What is a Chopper Amplifier?

A chopper amplifier is a system that transforms signals coming through direct current systems into alternating currents in order to efficiently boost the signal gain. While it is possible to boost the gain on a direct current system, these modifications often increase signal noise and decrease the stability of the signal. The most likely place to come across a chopper amplifier is in high-end electronic signal equipment and heavy machinery that rely on precisely-timed movements. Chopper circuits, the parts that turn a standard amplifier into a chopper amplifier, are also found in a number of other devices.

Chopper circuits are a method of interrupting a signal without destroying it; in essence, they chop up the signal. In most cases, people manipulate the chopped up signal to transform it into something it wasn’t before. Transformation is generally only possible on signals with a distinct beginning and endpoint, which is why the signal is broken up.

The term "chopper circuit" was a catch-all name for a wide range of switches and circuits. The name was applied to any circuit that assisted in the transferal of one signal to another, regardless of reasoning or method. As a result, the term fell out of favor for engineering purposes, as it was simply too vague. One of the only instances where chopper is still used in its original form is chopper amplifier.

In the case of a chopper amplifier, the inputted direct current signal is transformed into an alternating current one. The alternating signal is easier to manipulate and amplify without creating distortion. When a direct current signal is amplified, the weaker the signal, the greater the noise introduced during amplification. If the signal is weak enough, the noise will destabilize it entirely.

It is possible to find these types of amplifiers in a wide range of devices. Many sophisticated electronic measuring devices use a chopper amplifier. These devices read extremely weak signals from their surroundings, chop them up and display the output on a user screen. The signals measured could be nearly anything from sound and vibration to environmental factors.

One of the more common locations in which to find a chopper amplifier is inside a hall probe. These probes measure changes in magnetic fields and rotation speeds. It is possible to find variations of hall probes in many types of internal combustion engines, automobile gearing systems and industrial equipment. These devices measure the signals coming in from the surrounding machinery and transform those signals into user data related to speed, rotation and power output.