SU725220A1 - Comparator on transistors of different conductivity type - Google Patents

Description

(54) COMPARATOR ON TRANSISTORS OF DIFFERENT CONDUCTIVITY TYPE

the compared signal, is included in the collector-base connection of transistors. To the emitter of transistor 1 is connected to the midpoint of the RC-divider with a resistor 5 and a capacitor b. An RC divider is connected between the supply j and the common bus. A reverse-bias bias source is connected to the base of transistor 2 through a resistor 7. The output load of the comparator is a resistor 8. Resistors 9 and 10 may additionally be included in the input circuits of the comparator pa-tor, shown in the diagram by dashed lines.

The comparator works as follows.

In the initial period of the comparator operation, the supply voltage E and the displacement E (, „, the reference Uon and the compared IR voltage are supplied to the input terminals. During this period, the transistors and comparator diodes are clamped, which ensures a high noise immunity to a variety of interference. During operation, the compared voltage changes in the direction of approach to the reference level 25 UQ5. On the capacitor 6, the voltage Uc increases, reaching the reference level UQ at tj. At the same time, the transistor 1 goes into active mode the bots and the diode 3 is turned off; the transistor JQ resistor 2 and diode 4 are still closed in the locked state. When choosing a sufficiently low resistance of the resistor 7 and a large resistance 5, the bias source B may be absent in principle. After opening the transistor 1 and diode 3. The comparator noise immunity to changes in the electric mode of operation of the transistors remains at a high enough level. Thus, changes in the voltage of the source 40 of the power supply E "change only the bias current passing through the transistor 1 and the diode 3. Moreover, in other changes transistor element 2 is in the closed state 45 in view of the small voltage drop across the rezistre 7.Diod 4 in the positive feedback circuit cs communication tranzisto15ov not otpiraets ratios due i.r voltage UQ. When the UQ voltage is compared to JQ (, p is the value of the reference level Uon, diode 3 is locked and diode 4 is unlocked. Since diode 4 is connected to the positive feedback circuit between transistors 1 and 2, when it is unlocked, a regenerative rise occurs base and collector currents of the transistors, which are transition tv saturated or close Ti fTeMy state. On resistors 7 60 and 8, the effective

At the output and at the output of the comparator, a signal appears indicating the instant of equality of the input voltages. The presence of resistor 10 in the circuit increases the speed of the regenerative switching process of the transistors. Resistor 9 is inserted to compensate for the effect of resistor 10.

Since transistor 1 is still in active mode before the time point, it has almost no effect on the comparison process. The comparator error of the comparator is mainly determined only by the difference in the thresholds for unplugging the diodes 3 and 4, for which it is small in a wide range of working temperatures.

In order to allow the comparator to increase the voltage with the voltage of the reference level, the power supply and the common bus should be swapped and the input signals should be made relative to the new common bus.

Comparative tests of this type of comparator with the known ones have shown that OH; it has a high comparison accuracy of cPUcp O - 30 MB, a high noise immunity to pulsed changes of the supply voltage of SUEP 1100%, comparison of high voltage levels of UOR O - 60 V is acceptable; high speed, low tripping current and small parasitic capacitance at the signal input.

Claims (2)

1.Tkacheva L.I. Voltage Comparison Chart. M., Electronics, 1st issue -2 (152), 1970, May, p. 21, Fig. 15. 2.Vazhenina 3.p., Pudrikov E.V. Transistor pulse generators millisecond range. M., Sov. Radio, 1974, p. 96, fig. 3 and 4 (prototype). bus. , Ewt T “p gsn C