| 摘要 |
PURPOSE:To attain highly accurate pulse width modulation with short frequency by actuating a shift register by a clock faster several times the operation clock of a counter, inputting data whose pulse width is modulated by the counter to the shift register and changing the extracting position of an output from the short register. CONSTITUTION:When a load signal, the inverse of LD is outputted from a counter 4, data D9-D2 are loaded to counters 1, 2 a ripple carry output, the inverse of RC of the counter 2 is turned to the high level, the counters 1, 2 start to count down, and when the values of the counters 1, 2 reach '0', the ripple carry output, the inverse of RC is turned to the low level and the counters 1, 2 stop their operation. When the ripple carry output, the inverse of RC is turned to the low level, the output is inputted to the shift register 6 and signals with the pulse width of once, twice and three times the period of a clock CP2 are respectively outputted from output terminals QA-QC. These outputs are inputted to a data selector 7 and selected by data D1, D2 and a signal with a required pulse width is outputted from an output terminal Y.
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