| 摘要 |
PURPOSE:To make a high-speed operation and a low power consumption possible by introducing an impedance element, which changes the impedance in accordance with a potential difference between both ends, to a transistor transistor logic (TTL) input circuit. CONSTITUTION:Field effect transistors T1 and T2 are used as impedance elements Z1 and Z2. In a conventional circuit, resistances R1 and R2 are used. The resistance between a gate G and a source S to the potential of a drain D is shown in a figure when the gate G and the source S are set to +5V; and for the purpose of equalizing the switching speed to that of the conventional circuit, the field effect transistor T1 is set to the same 20kOMEGA as the resistance R1 of the conventional circuit at the bias point, where the drain D is 3Vf=2.4V, so that a large quantity of base current of a transistor Q2 is supplied when transistors Q2 and Q3 start turning on. The field effect transistor T2 is set to the same 5kOMEGA as the resistance R2 of the conventional circuit with the base of a transistor Q4 where the potential of a terminal OUT is a threshold voltage 1.5V of the TTL. That is, the transistor T1 is set to 5kOMEGA with D=3.1V. At this time, current consumption Icc is 0.11mA for IN=0.4V and is 0.39mA for IN=2.4V, and thus, the power consumption is reduced to a half of that of the conventional circuit. |
