3W无滤波D类音频功率放大器设计

Design of a 3W Filterless Class D Audio Amplifier

设计了一种免滤波的双通道D类音频功率放大器,该功率放大器采用双边对称三角波作为载波的PWM调制方式,有效降低功放的总谐波失真度。测试结果表明:当电源电压为5V、负载为4Ω、输入1kHz的正弦波信号、额定输出功率为3W时,总谐波失真(Total harmonic distortion,THD)为10%,输出功率为1W时总谐波失真+噪声(Total harmonic distortion+Noise,THD+N)仅为0.15%,效率高达85%。电路采用无滤波器结构,可以直接驱动扬声器,具有高效率、低静态电流与较强的抗电源干扰EMI的特点。

A dual-channel filter-free class D audio power amplifier was designed,in which the power amplifier used the bilateral symmetrical triangle wave as the carrier of the PWM modulation method,effectively reducing the total harmonic distortion of the power amplifier.The test results showed that:Driving 4Ωloads under 5Vpower supply,10% harmonic distortion THD could provide 3 Wrated output power.When the output power of 1W,total harmonic distortion plus noise(THD+N)was only 0.15%,and efficiency was up to 85%.Circuit designed by filterless structure could directly drive the speaker with high efficiency,low quiescent current and strong anti-interference characteristics of EMI power supply.