| 摘要 |
PURPOSE:To stably generate a sinusoidal wave by simple circuit constitution by providing a switch group connected to each reference voltage and plural reference voltage generating circuits and connecting other terminals of the switches in common and using the common connecting point via a low-pass filter as a waveform output terminal. CONSTITUTION:Plural reference voltage sources 1 and switch groups 2-4 each one terminal of which is connected to each reference voltage are provided, and the other terminals of the switch groups are connected in common and a low-pass filter including a capacitor 6 is provided to the common terminal to form the waveform output terminal. Control signals (a)-(c) are control signals to switch respectively the switches 2-4 and the switches are turned on when the signals are at a high level. Figure (d) shows a waveform at an output terminal 7 when no capacitor 6 is connected. When the capacitor 6 is connected, the on-resistance of the switch and the capacitor constitutes a low-pass filter and the waveform is unsharpened and a sinusoidal output (e) is outputted to the output terminal 7.
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