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

bluesnarfing unauthorised access to data on bluetooth enabled devices Tim Bonnett | Alpha Micro Components
How to Cost Effectively Protect Industrial Equipment from Wireless Hacking
With more systems being controlled wirelessly and over the Internet of Things, security is a key issue. A number of techniques are being used by attackers, but are the security experts ahead of the game. Find out about some solutions.
Online - Transmission Lines, S-Parameters & Smith Chart
Understand these essential concepts without complex mathematics

More training courses

R&S Higher Order MIMO Testing
Rohde & Schwarz presents this authoritative whitepaper on higher order MIMO testing.

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