SU866729A1 - Multi-function pulse-width modulator - Google Patents

Description

The invention relates to analog computing and can be used to build time-pulse multiplying devices and frequency quadrators.

Known pulse-width modulator 5, containing an integrator, a threshold element, a bipolar reference signal source, an electronic key GN.

Its drawback is the ^{complexity, 0} Nosta constructive solutions.

The closest in technical essence to the proposed invention is a pulse width modulator comprising an integrator ¹⁵ for operator-insulating amplifier, whose input is connected to the input bus and the comparator operational amplifier f2].

A disadvantage of the known device is low accuracy.

The purpose of the invention is improving accuracy.

This goal is achieved by the fact that in a pulse-width modulator containing an integrator on an operational amplifier, the input of which is connected to the input bus, a comparator on an operational amplifier, an integrator output through the first and second counter-active zener diodes is connected to a non-inverting input of the comparator, which is connected through the first resistor to the common bus, the output of the comparator through the third and fourth counter-active zener diodes is connected to its inverting input and through the second resistor to the common bus, I invert rd input of the integrator via a third resistor connected to the output of the comparator via a fourth resistor and - the non-inverting input of the comparator.

The drawing shows a diagram of the proposed device.

The device comprises an integrator 1, consisting of a first operational amplifier 2, an input resistor 3, a capacitor 4, a first 5 and a second 6 zener diodes, a first resistor 7, a comparator 8, consisting of a second operational amplifier 9, a third 10 and a fourth 11 zener diodes, _{5 a} second resistor 12, the third resistor 13, the fourth resistor 14.

Device. Works as follows. 10

When applying to the operational amplifiers the supply voltage, the comparator 8 is set to one of the stable states corresponding to the breakdown of one of the zener diodes 10 or 11. The voltage at the output of the comparator will be equal to the sum of zener voltage stabilization punched and the voltage drop across the resistor 7. ₂₀ chenie Zener included in the negative feedback loop provides the unsaturated mode comparator for. . 4 - - the potentials of both its inputs are almost equal to this. This voltage ₂₅ is also supplied to the inverting input of the integrator 1 through the resistor 13. The voltage at the output of the integrator 1 will change linearly to the level corresponding to the voltage difference of the ₃ θ battle of one of the zener diodes 5 or 6 and the voltage across the resistor 7. Moreover, through the resistor 7 will flow a current pulse due to the output voltage of the integrator I. The direction of the current will be opposite to nej relative to the current flowing through the voltage divider on the resistors 14 and 7. The potential of the non-inverting input of the comparator 8 while changing GSI and the comparator 8 will move to another stable state. Further, all processes in the circuit will be repeated. Thus, self-oscillations will occur in the circuit. Assuming pairwise identity -. Zener 5, Bi 10, 11, then at ⁴⁵ The relative presence of the input control voltage-g zheniya output device is generated symmetric rectangular. voltage. When a control voltage is applied through a resistor 3 to ^{50, the} input of the integrator 1, the output voltage of the circuit becomes asymmetric due to a decrease in the integration time when the comparator voltage and the control voltage are identical

The operation of the device is described by the following relations:

*4

C j

(1)

where ίΐς is the voltage at the output of the integrator, C is the capacitance of the integrating capacitor 4, U c is the voltage at the output of the comparator, and _c is the input control voltage, R ^ is the resistance of the resistor 13, is the resistance of the resistor 3, U _CT is the stabilization voltage of the zener diodes 5 and 6, U ₇ is the voltage across resistor 7, is the integration time with decreasing voltage at the integrator output, t ^ is the integration time with increasing voltage at the integrator output.

Having determined the integration times t _Ί and t ^ from equations (1) and (2), we obtain the relations for the relative difference of the durations Z and the repetition frequency f of the output pulses

¢ - _J 1 Г Uk at η.

~ t ₄ + -t _a '4C [ _4g (о _st- u ₇ ) r | u _k (u _Ct -u ₇ ) 4' - £ о ~ ^ о. ^{and ί} 4 (4) '__ _Ν and to ^{WHERE £} 0'4CHF ^ (and _With t-i ₇ ) - ^ the frequency of the output pulses in the absence of an input control voltage.

