A 0.01%THD, 70dB PSRR Single Ended Class D using variable hysteresis control for headphone amplifiers

Switching audio amplifiers are widely used in H-bridge topology thanks to their high efficiency; however low audio performances in single ended power stage topology is a strong weakness leading to not be used for headset applications. This paper explains the importance of efficient error correction in single ended class-D audio amplifier. A hysteresis control for class-D amplifier with a variable window is also presented. The analyses are verified by simulations and measurements. The proposed solution was fabricated in 0.13 mum CMOS technology with an active area of 0.2 mm². It could be used in single ended output configuration fully compatible with common headset connectors. The proposed class-D amplifier achieves a harmonic distortion of 0.01% and a power supply rejection of 70 dB with a quite low static current consumption.