High-power Filter-less Class-d Audio Amplifier Design

With the advent of the Internet of Things and the emergence of various miniaturized electronic devices,sound has received more and more attention as an important platform for information transmission and communication between humans and machines.From home theaters to Bluetooth headphones,audio amplifiers play an indispensable role.Among them,the Class D stands out in many different architecture with its excellent work efficiency.With the continuous development of the technology,the audio quality of Class D amplifier has also been greatly improved.The compatibility with digital circuits is of great significance which helps Class D amplifier occupies the mainstream position of the audio amplifier market.However,there is still a lot of room for improvement in sound quality,work efficiency and costs reduction.This thesis designs a high-power filter-less Class-D audio power amplifier,which has great reference value in practical applications and engineering.The Class D audio amplifier designed in this thesis has a second-order integrator as a compensator to increase the loop gain and enhance the noise suppression of the system,thereby improving the quality of the output audio.The PWM modulation method of BD mode can greatly reduce the current on the speaker load,saving power while also allowing this design to have the characteristics of no filter.The Class D amplifier designed in this thesis can also provide four different gains and five different switching frequencies,all of which can be output at a maximum power output of 100 W,adapting to a variety of needs in different operating environments.The design of the input protection circuit effectively protects the chip from being damaged by an oversized input.This thesis first introduces the background and expectations of Class D amplifiers,and then introduces different types of audio amplifiers and focuses on Class D amplifiers,and then analyzes and compares their parameters and characteristics.The system loop of the chip was then designed,and the feasibility of the design was verified by using SIMULINK simulation,which proved the advantages of the design.Finally,the internal sub-circuits of the chip are designed and simulated,and the overall simulation of the chip is carried out which meets the design requirements among all different process corners.The simulation results of the Class D audio amplifier designed in this thesis indicates that its maximum output power is 100.9W,and the system efficiency at this output power is94.8%,the THD+N with an power supply of 21 V and an output power of 50 W is 0.1%,and its signal-to-noise ratio is 126 dB.