# Finite-Gain Op-Amp

Model gain-limited operational amplifier

## Library

Integrated Circuits

## Description

The Finite-Gain Op-Amp block models a gain-limited operational amplifier. If the voltages at the positive and negative ports are Vp and Vm, respectively, the output voltage is:

where:

• A is the gain.

• Rout is the output resistance.

• Iout is the output current.

The input current is:

`$\frac{{V}_{p}-{V}_{m}}{{R}_{in}}$`

where Rin is the input resistance.

The output voltage is limited by the minimum and maximum output values you specify in the block dialog box.

## Dialog Box and Parameters

Gain, A

The open-loop gain of the operational amplifier. The default value is `1000`.

Input resistance, Rin

The resistance at the input of the operational amplifier that the block uses to calculate the input current. The default value is `1e+06` Ω.

Output resistance, Rout

The resistance at the output of the operational amplifier that the block uses to calculate the drop in output voltage due to output current. The default value is `100` Ω.

Minimum output, Vmin

The lower limit on the operational amplifier output voltage. The default value is `-15` V.

Maximum output, Vmax

The upper limit on the operational amplifier output voltage. The default value is `15` V.

## Ports

The block has the following ports:

`+`

Positive electrical voltage

`-`

Negative electrical voltage

`OUT`

Output voltage