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 ?
s (Nasdaq:CRUS) new CS4525 is an innovative, highly integrated single-chip Class D Amplifier for the rapidly expanding global flat-panel digital television market.
Freescale's Class D amplifier with its advanced digital feedback is a real breakthrough and allows OEMs to achieve the highest quality performance, in a smaller form factor and still benefit from the power savings of a Class D amplifier design.
Other Class D amplifiers can improve efficiency, but at higher cost, greater complexity and lower audio quality," explained Larry Kirn, JAM CTO.
Wolfson believes that low cost high efficiency Class D amplifiers are about to have a major impact on the design of domestic, portable and in-car audio and ease of design and support will be key to ensuring short times to market for new products using this exciting technology.
Tuner compatibility within the new Philips DVD receivers is achieved with the Class D amplifier from Philips' semiconductor division," said Peter Straker, function manager for power amplifiers in BCU Audio at Philips Consumer Electronics.
A typical DDX amplifier will be 20% more efficient than a comparable class D amplifier and 300% more efficient that a class AB design.
Conventional Class D amplifiers have been around for 60 years in theory and about 30 years in practice," explains Gary Suttle, president and chief executive officer, Rockford Corporation.