| 摘要 |
PURPOSE:To execute a stable operation when an electric power source is turned on without providing an actuating circuit, by connecting the first and the second current mirror circuits to the control terminal of a differential pair transistor which is operated in accordance with a voltage level of an input signal. CONSTITUTION:When turning on an electric power source, a differential pair transistor TR Q15 is turned on because the base potential of the TR Q15 is lower than the emitter potential, and the first current flows to the earth through a constant-current circuit CS1, the TR Q15, resistances R11, R12 and a TR Q12. By this current, a TR Q11 is turned on, the second current flows through TRs Q13, Q11 and an R13, by which a TR Q14 is turned on, and the third current flows through the R12 and the TR Q12. In this case, by a current mirror circuit constituted of the TRs Q11, Q12 and Q13, Q14, voltage of a point A is held at a prescribed level and attains reference voltage. When an input signal Vin is in an L level, a current flowing to the TR Q15 and a diode D1 increases, the current flows to TRs Q17, Q16, output voltage Vout is in an L level, and when the Vin in an H level, the Vout attains an H level, and input and output are varied in phase. |
