Op-amp variable gain amplifier circuit

- a variable gain circuit using an operational amplifier

Most operational amplifier or op-amp circuits have a fixed level of gain. However it is often useful to be able to vary the gain. This can be done simply by using a potentiometer on the output of a fixed gain op-amp circuit, but sometimes it may be more useful to vary the actual gain of the amplifier circuit itself. This can be achieved very simply by using the variable gain operational amplifier circuit shown below.

The circuit is very simple, and only uses one additional component over that of a basic operational amplifier circuit. The circuit simply uses a single variable gain amplifier. The circuit uses a single operational amplifier, two resistors and a variable resistor. Additionally not only is the gain varied but also the sign.

variable gain operational amplifier circuit

Variable gain operational amplifier circuit

Using this circuit the gain can be calculated from the formula given above. In this the variable "a" represents the percentage of travel of the potentiometer, and it varies between "0" and "1". It is also worth noting that the input impedance is practically independent of the position of the potentiometer, and hence the gain

. . . . .     << Previous     | Next >>


Share this page


Want more like this? Register for our newsletter








Optimising high level operating systems for embedded applications Yannick Chammings | Witekio
Optimising high level operating systems for embedded applications
Yannick Chammings or Witekio looks at improving user experience of many software driven items: one key method applicable to many systems is to reduce the boot time.
Training
Online - Designing GaN Power Amplifier MMICs
Learn how to design high performance GaN power amplifier MMICs

More training courses

Whitepapers
Acquiring an Analog Signal: Bandwidth, Nyquist Sampling Theorem & Aliasing
In this white paper from National Instruments learn all you need to know about analog signal sampling: bandwidth, amplitude error, rise time, sample rate, Nyquist Sampling Theorem, aliasing & resolution.

More whitepapers










Radio-Electronics.com is operated and owned by Adrio Communications Ltd and edited by Ian Poole. All information is © Adrio Communications Ltd and may not be copied except for individual personal use. This includes copying material in whatever form into website pages. While every effort is made to ensure the accuracy of the information on Radio-Electronics.com, no liability is accepted for any consequences of using it. This site uses cookies. By using this site, these terms including the use of cookies are accepted. More explanation can be found in our Privacy Policy