SU1309292A1 - Non-linear pulse-width modulator - Google Patents

Abstract

The invention can be used in telemetry information-measuring systems. The purpose of the invention is to improve the accuracy of the modulator. The modulator contains an integrator 1, a controlled voltage divider 3 and a comparator 9. The introduction of a switch 13, a resistor 14 and a capacitor 15 allows realizing the functional characteristic e / Γ of the modulator by directly, without using an approximation, forming the desired characteristic. This reduces the instrumental error of the modulator, since The absolute values of resistors do not affect its functional performance. 1 il. with $ (L with with about with with

Description

one

The invention relates to a pulsed technique and can be used in telemetric information measuring systems.

The aim of the invention is to improve the accuracy of the implementation of the functional characteristic / X of a non-linear pulse-width modulator by directly, without using an approximation, forming the desired characteristic.

The drawing shows a functional diagram of a non-linear pulse-width modulator.

The modulator contains an integrator 1, an output 2 of the device, a controlled voltage divider 3 having a first resistor 4, a switch 5, a second resistor b and a first capacitor 7, a first input 8 of the device, a comparator 9, a bar 10 of the sawtooth voltage, the first resistor 11 modulator, the second input 12 of the device, the key 13, the second resistor 14 and the second capacitor 15 of the modulator. The integrator 1 contains the first 1 and second 17 resistors, the switch 18, the capacitor-19, the operational amplifier 20. The resistor 4, the switch 5 and the resistor 6 of the controlled voltage divider 3 are connected

one

sequentially, with the combined outputs

The switches of the key 5 and the resistor 6 are connected to the common bus through the capacitor 7, and the free first terminal of the resistor 4 is connected to the first input 8 of the device.

The output of the com- parator 9 is connected to the control inputs of the key 13 of the integrator. 1 and the controlled voltage divider 3, one input of the comparator 9 is connected to the output of the integrator 1, and the other to the bus 10 of the sawtooth voltage, one of the terminals of the resistor 11 is connected to the second input 12 of the device, and the uncontrolled input of the integrator 1 and the first terminals of the capacitor 15 and the resistor 14 are connected to another, the second terminal of which is connected to the second terminal of the capacitor 15 via a switch 13 and the common input of the integrator 1 is connected with the combined pins of the switch 5 and the resistor 6 of the controlled voltage divider 3, with the other pin of the resistor 6 connected to a common busbar. The first terminals of resistors 17 and 16 are the controlled and unmanaged inputs of the integrator 1, respectively, the second terminal of the resistor 17 is connected via a switch 18 to the second terminal of the resistor 16 and the first input of the operational amplifier 20, the second input of which is connected to the common bus, and the output of the operational amplifier 20 through a capacitor 19 is connected to its first input and, moreover, is the output of an integrator 1.

In this case, the control inputs of the keys 5 and 18 are the control inputs of the respectively controlled voltage divider 3 and the integrator 1.

1309292

and repeats.

The device works in the following way.

The input signal U "t proportional to

the current value of the argument arrives at

input 12, reference Uo - to input 8, and sawtooth voltage with a period T - to

entry 10.

Let at the initial moment of time the keys 5, 13 and 18 are open. The input current of the operational amplifier 20 will be set by the input circuit of the unmanaged input of the integrator 1. When the switches 5, 13 and 18 are closed, the formation of the time interval begins at the beginning of the period T. The currents along the two input circuits of the integrator 1 are summed, with the resulting current going in the opposite direction to the source. The voltage produced at the output of the integrator 1 is compared at comparator 9 with a sawtooth voltage, and if these voltages coincide, the comparator 9 completes the formation of the time interval (/ interval, which causes the keys 5, 13, and 18 to return to their original open position. Current at the input of the operational amplifier 20 changes its direction and is given by the input circuit of the modulator until the beginning of the next period. Then the process

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five

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five

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In the established mode, at a sufficiently large capacitance of capacitors 7, 15 and 19, the voltage on B1) input of the integrator 1 will be determined by the functional characteristic of the device, and the currents will be controlled by the controlled and uncontrolled to my inputs of the integrator 1. Moreover, if it is assumed that the conductivities of resistors 4, 6, and 17 are taken equal to each other and equal to d, the conductivity of resistors 11 and 16 are taken equal to 2d, and the conductivity of resistor 14 is equal to 8d, then the functional dependence of the relative output duration and. The modulator pulse from the input voltage is defined as Ugx Uo © or 0 VUg-j / Uo, where in t / T is the relative duration of the generated PWM signal with pulse duration t and periodo.m T.

The formation of a working modulating characteristic without approximation, and consequently without methodological error, allows to increase the accuracy of the non-linear pulse-width modulator. This also reduces the instrumental error of the modulator, since the absolute values of the resistor values do not affect its functional characteristic.

Claims (1)

Invention Formula A non-linear pulse-width modulator containing an integrator, a controlled voltage divider, a comparator and a resistor, the controlled voltage divider being designed as a capacitor and connected in series of the first resistor, key and second resistor, the combined outputs of the key and the second resistor controlled the voltage divider is connected via a capacitor to a common bus, the control input of the switch is the control input of the controlled voltage divider, the first output of the first resistor of which is the first the input of a non-linear pulse-width modulator, the output of which is a comparator output connected to the control inputs of a controlled voltage divider and an integrator connected by its output to the first input of a comparator connected by a second input to the sawtooth bus, and the first output of the first modulator resistor is second a modulator input, characterized in that, in order to increase the accuracy of the realnation of the functional characteristics of the d / x. A key and a second resistor and a capacitor connected in series in the feedback circuit of the key are inserted into it, while the terminals of the second resistor and capacitor are connected to the second output of the first modulator resistor and to the uncontrolled input of the integrator, and the common terminals of the key and capacitor are connected to at the same time, the control key input is connected to the comparator output, the key output of the controllable voltage divider is connected to the controllable input of the integrator, and the second output of the second resistor of the controllable divides L voltage coupled to sheathe i1inoy.