基于采用權電流D/A方式實現合成語音輸出方式有集成電阻離散性大、開關的非線性，以及功耗高等缺點，提出了利用脈沖寬度調制(PWM)技術的方法將數字語音信號直接轉換為脈沖寬度調制波，并通過低通濾波器生成模擬語音信號。PWM語音輸出方式相對一般的DAC語音輸出方式具有功耗小、工藝適應能力強、設計可靠等優點，并且PWM語音輸出方式已經成功應用于語音合成芯片中，輸出合成語音質量良好

For the output mode of speech synthesis which has been come true by using traditional D/A method, there is a lot of disadvantages, such as high discrete integrate resistance, nonlinear switching, high power dissipation. We propose a new method based on the theory of pulse width modulation (PWM), which convert directly the digital speech signal to the pulse width modulation wave and become analog speech signal by passing low-pass filter. Comparing with the traditional D/A method, the new method has the advantages of low power dissipation, high technique adaptability and high designing reliability. It has been applied in the chips of speech synthesis successfully.