High-Quality, Low-Cost Audio Achieved with GaN
Jul 29, 2021
Until recently, to achieve high-quality sound from an audio amplifier cost thousands of dollars and relied on a large, heavy, power-hungry class-A amplifier. Now, the advent of gallium nitride FETs and ICs is ushering the age of high quality, lower cost class-D audio amplifiers.
Distortion Performance Issues Lowered with GaN
Historically, meeting the required distortion performance targets (THD+N, TIM and IM) for high-quality audio, class-D amplifiers had to resort to incorporating large amounts of feedback circuitry to compensate for poor open-loop performance. The source of this distortion was the silicon power MOSFET.
Processors for class-D amplifiers create a high-frequency, pulse-width-modulation (PWM) small signal that represents the audio signal. The power transistors, in either a half-bridge or full-bridge configuration, convert the small signal to a large signal to drive the speakers through a filter. Since each pulse is a square wave, increasing frequency gives a better representation of the audio signal. With each switching cycle, power is dissipated through both switching losses and conduction losses, creating a tradeoff between sound quality, operating frequency, and power dissipation.
The objective of the power stage of the class-D amplifier is to create an exact large-signal replication of the small-signal source while dissipating little heat. The significantly higher switching and thermal performance of GaN-based FETs and ICs results in a waveform that is much closer to the desired ideal wave form than a silicon MOSFET can reach.
Premium Audio Class-D Amplifier with GaN Technology Delivers Sound Quality Above Class-A Designs
GaN technology is enabling consumers to enjoy the benefits of class-D above the quality of class-A. A growing number of manufacturers are releasing gallium nitride-based designs. The Mini GaN 5 from Premium Audio Products is a two-channel gallium nitride, balanced audio power amplifier.
The power for this amplifier is 200 W RMS per channel into 8 ohms. The Mini GaN 5 also drives 4 ohm and even 2 ohm speakers. Despite its small size (9 ¾” wide x 7” deep x 1 ¾” high), the sound quality is impressive. The THD+N is about 0.006% and the Gain: Low Gain = 26 dB, Medium Gain =28 db, and High Gain = 32 dB.
EPC eGaN FETs Provide Performance and Reliability
Tom Rost, owner and head designer at Premium Audio, selected EPC’s eGaN® FETs for their GaN-based amplifiers due to the extreme performance capability and reliability that they provide. According to Rost, “EPC’s gallium nitride products allow Premium Audio’s GaN amplfiers to provide a listening experience like no other. And, not only do eGaN FETs deliver incredible performance, but enable the best price performance in audiophile quality amplifiers.”
Gallium nitride FETs and ICs are enabling an age of high quality, low cost class-D audio amplifiers -- delivering higher-quality sound and lower cost than class-A amplifiers. The superior switching performance of GaN FETs and ICs results in near ideal waveforms for lower distortion and higher audio quality than silicon MOSFETs can achieve. This performance is heralding in a new era of high quality, reasonably priced class-D audio amplifiers bringing audiophile quality amplifiers to high volume consumer and automotive applications.