High-Efficiency Headphones Amplifier
Designed for EE410 (Linear Electronics)
- Devin Ott (team leader)
- Kevin Cheng
- Xiangyu Dong
- Greg Abrami
WINNER of the EE410
Design Competition at Penn State
Received the following awards:
· Most Energy Efficient Headphones Amp (EE410, Spring2009)
· Lowest Harmonic Distortion (EE410, Spring2009)
Summary (based on the abstract)
The purpose of this project was to design a stereo headphones amplifier to meet a given set of specifications. The project was launched in the form of an EE 410 design competition with the overriding goal of minimizing power consumption while meeting all of the specifications. This report documents the circuit design and analysis performed by the team that produced the most efficient headphones amplifier. Our winning design features a near- rail-to-rail output stage driven by a voltage amplifier with slightly higher supply rails. The amplifiers are biased in the class B region and fundamentally configured to operate from a single supply. The complete application is powered by two AAA alkaline batteries and employs three dc-dc switching converters to produce the necessary voltages to deliver 100mW audio power per channel to each 32Ω load. The final measured efficiency at max output power was 54%, with 23% of power being dissipated in the class B amplifiers, and the remaining 23% being lost in the dc-dc converter circuitry (dominated by the 5.2Vdc output stage supply).
NOTE: Single chip solutions (commercial headphones amp ICs) were not permitted. A class D solution would achieve highest efficiency, but is only practical as a single chip solution (not permitted).
The chief goal of this competition was to achieve the highest energy efficiency in the class, so my team sacrificed in the area of cost and circuit complexity in order to maximize efficiency.
FINAL PROTOTYPE: by Devin Ott
*click image to view full size
STEREO AMPLIFIER CIRCUIT:
DC-DC CONVERTER CIRCUITS:
Prototypes of Early Designs: by Devin Ott
*click images to view full size
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