| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a pulse width modulation circuit capable of highly accurate pulse width modulation by raising the resolution of a pulse width without enlarging a circuit scale. <P>SOLUTION: The pulse width modulation circuit is provided with a ring oscillator 1 for outputting dual oscillation signals from the output terminals of differential buffers BF1-BF8, a selector 2 for selecting one of 16 pieces of the oscillation signals of the ring oscillator 1 by low-order 4 bits of digital signals of 8 bits, a counter 3 for outputting a pulse for each maximum value count of the digital signals of high-order 4 bits for the oscillation signals outputted from the differential buffers, a rise detection circuit 8 for detecting the rise of the pulse of the counter 3 and outputting a set pulse, a counter 4 for performing counting corresponding to the digital signals of the high-order 4 bits and outputting pulse output after the selected oscillation signal is outputted, a rise detection circuit 9 for detecting the rise of the pulse output of the counter 4 and outputting a reset pulse, and a flip-flop 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
