INTERMEDIATE POTENTIAL DETECTOR

PURPOSE:To prevent a noise from appearing on an output signal even when a noise is superposed to an input signal. CONSTITUTION:When the noise is superposed on the input signal a1, the noise appears in a manner of being amplified on the output signals of (c) to (e) of inverters 11 to 13 with different switching levels. But concerning flip-flops 15 and 17, when data is set once, output data does not change even if additional clock is inputted as long as input data do not change. The input data are connected to a power supply to be invariable. Namely, the noise amplified by the inverters 11 to 13 is cut by the flip-flops 15 and 17. Consequently, the noise is cut off in the output signals (h) and (i) of the flip-flops 15 and 17 and the noise does not appear on a signal output terminal 21. Thus, a circuit malfunction which is conventionally caused by the noise is prevented.