A 40 nm Fully Integrated 82 mW Stereo Headphone Module for Mobile Applications

An 82 mW fully integrated stereo ground-referenced headphone module is designed in 40 nm CMOS. Lower platform cost is enabled by integrating the headphone module on the same SoC as the baseband functions. Maintaining device reliability with direct battery hook-up and providing large output swing are major challenges for this work, and several techniques were employed to guarantee safe operation for all of the devices under various conditions. Area reduction techniques were utilized to reduce the die cost and achieve lower platform cost. The module supports direct battery hookup with a battery range from 3.1 to 4.5 V and achieves a minimum low frequency, i.e., 217 Hz, PSRR of 110 dB at the lowest battery voltage. Audio quality is preserved by achieving a dynamic range of 100 dB, THD+N of -84 dB at 10 mW output power, and 160 μV pop-and-click noise level during power-up and power-down. The module occupies an area of 0.675 mm ² on the SoC.