| 摘要 |
PURPOSE:To perform operation even when input voltage is in the vicinity of earth potential and to increase the degree of freedom of the planning of a hysteresis width, by mounting a differential pair of transistors, a negative impedance transistor, two resistors and the first and second constant current sources. CONSTITUTION:Resistors R1 and R2 are respectively connected to differential pair transistors Q1 and Q2, and the collectors of negative impedance transistors Q3 and Q4 are connected to the bases of the transistors Q4 and Q3, respectively. When the input voltage Vin between input nodes 1, 2 is changed, the output voltage Vout between output nodes 3, 4 comes to show a hysteresis characteristic around reference voltage Vref. When the currents of constant current sources I1, I2 are set to I1, I2, the saturated voltage between the emitter and collector of Q1 is set to VCESATQ1 and the voltage between the base and emitter thereof is set to VBEQ1, the voltage Vin becomes R1(I1+I2)+VCESATQ1-VBEQ1 and, when the voltage of the resistor R1 is made far smaller than the voltage VBEQ1, operation becomes possible even in the vicinity of earth potential. Further, it becomes possible to change a hysteresis width by changing the magnitude of the current I2 and the degree of freedom of the planning of the hysteresis width becomes large.
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