| 摘要 |
PURPOSE:To obtain a comparator with hysteresis where the hysteresis width is narrow, the amount is constant and no error exists in the direction by using two-stage differential amplifier circuits and a constant current circut and obtaining an input of the 2nd stage amplifier circuit symmetrically from the collector of the amplifier circuit of the 1st stage. CONSTITUTION:Compared voltages y, x (x is a mean value of y) are inputted to bases of transistors (TRs) Q13, Q14 vis resistors R9, R8. In flowing a current to the resistor R8 in the direction from (x) to (k) or from (k) to (x), the input (k) is increased or decreased. The currents have the same absolute value but different sign. Current values I7, I8, I9 of the constant current circuit are all equal and the relation of IK=2IO exists, the bipolar hysteresis is given accurately and the width is narrowed. The offset is reduced by taking an input of the differential amplifier circuit of the 2nd stage symmetrically from collectors l, m of the TRs 13, 14. One of the input of the said amplifier circuit is zeroed without fail by adjusting the difference between the output of the differential amplifier circuit of the 2nd stage and the input DC level by means of diodes D1-D4, D5-D8. One of the TRs Q15, Q16 is turned off completely. |
