International Journal of Open Scientific Research IJOSR Vol.2, No. 2, 1-9 ©KINDI PUBLICATIONS March, 2014 www.kindipublication.com ISSN: 2336-0046 1 Design a New Architecture of Audio Amplifier Class-D for Cellular Phones Karim EL KHADIRI and Hassan QJIDAA Sidi Mouhamed Ben Abbellah University Faculty of Science Dhar El Mahrez Laboratoire d’Electronique Signaux – Systèmes et Informatique (LESSI) Fez, Morocco Abstract This paper presents a new architecture of class D audio amplifier with 0.4 W output power and 95% efficiency with an 8 ohm load. This class D uses a pulse width modulation scheme that eliminates the output filter. It operates with a 2.4 V to 5V supply voltage. The fully differential class-D audio amplifier is implemented with a TSMC 0.13-um 2P4M CMOS process, and the chip area is 325 x 300 um2. It has a THD as low as 0.04%, with a flatband response between 20 Hz and 20 kHz. Keywords: Class-D Amplifier, H-Bridge, Triangle-wave generator, Pulse-width-modulation. CORRESPONDING AUTHOR: karim.elkhadiri@usmba.ac.ma, +212676548780 I. INTRODUCTION High power efficiency, small size and reduced heat dissipation are highly desirable in battery- powered mobile systems and switched-mode class-D amplifiers can readily satisfy these requirements. However, full adoption of class-D technology in mobile systems has been somewhat limited due to concerns such as signal distortion and noise, poor power supply noise rejection, electromagnetic interference (EMI) and the requirement for external LC filters. The operation of class D amplifier was invented in 1959 by Baxandall, who suggested using LC oscillator. The motivating factor research in class D amplifier is efficiency. The efficiency of linear amplifier is 30–40% practically in spite of 78.5% theoretically. At the same time, it must increase the chip area or even add a plus radiating flange for the elimination of heat; thus too much area is taken and also the cost is unaffordable. When it comes to class D amplifier, since the output power metal– oxide semiconductor field effect transistors (MOSFETs) of class D amplifier operate in the triode and cut-off regions, the efficiency of class D is over 80% in practical application with 100% theoretic efficiency, which can greatly reduce the power dissipation, area of chip and printed circuit board (PCB) and cost. Therefore, class D amplifiers are becoming favourable in consumer electronic products such as DVD, LCD-TV, MP4 and cell phone[1], [2], [3], [4], [5][6], The modulation techniques commonly applied for the realization of analog class D amplifiers include: (1) pulse-width-modulation (PWM) and (2) sigma–delta (∑D) modulation. Digital class D