| 摘要 |
PURPOSE:To decrease the logic amplitude of a circuit and at the same time increasing the speed of switching action, by installing a constant voltage device between a power source and a depletion MOSFET. CONSTITUTION:An enhancement mode MOSFETE16 is always in a conduction mode since its gate is connected to a power source VDD. The difference of potential between the power source VDD and the source potential VD1 can be approximated to the threshold voltage VT of an enhancement mode MOSFETE2 by securing a sufficiently large size for a transistor. At the same time, the fluctuation of the potential VD1 caused when the circuit is switched is reduced by a capacity C1 and thus a reduction of working margin due to a fluctuation of the potential VD1 plus an effect to speed can be reduced. A constant voltage device is constituted by the capacity C1 and an FETE16. This constant voltage device is connected between the power source VDD and the potential VD1, and as a result the logic amplitude can be reduced down to (VDD-VT) at the input/output side of the enhancement mode MOSFETE13, E14 and E15 each to increase the switching speed. |
