A calculator for computing the gain and output voltage of an operational amplifier

(Vout / V1)
(Vout / V2)


This calculator helps calculate the values of the output voltage and the inverting and non-inverting gains of an operational amplifier. Provide the values of the bias resistors, the input voltages, and the supply voltages and press the "calculate" button.

An Operational Amplifier (Op-Amp) is a voltage amplifier with a differential input and a single-ended output. There are two common Op-Amp modes: inverting and non-inverting. The terms "inverting" and "non-inverting" refers to the polarity of the output voltage in reference to the input voltage. An inverting amplifier provides an output voltage that has an opposite polarity to that of the input voltage. The non-inverting amplifier does not invert the polarity of its input voltage.

Note that this calculator solves both inverting and non-inverting op-amp configuration. For a traditional, non-inverting op-amp, set V1 to 0V and use V2 as the input. If and inverting op-amp is desired, set V2 to 0v and use V1 as the input.  Use a very large value for R3 (e.g. 9999999999) if it isn't used. 


For inverting op-amp:

$$A = -\frac{R_{2}}{R_{1}}$$


For non-inverting op-amp:

$$A = 1 + \frac{R_{2}}{R_{1}}$$


$$V_{out1}= A V_{1}$$


With schematics, it is much more convenient to use Op-Amps as circuit blocks rather than specifying individual elements such as transistors and resistors. This is true whether the amplifier is used in discrete or analog circuits. Designing circuits with Op-Amps follows the same methods as other electronic circuits. The first step is often to draw a specification, including what the op-amp circuit is required to do. For example, the gain is specified, the operating temperature is given, or the input impedance is required to be within a specific range. After all the specifications are listed, a basic circuit is then designed. Most engineers nowadays use circuit modeling software to design the op-amp circuit, a prototype is then built and tested so that changes can be made to meet or improve the specification, alter functionality, or reduce the cost.

Further Reading

Textbook - Introduction to Operational Amplifiers

Textbook - Inverting and Non-inverting Operational Amplifiers

Video Lecture - Op-amp Characteristics