5 levels filter-free class D audio power amplifier for portable applications

Abstract

An integrated novel Filter-Free Class D Audio Power Amplifier suitable for mobile applications is designed with Hynix 0.35um CMOS Process. This Amplifier has 6dB feedback gain and 5 level differential output which enhances the linearity of audible signal. To make 5 level output, the proposed circuit has total 6 switches and 1 external capacitor that adds one more level. To reduce the number of triangle wave generator, new PWM modulator is designed. For eliminating the necessity of additional circuit to charge external capacitor, new switch control method is proposed. The performance of proposed circuit is evaluated by simulation and its results show that its maximum power driving 8Ω speaker load is 560mW when supply voltage is 3.3V and Maximum Power Efficiency of over 92.5% is achieved at full power.