The 29th AES Conference, "Audio for Mobile and Handheld Devices", all digital, September 2 to 4, 2006 Seoul National, lUniversity Campus
Digital Audio Presentations - Part 3
Full Digital Amplification for Handheld Devices
John Oh, Pulsus Technolgies, Korea
The Class-D audio amplifier has intrinsic advantage of power- efficiency in digital mobile and handheld application such as mobile phones and MP3 players. The digital class-D amplifier (in other words, full digital amplifier) is ideal as we can implement a better quality audio with integrated DSP feature, while digital interface is immune to noisy environment of handheld systems such as mobile phone. However, this technology was could not be adopted in handheld audio systems because of several technological challenges. We will review the issues of full digital amplification in handheld environment and implementation of SoC products which was first applied to music mobile phone recently.
Chaotic Modulation in PWM Digital Amplifier
Vladislav Shimanskiy, Samsung Electronics, Korea
Performance of a pure digital audio amplifier using pulse width modulation (PWM) highly depends on suppression of high frequency, inaudible, components in its spectrum. Noise-like phase modulation of PWM carrier signal allows reducing of nonlinear effects in demodulation filter, and can be of advantage for EMC reasons. In this paper we propose a method of digital PWM amplifier implementation where a digital chaotic oscillator is used for carrier spreading. Digital Modulation principle, interval modulator schematic, and chaotic oscillator structure as well as experimental results are presented in this paper.