What Is a Class D Amplifier?
A Class-D amplifier is an electronic device that uses a transistor's switching mode in order to monitor the power flow. You can use a Class-D amplifier where high outputs are required. A Class-D amplifier contains a high efficiency of 100 percent. The Pulse Width Modulation (PWM) amplifier's high efficiency helps you to reduce power consumption during the usage of an output. The aluminum extrusions on a high-powered amplifier reduce heatsink. Your amplifier's electronics are maintained at a cool temperature. Read on for more information on a Class-D amplifier.
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Uses of Class-D Amplifier
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A Class-D amplifier is used in theaters and auditoriums that need reinforced sound systems. Class-D is used in the Crest Audio CD3000. This Class-D power amplifier contains 1500 watts per channel. You can also use Class-D in bass amplifiers. The Yamaha BBT500H is a bass amplifier that contains 500 watts.
Modulation
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A Class D amplifier uses Pulse Width Modulation (PWM). The input signal converts to a series of pulses. The pulses contain very high frequencies. Your Class D amplifier's switching output is made of a number of pulses. A filter removes unwanted frequencies from the output. The filter maintains efficiency through inductors and capacitors.
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Functions
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Your Class-D amplifier operates by switching outputs in the middle of "on" and "off." When "on" occurs, current flows through the amplifier. Power dissipation is zero. When "off" occurs, voltage acts as an open-circuit, and stops the current flow. PWM is used in Class-D where a wave with a fixed frequency is created.
Topologies
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A Class-D amplifier has two topologies, half-bridge and full-bridge. With a half-bridge topology, two output devices are used. A full-bridge topology uses four output devices. Half-bridge is more flexible. Full bridge is more complicated than a half-bridge. You must use output devices that contain less voltage.
Gate Driver
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The gate driver in a Class-D amplifier provides a high current of 20 to 50ns times in order to charge and discharge throughout the switching interval. In an N-channel half bridge, a voltage is present in between a MOSFET's gate to drive a MOSFET on. If the lower MOSFET's source is connected to Vss, its drive circuit must be referred to the Vss node. You will find that the upper MOSFET is difficult to drive. The upper MOSFET's source is floating in the middle of +Vdd and -Vss.
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