| 摘要 |
PURPOSE:To attain the demodulation of a data with high accuracy by using a clock whose speed is sufficiently faster than the data speed of a pulse width modulation signal for the oscillation clock of an oscillation circuit. CONSTITUTION:The pulse width modulation signal inputted from an input terminal 1 is inputted to a count circuit 3. The oscillation circuit 4 applies a clock sufficiently faster than the data speed of the pulse width signal to the count circuit 3. The circuit 3 counts up the high level time and the low level time of the inputted pulse width modulation signal respectively and obtains its difference and gives an output to a holding circuit 5 at the next leading of the next high level of the pulse width modulation signal. Then the output of the holding circuit 5 is inputted to an amplitude converting circuit 6, where the signal is converted into the amplitude proportional to the output of the holding circuit, inputted to an envelope detection filter circuit 7, and the envelope detection is applied to obtain the demodulation data of the inputted pulse width modulation signal.
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