Class D amplifier


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class D amplifier

[‚klas ′dē ′am·plə‚fī·ər]
(electronics)
A power amplifier that employs a pair of transistors that are connected in push-pull and driven to act as a switch, and a series-tuned output filter, which allows only the fundamental-frequency component of the resultant square wave to reach the load.

Class D amplifier

An audio amplifier that works in the digital domain. It generates the equivalent analog output for the speakers by using pulse width modulation (PWM) or pulse density modulation (PDM) rather than the traditional digital-to-analog conversion. See PWM and PDM.

Less Heat than Analog
Because pulse modulation output signals are either on or off, Class D amplifiers produce far less heat than analog amplifiers. Reaching efficiencies greater than 90% compared to only 50% for analog, they are widely used for every amplification requirement from cellphone speakers to high-end stereos.

Digital and Analog
Class D was not coined for "digital;" it was the next letter after Class C. However, it does produce a "digital-like" output because the signals are generated by turning a switch fully on or off. But it is not technically digital because the output is not digital data. It is a modulated audio signal that is feeding analog speakers and is equivalent to the output of a traditional analog amplifier. Some call this a "synthesized analog" output. See amplifier classes.
References in periodicals archive ?
Global Audio Class D Amplifier Market Report 2019 - Market Size, Share, Price, Trend and Forecast is a professional and in-depth study on the current state of the global Audio Class D Amplifier industry.
Class D amplifiers operate on a principle called pulse width modulation.
Unlike a linear amplifier, which uses transistors to increase the amplitude of an applied signal, Class D amplifiers use transistors as ON/OFF switches.
Each of these elements can be achieved with Class D amplifiers designed to manage and suppress EMI in consumer audio systems, as shown in Figure 1.
Whatever spurious signals are carried by the power supply to a Class D amplifier can find their way to the output signal.
The text is divided into six parts: the basics, advanced design techniques, real-world design considerations, simulation and measurement, topics in design, and class D amplifiers.