensors.
- Signal Filtering: Filtering input signals based on feedback resistance.
NonInverting Op-Amp Application
- Amplifiers: Used in audio and signal amplification circuits.
- Active filters: Designing low-pass, high-pass, and band-pass filters.
- Summing Amplifier: Adding multiple input signals to provide a single output.
- Integrators and Differentiators: Performing various mathematical operations.
- Analog to Digital Converters: Converting analog to digital signals.
- Power Amplifiers: Driving speakers and high-power devices.
- Oscillator: Producing continuous signals.
- Voltage Follower (Buffer): Preventing signal loss in multi-stage circuits.
Popular FAQs Related Inverting & Non-Inverting Op-Amps:
Q1. What Is The Difference Between Inverting And Non-Inverting Amplifiers?
An inverting amplifier inverts the input signal and amplifies it. A non-inverting amplifier amplifies the input signal without flipping it.
Q2. What Is The Input Impedance Of An Inverting Amplifier?
The input impedance of an inverting amplifier is equal to the value of the input resistor.
Q3. What Is The Input Impedance Of A Non-Inverting Amplifier?
A non-inverting amplifier has a very high input impedance, typically in the millions of ohms, meaning it draws very little current from the source.
Q4. What Is The Output Impedance Of An Inverting Amplifier?
An inverting amplifier has a very low output impedance, usually only a few ohms, which helps pass the signal efficiently to the next stage.
Q5. What Is The Output Impedance Of A Non-Inverting Amplifier?
A non-inverting amplifier also has a very low output impedance, similar to an inverting amplifier.
Q6. What Type Of Amplifier Is Most Common In Audio Amplifiers?
Non-inverting amplifiers are more common in audio systems because they preserve the original phase of the signal and only amplify it.
Q7. How Does Feedback Work In An Inverting Amplifier?
In an inverting amplifier, part of the output signal is fed back to the input but flipped 180 degrees. This feedback helps control the gain and keeps the amplifier stable.
Q8. What Does A Feedback Resistor Do In A Non-Inverting Amplifier?
In a non-inverting amplifier, the feedback resistor, along with the input resistor, sets the gain. It feeds a portion of the output signal back to the input to stabilize the gain.
