| 摘要 |
The D/A converter (106) operates with a pulse-width modulation circuit (108), in order to generate a pulse train as a function of sequential digital signals which determine the amplitude values and polarity values for the purpose of voice synthesis. The pulse width is determined in this case from the values of the digital signals. By filtering out the undesired radio-frequency components of this pulse train by means of a low-pulse filter (112), the voice signals can be synthesised by an audio converter (28). Such a D/A converter functions perfectly at very low supply voltages, and has a very small power input. <IMAGE> |
