| 摘要 |
PURPOSE:To obtain a Schmitt circuit which consists of less elements and has excellent characteristics by a C-MOS process. CONSTITUTION:In a figure, Q1, Q2, and Q3 are P channel MOS.FET elements, and Q4 is an N channel MOS.FET element. When an input level is higher than the earth level, the elements Q1 and Q2 are turned on and the Q3 and Q4 are turned off. When the input level rises above a threshold voltage VTH, a voltage i1.RON=VDS (RON: source-drain resistance value in on state) is developed between the drain and source of the Q2. When it further rises, the voltage VDS exceeds the threshold voltage VTH of the Q3 and a current i2 starts flowing. In this case, the current i1 decreases. Then, the potential at a connection point P2 drops and the channel of the Q3 becomes wider to further increase the current i2, so that the current i1 is further decreased. This positive feedback inverts the level at an output terminal OUT abruptly. If the input level drops below a level VCC, the current i1 starts flowing similarly and the current i2 decreases, inverting the level at the output terminal OUT abruptly through this positive feedback. |
