# Band-Limited Op-Amp

Model band-limited operational amplifier

## Library

Integrated Circuits

## Description

The Band-Limited Op-Amp block models a band-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.

• s is the Laplace operator.

• f is the 3-dB bandwidth.

The input current is:

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

where Rin is the input resistance.

The block does not use the initial condition you specify using the Initial output voltage, V0 parameter if you select the Start simulation from steady state check box in the Simscape™ Solver Configuration block.

## 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 the output current. The default value is 100 Ω.

Minimum output, Vmin

The lower limit on the operational amplifier no-load output voltage. The default value is -15 V.

Maximum output, Vmax

The upper limit on the operational amplifier no-load output voltage. The default value is 15 V.

Maximum slew rate, Vdot

The maximum positive or negative rate of change of output voltage magnitude. The default value is 1000 V/s.

Bandwidth, f

The open-loop bandwidth, that is, the frequency at which the gain drops by 3 dB compared to the low-frequency gain, A. The default value is 1e+05 Hz.

Initial output voltage, V0

The output voltage at the start of the simulation when the output current is zero. The default value is 0 V.

 Note:   This parameter value does not account for the voltage drop across the output resistor.

## Ports

The block has the following ports:

+

Positive electrical voltage

-

Negative electrical voltage

OUT

Output voltage