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 ?
Limited Tenders are invited for Supply of proximity switch / isolating switching amplifier
The amplifier - a 56 kVA class D switching amplifier - is forced-air cooled and incorporates an integral DC field power supply which is required for the shaker field coils.
In any switching amplifier, energy is lost each time the amplifier switches its output from one state to another.
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Class T" is Tripath's name for their low distortion, hall range sophisticated variation of Class D switching amplifier technology which is used by Panasonic and quite a few others, mostly in home theater and large screen TVs.
Samples are available of the ZXCD1000 Class D switching amplifier controller IC, which has been designed for quality audio, high efficiency, small size, and low cost per watt.
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In the case of a switching amplifier design output bridge design is critical.