Design of a high-efficiency Class D amplifier for ceramic speakers

• Main Author: Hu, Hui.
• Other Authors: Chang Joseph Sylvester
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Electronic circuits
• Online Access: http://hdl.handle.net/10356/53353
• Institution: Nanyang Technological University

This report documents the motivation, methodology and results analysis of design a Class D amplifier for ceramic speakers. In this final year project, both dynamic speaker and ceramic speaker’s properties were examined and analyzed, and a Class D amplifier was designed as an audio amplifier. It was reviewed that ceramic speaker is more than 60 % smaller in size and more acoustical efficient at frequency spectrum from 1 kHz to 8 kHz, but requires a higher supply voltage which is around 15 Vp-p, while dynamic speakers need only around 2-5 Vp-p. Hence ceramic speaker is the future trend in sound producing device. Three dynamic speakers were chosen, and both single tone sinusoidal signal and real life signal were applied on them in analyzing frequency response of sound pressure level, power consumption and efficiency. Last, a Class D audio amplifier was designed and the simulation results were analyzed. Two different carrier signals were used in the simulation, 500 kHz and 10 MHz triangular waves. In general, the Class D amplifier has efficiency lower than 50% at modulation index smaller than 0.1, but the efficiency quickly reaches close to maximum efficiency when the index modulation increases beyond 0.1. The maximum efficiency in can be achieved above 95% for both carriers. The results from both speakers’ analysis and Class D amplifier simulation give the design consideration of Class D amplifier as an audio amplifier, which needs to optimized between speakers’ acoustical efficiency in frequency domain and amplifier’s efficient related to modulation index.