| 摘要 |
PURPOSE:To reduce the area of an element, by replacing the function of a required capacitor with a P-N junction capacitance of an MOSFET. CONSTITUTION:When the period of fluctuation of a signal at a terminal 21 is suficiently short to a time constant comprising off-resistance of the MOSFETs 22, 23 and capacitors 27, 28, replaceable by the junction capacitance at the source side, an output terminal 30 of an NOR circuit 29 keeps a level ''1'', and when the period of fluctuation of the signal at the terminal 21 is sufficiently long, since one input of the NOR circuit 29 goes to the level ''1'', the terminal 30 outputs a level ''0''. When a signal to be discriminated which is applied to the terminal 21 is AC, the level ''1'' is outputted to the terminal 30 and when DC, the level ''0'' is outputted. Since the junction capacitance of the MOSFETs is used as the capacitance requested at the input terminal of the logical operating circuit, the element area is reduced. |
