RU2062548C1 - Regeneration comparator - Google Patents

Abstract

FIELD: pulse devices, instruments. SUBSTANCE: device has operational amplifier, line of controlled voltage, line of reference voltage, first and second resistors, common line, output line, field-effect transistor, which gate is connected to output of operational amplifier, which source is connected to common line. Line of controlled voltage is connected to inverting input of operational amplifier, line of reference voltage is connected to direct input of operational amplifier through first resistor. Output of operational amplifier is connected to output line and its direct input is connected to drain of field-effect transistor through direct resistor. EFFECT: simplified design. 2 dwg

Description

 The invention relates to a pulse technique and can be used in various measuring devices with tolerance control, monitoring and alarm systems. It is known A.S. USSR N1487163, class H03 K5 / 24, 1987. The device contains two operational amplifiers, four resistors, two reference voltage buses, a matching element, a delay element, a peak detector, an amplifier, two controlled resistors, a controlled voltage bus, and an output bus.

 Similar features of the analogue and the claimed device are: operational amplifier, two resistors, a reference voltage bus, a controlled voltage bus, an output bus.

 The disadvantage of this device is its complexity.

 Closest to the technical nature of the proposed device is a device for A. with. USSR N1487165, class H03K 5/24, 1987. The device contains an operational amplifier, six resistors, three input buses, a common bus, an output bus, a variable resistor, a zener diode, four diodes, a transistor.

 Common features of the prototype and the claimed device are: an operational amplifier, a reference voltage bus, a controlled voltage bus, a common bus, an output bus, two resistors.

The disadvantage of this device is its complexity, due to the fact that two reference voltages are used to form two independent switching thresholds, and also because the feedback circuit providing hysteresis of the transfer characteristic is inertial, therefore it is duplicated by an adjustable positive feedback circuit, the purpose of which
eliminate spurious vibrations.

 The aim of the proposed invention is to simplify the device.

 This goal is achieved by the fact that in the regenerative comparator containing an operational amplifier, two resistors, a controlled voltage bus, an output bus, a common bus, a field-effect transistor is introduced again, and the controlled voltage bus is connected to the inverting input of the operational amplifier, the reference voltage bus is connected through the first resistor with a non-inverting input of the operational amplifier, the output of which is connected to the output bus and with the gate of the field-effect transistor, the source of which is connected to the common bus, and the drain is ithout second resistor to the noninverting input of the operational amplifier.

 Analysis of the known technical solutions showed that the set of features that distinguish the claimed device from the prototype is unknown in the technique and together with common features provides a positive effect in the implementation of the invention.

To achieve this goal in the proposed device, the following was done:
two thresholds of operation are formed from one reference voltage with the help of a field-effect transistor operating in the key mode and a resistive divider, the choice of resistances of which can independently set the thresholds of operation;
the diode valve controlled by a bipolar transistor has been replaced by a resistive divider controlled by a field effect transistor, which eliminated the adjustable positive feedback circuit and the operation to suppress stray oscillations.

 In FIG. 1 shows a functional diagram of the device. In FIG. 2 shows the timing diagrams of the operation of the device.

 The regenerative comparator contains a controlled voltage bus 1 connected to the inverting input of the operational amplifier 2, a reference voltage bus 3 connected through a first resistor 4 to a non-inverting input of the operational amplifier 2, the output of which is connected to the output bus 5 and to the gate of the field-effect transistor 6, the source of which is connected with a common bus 7, and the drain is connected through a second resistor 8 with a non-inverting input of the operational amplifier 2.

где R₄ сопротивление первого резистора 4;
R₈ сопротивление второго резистора 8;
R_си сопротивление канала сток-исток полевого транзистора 6.The device operates as follows (see Fig. 1, 2). On the bus 3 of the reference voltage, the voltage U _et . The voltage Ud at the non-inverting input of the operational amplifier 2 is determined by the ratio of the resistances of the first and second resistors 4, 8 and the state (open and closed) of the field-effect transistor 6. The value of this voltage is

where R _{4 the} resistance of the first resistor 4;
R _{8 is the} resistance of the second resistor 8;
R _si resistance of the drain-source channel of the field-effect transistor 6.

When the field effect transistor 6 is closed, the resistance R _si is tens of Ohms, therefore, for most practical circuits
R _si > R ₄ and R _si > R ₈ .

In this case, U _d U _dv U _et .

With the open field-effect transistor 6, the resistance R _si is tens to hundreds of ohms, so for most practical circuits
R _si <R ₄ and R _si <R ₈ .

.In this case
U _d U _days

.

In the initial state, on the bus 1 of the controlled voltage, the voltage U _k is equal to zero, therefore, at the output of the operational amplifier there is a high level of voltage supplied to the output bus 5, as well as to the gate of the field-effect transistor 6, which is maintained at a high level in the closed state, i.e. at the non-inverting input of the operational amplifier 2, the voltage is U _gb . When the controlled voltage U _k increases, it is compared by the operational amplifier 2 with the voltage at its non-inverting input and when the equality
U _to U _dv
at the output of the operational amplifier 2, a low level appears, bringing the field-effect transistor to the open state, i.e. at the non-inverting input of the operational amplifier 2, the voltage becomes equal to U _days .

With a decrease in the controlled voltage U _k and when equality is reached
U _to U _days
at the output of the operational amplifier 2, a high voltage level appears. The field effect transistor 6 is closed and the comparator assumes the initial state.

.Thus, the switching of the regenerative comparator occurs when the controlled voltage reaches two different values determined by the output state of the comparator, i.e. it has a hysteresis U _g whose value is equal to

.

 Comparison with the prototype shows that the proposed device is simplified by building on fewer elements and eliminating regulatory operations.

Claims (1)

 A regenerative comparator comprising an operational amplifier, a controlled voltage bus, a reference voltage bus, first and second resistors, a common bus, an output bus, characterized in that, in order to simplify the device, a field-effect transistor is introduced into it, the gate of which is connected to the output of the operational amplifier, source to the common bus, the controlled voltage bus is connected to the inverting input of the operational amplifier, the reference voltage bus through the first resistor is connected to the non-inverting input of the operational amplifier An amplifier whose output is connected to the output bus, and a non-inverting input through a second resistor to the drain of the field-effect transistor.

Images