| 摘要 |
PURPOSE:To eliminate or simplify the output filter, by smoothing the waveform with an interpolation performed among the quantized signals. CONSTITUTION:The output 14 of the D/A converter 18 is input to a subtractor circuit consisting of the resistances 22, 23 and 24 plus an operational amplifier 25 as well as a sample holding circuit consisting of the switch 20 and capacitor 21 to retain a sample holding by the sampling pulse 31 having the same period as the D/A conversion starting pulse. The output 16 of the sample holding is supplied to the subtractor circuit. The output of the subtractor circuit is supplied to the inverse amplifier 30, and the current according to the level of the output 32 of the amplifier 30 is sent to the capacitor 27 via the resistance 28. The switch 26 and the capacitor 27 form a sample holding circuit. Then the voltage of the same waveform as the output 14 of the D/A converter 18 generated at the terminal of the capacitor 27 is delivered as smoothed into the waveform 15 from the step-shaped waveform by the charge (discharge) caused by the above-mentioned current. |
