| 摘要 |
A novel type of digital-to-analog converter circuit is disclosed for an electronic timepiece having a speech synthesizing capability. The converter circuit utilizes pulse width modulation to form a train of pulses in response to successive digital signals which specify amplitude and polarity values for synthesizing speech, with the pulse widths being determined in accordance with the digital signal values. By filtering out the unwanted high frequency components of this pulse train, speech signals can be synthesized through an audio transducer. Such a digital-to-analog converter is capable of operating in a satisfactory manner at low levels of supply voltage, and has a very low power consumption. |
