SU1150747A1 - Pulse-width voltage modulator - Google Patents

Abstract

A WIDE-PULSE VOLTAGE MODULATOR, containing an error amplifier, is performed on a differential input and single output stages, the input of which is connected to the control signal bus, and the output is connected to the first input of the threshold element, the output of which is connected to the output bus, and the sawtooth generator, characterized in that, in order to increase the stability of the limitation of the output signal duty ratio, an amplitude detector, a resistive divider, two emitter repeaters are additionally introduced into it ranzistorah opposite conductivity type and two diodes, wherein reHepatopa output ramp voltage is coupled to the second input of the threshold element and the input i of the amplitude detector output koto-; connected to the input of the first emitter follower and the input of a resistive divider, the output of which is connected to the input of the second emitter follower; included in accordance with the base-emitter transitions of transistors corresponding to the emitter followers.

Description

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The invention relates to electrical engineering, namely, to a pulse technique, and can be used in sources of secondary power supply, as well as in other semiconductor controllers with a pulse-width control method, to which the reliability requirements are imposed.

The purpose of the invention is to increase the stability of limiting the duty cycle of the output signal.

Figure 1 shows the diagram of the device; 2 shows timing diagrams explaining the operation of the modulator.

The device contains an amplifier 1 mismatch, performed on the differential input and single output stages, the input of which

; connected to the control signal bus, and the output to the first input of the threshold element 2, the output of which is connected to the output width, and a sawtooth voltage generator 3, amplitude detector 4, resistive divider 5, two emitter repeaters on transistors 6 and 7 of the opposite type of conductor -ins and two diodes 8 and 9, the emitter follower outputs are connected to the corresponding power supply buses through the load resistors 10, 11 and to the outputs of the differential input stage of the error amplifier through diodes 8 and 9 connected with publicly with base-sump transistors 6 and 7 of the corresponding emitter followers. The device works as follows.

. in a way.

Input voltage, amplified

. mismatch amplifier t, is fed to the non-inverting input of the threshold element 2 (FIG. 2d). A sawtooth voltage is supplied to the other inverting input of the threshold element 2 (Fig. 2c () from the generator 3, Threshold element 2, compared to the indicated voltages, forming: RU T output pulse-width voltage (Fig. 2E) "For two-sided duty cycle limit output7472

In the modulator there is a node limiting the range of variation of the output voltage of the error amplifier 1, and the limitation of the output voltage of the error amplifier 1 does not exceed the limits (fig.2b, c) of the saw voltage. Thus, at the output of the threshold element 2, a pulse width voltage with a finite value of a finite value is always formed (Fig. 2e, 1c). The node limiting the change in the output voltage of the error, consists of an amplitude detector 4, from the output of which the amplitude value of the sawtooth voltage through the emitter follower on the transistor 6 and the diode 8 limits the range of the output voltage of the voltage amplifier from above, and the voltage divider 5, the average voltage which points through the emitter follower and developing

The diode 9 limits the variation of the output voltage of the error amplifier 1 below.

Changing the shape or amplitude of the sawtooth voltage changes

the voltage at the output of the amplitude detector 4 and, therefore, the output voltage of the error amplifier will still be within sawtooth voltage, thereby limiting the duty cycle of the modulator output pulses.

Thus, the modulator output is limited in width

a pulse from two sides, independent of the value of the supply voltage, the generator frequency and the shape of the sawtooth voltage. This circumstance leads to the fact that when using a given pulse-width modulator in semiconductor controllers with a pulse-width control method, it practically excludes the possibility of exit from

stro power of key elements

which ultimately increases the reliability of the entire control system.

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Claims (1)

WIDTH-PULSE VOLTAGE MODULATOR containing a mismatch amplifier made on the differential input and single output stages, the input of which is connected to the control signal bus, and the output to the first input of the threshold element, the output of which is connected to the output bus, and a sawtooth voltage generator, characterized in that, in order to increase the stability of the limitation of the duty cycle of the output signal, an amplitude detector, a resistive divider, two emitter followers per transistor are additionally introduced into it of the opposite type of conductivity and two diodes, the output of the sawtooth voltage generator being connected to the second input of the threshold element and the input of the amplitude detector, the output of which is connected to the input of the first emitter follower and the input of the resistive divider, the output of which is connected to the input of the second emitter follower, the outputs of the emitter followers are connected to the opposite / position tires of the power source through load resistors and to the outputs of the differential stage of the mismatch amplifier through odes included in accordance with the base-emitter junctions of the transistors of the respective emitter repeaters. SU, „, 1150747