SU1647875A1 - Time-to-voltage converter - Google Patents

Abstract

The invention relates to a pulse technique and is intended to emit signals in the form of a constant voltage, the magnitude of which is proportional to the duration of the input pulse. The purpose of the invention is to increase the speed and accuracy - it is achieved by introducing diodes 1-4, current source 11, capacitor 13, resistor 17. inverter 10 containing transistors 20, 21, sources 22, 33 and resistors 24-27, and a one-shot 9, containing an operational amplifier, two current sources, two diodes, a capacitor, and a resistor. The converter also contains a diode 5, an input bus 7, an output bus 8. a capacitor 12, operational amplifiers 14, 15, a resistor 16 and a normally closed switch 18. 2 Cp f-ly, 3 ill.

Description

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The invention relates to a pulse technique and is intended to emit a signal in the form of a constant voltage, the magnitudes of which are proportional to the duration of the input pulse.

The aim of the invention is to increase speed and accuracy.

FIG. 1 is a schematic diagram of a time-to-voltage converter; in fig. 2 - diagrams of his work; in fig. 3 - one-shot circuit.

The time-voltage converter contains diodes 1-6, input bus 7, output bus 8, one-shot 9, inverter 10, current source 11, first 12 and second 13 capacitors, first 14 and second 15 opamps, first 16 and second 17 resistors , normally closed key 18. The input bus 7 is connected to the input of current source 11, to the first output of diode 1 and through the one-shot 9 to the first output of diode 2 and to the input of inverter 10, the first output of which through diode 3 is connected to the first output of resistor 16 and . non-inverting input of the operational amplifier 14, and the second output through diode 4 is connected to the first output of the resistor 17 and non-inverting input of the operational amplifier 15. The outputs of operational amplifiers 14 and 15 through the corresponding diodes 5 and 6 are connected to the output bus 8 and through a capacitor 13 - with a common bus 19 connected via key 18 to the output of current source 11.

Inverter 10 includes transistors 20 and 21, voltage sources 22 and 23, and resistors 24-27. The one-vibration 9 contains an operational amplifier 28, sources 29 and 30 current, diodes 31 and 32, a capacitor 33, a resistor 34.

The purpose of the inverter 10 is to form a high voltage of different polarity at its outputs during the absence of it. voltage input and the formation of a high voltage of opposite polarity at its outputs during the entire time that a control voltage is present at its input.

The purpose of the one-shot 9 is to form at its output a square-shaped pulse of a predetermined duration, the leading edge of which coincides with the falling edge of the pulse applied to the input of the one-shot.

The operation of the time-voltage converter is as follows.

In the absence of UBX pulses on bus 7 (see time point ti), capacitors 12 and 13 are discharged, diodes 5 and 6 are biased in the opposite direction, current of current source 11 is absent, and switch 18 is closed.

Suppose that at the time t2 the first impulse UBx passes to the bus 7 with the specified duration (see Fig. 2a). Starting from this moment, from the output of the current source 11, which can be used, for example, a resistor, a diode connected in series, or well-known controlled current generators on transistors or on operational amplifiers, the current through which the capacitor 12 is charged flows as at this point in time, the switch 18 is disconnected due to the arrival at its input of the control of a high positive voltage from the bus 7 through the diode 1. The state of the operational amplifiers 14 and 15 remains unchanged due to the fact that through the diodes 3 and 4, their non-inverting inputs receive high voltages, much larger in magnitude than the maximum possible charge value of the capacitor 12.

The resistance values of the resistors 16 and 17 are used large, so the insignificant influence of the currents of these resistors on the charge value of the capacitor 12 is provided. In addition, the currents of these resistors flow counter to and therefore they cancel each other out. At the time ts, the back edge of the input pulse is formed on the bus 7, the current from the output of the current source 11 is zero. On the falling edge of the output pulse, a one-shot 9 is started, a positive pulse from its output, first, through diode 2 keeps key 18 in the open state, and secondly, this pulse arrives at the input of inverter 10. Transistor 21 is saturated, and diode 3 shifted in the opposite direction. At the same time, saturation of the transistor 20 occurs, on the collector of which a negative potential is formed, from which diode 4 is shifted in the opposite direction.

The non-inverting inputs through the resistors 16 and 17 receive the voltage of the capacitor 12 of positive polarity, as a result of which the output of the operational amplifier 14 has a positive polarity, the diode 5 is unlocked and due to the deep feedback the capacitor 13 acquires a charge equal to the charge on the capacitor 12. At time t4, the back edge of the output pulse is generated from the output of the one-shot 9, the switch 18 is closed and the capacitor 12 is quickly discharged through it. At the same time, at time tz, diodes 3 and 4 are unlocked, and diodes 5 and 6 are displaced in the opposite direction and the charge on the capacitor 13 does not change further until the formation of the trailing edge of the next pulse on the bus 7.

In the event that the time duration on the input bus 7 is subsequently unchanged, then the output voltage on the bus 8 is constant, without any pulsations.

If, at the time moment te, a pulse of shorter duration arrives, then by the time t, the capacitor 12 is charged to a smaller value, therefore, when diodes 3 and 4 are blocked, the voltage on the positive polarity of the capacitor 13 is equal to the previous value, i.e. on the capacitor 12. Therefore, at the output of the operational amplifier 15, the voltage decreases sharply and the capacitor 13 through the diode is quickly discharged to the value of the voltage on the capacitor 12.

Thus, the performance of the time-voltage converter is always equal to one period at any frequency of the input pulses.

Claims (3)

Claim 1. Time-voltage converter containing two operational amplifiers, the inverting input of the first of which is connected to the output bus, the first capacitor, the first output of which is connected to the common bus, and the second to the first output of the normally closed switch, the first resistor and the first A diode, characterized in that, in order to improve speed and accuracy, a one-shot, current source, inverter, second capacitor, second resistor and five diodes are inserted into it, the one-shot input is connected to the input bus and to the input and current source, the output of which is connected to the second output of the first capacitor and, respectively, through the first and second resistors with non-inverting - inputs of the first and second operational amplifiers, the outputs of which respectively, the first and second diodes are connected to the output bus, the inverting inputs of the operational amplifiers are combined and connected via the second capacitor to the common bus, the one-shot output through the third diode is connected to the control output of a normally closed switch that is connected to the input bus through the fourth diode, the second conclusion a normally closed switch is connected to a common bus, the inverter input is connected to the output of a single vibrator, and the outputs of the inverter are connected via the fifth and sixth diodes to the non-inverting inputs of the first and second operational amplifiers, respectively. 2. The converter according to claim 1, that is, that the inverter is made on two transistors of different conductivity type, the emitter of the first of which is connected to the input of the inverter, the base through the first resistor - with a common bus and the collector - with the first output of the inverter and through the second resistor with the base of the second transistor, the emitter of which is connected to the first power supply bus and via the third resistor with its base, and the collector is connected to the second output of the inverter and through the fourth resistor to the second power supply bus. 3. A converter according to claim. Characterized in that the one-shot is made on a comparator, the non-inverting input of which is connected through parallel the first current source and the capacitor are connected to the common bus and through the first diode to the input of a single vibrator, which is connected via the second diode to the inverting input of the operational amplifier, which through a parallel connected resistor and the second current source is connected to a common bus, the output of the operational amplifier is connected to the output of the one-shot FIG. 2 Mu Fig.z 28