Audio amplifier claims higher efficiency than Class D

Audium Semiconductor has launched an audio power amplifier IC which it says is 20 times as efficient as competing devices at normal listening levels (defined as 73 dBC sound pressure level  at a distance of 1 metre with a speaker sensitivity of 89 dBC/W), without compromising audio quality. The AS1001 operates from a nominal 1.5-V power supply and delivers 100 W peak power output. The amplifier is claimed to be so efficient that a battery-powered amplified loudspeaker used three hours per day should run for up to 10 months on a set of four C batteries.

The amplifier also enables the development of smaller, cooler mains-powered audio equipment with fewer heat sinks. Applications include totally wireless speakers, home theatre surround sound speakers, and battery-powered travel speakers. Future Audium ICs will support MP3 docking stations and USB powered speakers.

The AS1001 architecture uses patented techniques to minimise fixed power losses and output-dependant variable power losses. The modulation scheme uses low switching rates to minimise switching losses. Power rail switching enables efficient amplifier operation from a low voltage rail most of the time, with a DC–DC boost converter driving higher voltage transistors on extreme audio peaks.

Targeting battery powered applications; the AS1001 is housed in a single 64QFN package and operates directly from a 0.8–1.8 V supply, which makes it compatible with alkaline primary cells and NiMH secondary cells.