A 2.5W tablet speaker delivering 3.2W pseudo high power by psychoacoustic model based adaptive power management system

Abstract

For a 2.5W speaker in tablets, the proposed adaptive power management (APM) system can deliver a pseudo high power of 3.2W with a ±4V supply because it suppresses 0.7W power on tones that may damage a 2.5W speaker and escape the notice of human ears. With z-domain digital signal processing (z-DSP) and psychoacoustic model, high efficient power management and high sound quality can be achieved simultaneously. Conventional automatic gain control (AGC) only has the ability of 0.32W power suppression. Moreover, suppressing power by conventional clipping technique increases total-harmonic-distortion (THD). In contrast, the proposed real-time dynamic loading impedance (RT-DLI) monitoring brings forward a way to solve the problem on speaker damage while keeping low THD during high sound pressure level (SPL). THD in the APM system is slightly higher than that of original sound 1.1dB, comparing to the disadvantage of 8.6dB increasing caused by conventional clipping technique.