| 摘要 |
PROBLEM TO BE SOLVED: To provide a pulse waveform forming circuit, with which possibility to affect a pulse to be outputted is low even when a noises or the like are superimposed on an input signal. SOLUTION: The pulse waveform forming circuit 20 outputs periodical rectangular waves when a cycle signal is inputted. In this pulse waveform forming circuit 20, when the signal of a voltage lower than first and second threshold voltages is inputted, a first voltage is outputted and when the signal of a voltage higher than the first and second threshold voltages is inputted, a second voltage is outputted. When a voltage between the first and second voltages is inputted, the output is turned into high impedance state. Further, in such a pulse waveform forming circuit 20, cycle signals are inputted to a first inverter 22 having the first threshold voltage and a second inverter 24 having the second threshold voltage. Moreover, this pulse waveform forming circuit 20 is provided with an output circuit, with which two PMOS transistors 31 and 32 and two NMOS transistors 33 and 34 are serially connected.
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