SU440647A1 - Comparator - Google Patents

Description

one

The invention relates to a pulse technique, namely, threshold devices.

Known comparator containing the starting node and the regenerative amplifier transistors.

However, the known comparator has low reliability.

The purpose of the invention is to test reliability.

For this, a / C-circuit is inserted into the comparator, connected between the emitter of the transistors of the regenerative amplifier, the base of the p-n / 7-type transistor of the amplifier is connected to the collector of the p-n-p-type transistor, the base of which is connected through the starting node diode to the collector of the transistor pnp-type conductivity.

The drawing shows a schematic diagram of a comparator.

The combinator contains a starting element made in the form of a diode capacitive bridge: diodes 1, 2, capacitor 3 connected to the source of the reference voltage 4 through a resistor 5, and capacitor 6 connected to the source of the input voltage 7 through a resistor 8, and a regenerative amplifier, performed on transistors 9, 10 of different types of conductivity, having a / C-circuit assembled on a resistor 11 and a capacitor 12.

The comparator works as follows.

In the initial state, when the negative

input source voltage

7, the absolute value is less than the voltage of the source 4 of the reference voltage, the diode 1 of the starting organ is closed. No generation occurs since the collector current of the transistor 9, determined by the resistance of the resistor 13, flows from the power source 14,

the emitter-base transition of the transistor 10. The collector current of the transistor 10, determined by the resistance of the resistor 15, flows through the resistor 16, and with proper selection of the ratio of the resistances of the resistors 15 and

16, at the cathode of diode 2 of the positive feedback circuit of the amplifier, a blocking potential is positive with respect to its anode. By increasing the input voltage to

the magnitude higher than the voltage of the reference source opens diode 1 and a positive feedback circuit arises through capacitors 3, 6, diode 1 from the collector of transistor 10 to the base of transistor 9. Moreover

the capacitors 3, 6 are chosen with sufficiently small capacitances and the circuit ensures only the formation of the pulse front. Further, due to the opening of both transistors 9 and 10, it is possible to remove

the closing potential from diode 2 and the closure along it of the positive feedback circuit. When the transistors are opened, the capacitor 12 is discharged through the emitter-base and collector non-transitions, ensuring the saturation of the transistors. In this case, a negative potential appears on the collector of triode 10 and the base of triode 9, almost equal to the voltage of source 14. Thus, a resistor 17 connected between the base of triode 9 and the common point of the circuit can be used as a load. The pulse duration is determined by the time during which the discharge current of the capacitor 12 does not decrease to the value at which the triodes go out of saturation, as a result of which they are locked regeneratively. The duration of the pause between two successive pulses is determined by the voltage recovery time at the capacitor 12 charged through the resistor 13.

Subject invention

A comparator containing a starting node and a regenerative amplifier with transistors, characterized in that, in order to increase reliability, a / C-circuit is inserted in it connected between the emitters of the transistors of the regenerative amplifier, and the base of the transistor of pnp-type conductivity of the amplifier is connected to the collector of the pnp-type transistor, the base of which is connected through the diode of the starting node to the collector of the pnp-type transistor.

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