We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Electronics

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What Is a Voltage-Controlled Amplifier?

By B. Leslie Baird
Updated: May 16, 2024
Views: 9,160
References
Share

In a voltage-controlled amplifier (VCA), the gain is controlled by the voltage level of the signal. The gain is a ratio measurement of the output amplitude divided by the input amplitude. This indicates how much a signal, or sound, has been strengthened. These amplifier systems can be used for music and in public address (PA) or conference systems.

Sound systems are often used in mixing consoles for the recording and playback of music. Consoles use multiple channels to control different features of instruments and vocal sections. Each channel can have its own voltage-controlled amplifier circuit, allowing sections to be mixed and faded separately. The circuit establishes the volume level of a note and quiets the output when the note ends. A master control can allow sections of the music to become louder or softer without interfering with the total mix.

Variable-gain is another term that may be used to refer to a voltage-controlled amplifier. The circuits normally have a gain ratio of one, but the gain can be varied. A gain of one means that the circuit attenuates instead of simply amplifying. Attenuation filters the sounds and can remove unwanted noise while preserving the required tones.

Electronic components found in these systems include operational amplifiers (op amps), junction field-effect transistors (JFETs), and voltage-controlled resistors (VCRs). Voltage-controlled resistors, or varistors, decrease in resistance as voltage increases. A very simple version of a linear voltage-controlled amplifier can be created with two JFETs and one op amp. In this circuit, the JFETs will work as resisters for linear control.

A voltage-controlled amplifier can be classified as two-quadrant or four-quadrant. In a two-quadrant version, if the controlling voltage drops to zero or less, the amplifier will have no output. Using a four-quadrant amplifier, when the voltage reaches zero, the output gain rises, but this output is inverted in its phase. Four-quadrant systems are used for amplitude modulation. Amplitude modulation (AM) varies the strength of a signal, while frequency modulation (FM) varies its frequency.

Amplifiers are available in a wide assortment of dynamic and gain ranges. They offer a great deal of range control with low and low distortion. A voltage-controlled amplifier tends to have a longer life span due to less electronic-part problems than other types.

Share
EasyTechJunkie is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Link to Sources
Discussion Comments
Share
https://www.easytechjunkie.com/what-is-a-voltage-controlled-amplifier.htm
Copy this link
EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.

EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.