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在传统D类音频功放的半桥输出上再级联一级半桥,构成一种新型二级联半桥D类音频功放。两半桥采用载波相移调制法,即两个相位相反的三角载波调制同一个音频波。对传统D类音频功放和新型D类音频功放输出的PWM波进行傅里叶展开分析,得到谐波数学表达式,并利用贝塞尔函数求解出各次谐波的幅度。理论分析和实验结果表明,基于载波相移的新型功放达到了等效增频载波的目的,增加了输出电平数,降低了开关器件工作频率和耐压的要求,也降低了输出谐波幅度和电磁辐射干扰。
The traditional half-bridge output of the D-type audio amplifier is cascaded again to form a new type of cascaded half-bridge Class-D audio amplifier. Two halves of the bridge carrier phase shift modulation, the two opposite phase triangular carrier modulation with the same audio wave. The traditional D-class audio amplifier and the new D-type audio amplifier output PWM wave Fourier analysis, harmonic mathematical expression, and the use of Bessel function to solve the magnitude of each harmonic. Theoretical analysis and experimental results show that the new power amplifier based on carrier phase shift achieves the equivalent of carrier frequency increase, increases the number of output levels, reduces the operating frequency and withstand voltage of switching devices, and reduces the output harmonic amplitude And electromagnetic interference.