| 摘要 |
PURPOSE:To stabilize a threshold value, and to vary a hysteresis width, by providing a reference voltage generation circuit which generates a prescribed threshold value voltage, a comparator between each threshold value voltage, and an input voltage, and a latch circuit which outputs a hysteresis characteristics. CONSTITUTION:A reference voltage generation circuit I voltage divides a power source voltage Vcc, and generates a threshold value voltage Vth1 at a point P1, and a threshold voltage Vth2(<Vth1), at a point P2. A comparator II compares an input voltage Vin with the voltage Vth2at transistors TR P1, P2, N1, and N2, and compares the input voltage Vin with the voltage Vth1 at TRP3, P4, N3, and N4, and inputs voltages VN2 and VN4 which are results decided by nodes N2, and N4 respectively, to an output latch circuit III. The voltages VN2 and VN4. change to '0' or '1' by the input voltage VIN, and the outputs VOUT1 and VOUT2 of the circuit III change corresponding to the '1' or '0' of the VN2 or the VN4, and the output having the hysteresis width of a difference between the threshold values Vth1 and Vth2is generated, Therefore, it is possible to obtain the Schmitt circuit capable of varying an input threshold value by coupling the circuits I-III.
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