| 摘要 |
PURPOSE:To decrease the numbers of series resistances and comparators in use by connecting a series resistance network between reference power sources and outputting the potential across an optional resistance, and providing an analog-digital (A/D) converter which uses said output as a new reference power source. CONSTITUTION:The reference power source of the A/D converter 6 has a potential as high as the potential across one of resistance of the series resistance network 3. For the purpose, the level of a signal to be sampled next is forecasted by using a digital output 4 and a switch 8 is switched to put the forecasting range within an input range. The level of an analog signal is divided by (n) into input levels 10-1-10-n. At this time, when the analog input signal 1 is sampled in a range of an input level 10-i (i=1-n), the reference potential of the A/D converter 6 at next time has potentials 9-i1 and 9-i2. Thus, the sampling frequency is set relatively higher than the maximum frequency of the analog input signal and then components of the A/D converter are reduced.
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