Non-Inverting Operational Amplifier Basics

Operational amplifiers (Op-Amps) are an important component in many electronic circuits found in everyday life. A giving an understanding of the working principles behind them is an essential knowledge for electrical engineers. Non-inverting Op-Amps are a type of these components which can be used in a range of circuits.

Operation and Components of a Non-Inverting Operational Amplifier

A Non-inverting Op-Amp has two inputs, a negative input (inverting input) and a positive input (non-inverting input). It also contains a single output. The non-inverting input is not actively used in the operation, but the inverting input is used as the reference. The output signal of the op-amp is inverted with respect to the reference obtained from the inverting input. Non-inverting Op-Amps are designed to have large gain which is determined by the ratio of two resistors, Rf (feedback resistor) and R in (input resistor). The gain is given by the formula:

Gain (A) = 1 + (Rf/Rin)
Furthermore, Rf and Rin determine the input impedance and output impedance of the operational amplifier.

Applications of a Non-Inverting Operational Amplifier

Non-inverting Op-Amps are used in multiple applications such as signal conditioning, signal amplification, signal filtering, and voltage amplification. They can also be used in combination with other op-amps to create a range of circuits, including differentiating circuits and active filters.

Some of the most important applications of a non-inverting op-amp are listed below: 

• Voltage multiplication: Non-inverting op-amps can be used to increase or decrease the voltage of a signal.
• Voltage buffering: May be used in voltage buffering applications to provide a low output impedance.
• Instrumentation amplifiers: Non-inverting op-amps are a key component in instrumentation amplifiers which are used to amplify weak signals from transducers.
• Audio amplifiers: Non-inverting op-amps are used in audio amplifying circuits.

Conclusion

Non-inverting op-amps are used in a wide range of applications. With the understanding of the operation and components of a non-inverting op-amp, one will be able to design efficient circuits using this type of op-amp. An operational amplifier (or “op amp”) is an active circuit element that is commonly used in electronics circuits for a variety of purposes. One of the most basic, yet important, uses of an op amp is as a non-inverting amplifier, a circuit where the output signal has an amplitude that is the same as the input, but with an inverted phase (i.e., 180 degrees out of phase). Non-inverting amplifiers are essentially voltage followers that amplify the input voltage, allowing them to be used in applications such as variable gain amplifiers, precision current sources, oscillators, filters, and so on.

The basic design of a non-inverting amplifier is based on a three-stage amplifier configuration, with the input signal applied to the non-inverting (+) input of the op amp, and the output taken from the op amp’s output terminal. The feedback network between the non-inverting input and the output is usually implemented as a voltage divider, with one input of the divider connected to the output terminal and the other input connected to ground. This feedback loop creates a negative feedback – where the output voltage is of the same polarity as the input voltage – which is used to buffer the input signal so that the output voltage is only slightly different than the input amplitude.


The gain of a non-inverting amplifier is determined by the ratio of the resistance in the feedback network, which is usually denoted as Rf, to the resistance of the input voltage divider, denoted as Rin. The gain of the amplifier is determined by the following formula:

A = 1 + Rf/Rin) 

The input impedance (or “load”) of the op amp is determined by the ratio of the resistance of the input voltage divider, Rin, to the resistance of the output impedance of the op amp, denoted as Rop. The input impedance is determined by the following formula:

Zin = (Rin/(Rin + Rop))

The output impedance, or the resistance of the output terminal of the op amp, is determined by the ratio of the resistance of the feedback network, Rf, to the output impedance of the op amp, Rop. The output impedance of the amplifier is given by the following formula:

Zout = (Rf/(Rf + Rop))

Overall, the non-inverting amplifier is an incredibly useful and versatile circuit configuration, with a wide range of applications in electronics circuits. From audio amplifiers to signal processing amplifiers, voltage followers, to current sources and more – this simple three-stage amplifier circuit can be found in almost any electronic circuit.