As can be seen from expressions (3) and (4), the proposed device can be used as a pulse-width modulator and as a frequency quadrator.

Connecting the integrator I to the input of the comparator 2 through counter-connected zener diodes 5 and 6 provides, firstly, an improvement in the quality of integrations, since until the breakdown of one of the zener diodes 5 or 6, the operational amplifier 2 of the integrator I is loaded only with a recharge current of the same polarity, and increase the integration time j when they are bipolar.

capacitance, secondly, the transition process of switching the circuit from one state to another is improved, since the integrator voltage is supplied to the input of the comparator through a small di. the dynamic resistance of the punched zener diode, as a result of which the dependence of the switching moment on the instability of the threshold of the comparator decreases.

Claims (2)

The invention relates to analog computing and can be used to build time-pulse multiplying devices and frequency quadrants. A pulse-width modulator is known, comprising an integrator, a threshold element, a source of a two-polar reference signal, an electronic key p1. The disadvantage of it is the complexity of the constructive solution. The closest to the technical essence of the present invention is a pulse-width modulator containing an integrator on an operational amplifier, the input of which is connected to the input bus, and a compressor on the G23 operational amplifier. A disadvantage of the known device is low accuracy. The purpose of the invention is to increase accuracy. The goal is achieved by the fact that in a pulse-width modulator containing an integrator on an operational amplifier whose input is connected to an input bus, a comparator on an operational amplifier, the integrator's output is connected via the first and second counter-current zener diodes to the non-inverting input of the comparator through the first resistor connected to the common bus, the output of the comparator through the third and fourth counter-included Zener diodes is connected to its inverting input and through the second resistor to the common bus, inverti The integrator's input is connected via a third resistor to the comparator output and through a fourth resistor to the non-inverting comparator input. The drawing shows a diagram of the proposed device. The device contains an integrator 1 consisting of a first operational amplifier 2, an input resistor 3, a capacitor 4, the first 5 and second 6 zener diodes, the first resistor 7, a comparator 8 consisting of the second operational amplifier 9, the third 10 and fourth 11 zener diodes, the second resistor 12, the third resistor 13, the fourth resistor 14. The device. works as follows. When applied to the opamp power supply, the comparator 8 will be set to one of the stable conditions, corresponding to the breakdown of one of the zener diodes 10 or 11. The voltage at the output of the comparator will be equal to the sum of the voltage stabilized by the broken Zener diode and the voltage drop across the resistor 7. The inclusion of the Zener diodes in the negative feedback circuit provides an unsaturated comparator mode, according to 4) the potentials of its two inputs are almost equal. This voltage is also given to the inverting input of the integrator 1 through the resistor 13. The voltage at the output of the integrator 1 will vary linearly to a level corresponding to the voltage difference across one of the Zener diodes 5 or 6 and the voltage on the resistor 7. resistor 7 will flow impulse due to the output voltage of integrator 1. The direction of the current will be opposite to the current flowing through the voltage divider of resistors 14 and 7. The potential of the non-inverting input of the comparator 8 will change comparo torus 8 go into another stable state. Further, all processes in the circuits are repeated. Thus, auto-oscillations will appear in the scheme. If we assume the pairwise identity of the stabilizers 5, 6 and 10, 11, then in the absence of an input control voltage, a symmetrical right-angle voltage will be generated at the output of the device. When a control voltage is applied through a resistor 3 to the input of the integrator 1, the output voltage of the circuit will become asymmetric due to a decrease in the integration time in the case when the voltage of the comparator and the control voltage have the same polarity and an increase in the play time. when they are differently polarized. 8 4 The operation of the device is described by very thin relations: (UCT-U) l 5au, .. fS f-. at, w) de U is the voltage at the output of the integrator, C is the capacitance of the integrating capacitor 4, and k is the voltage at the output of the comparator, Uu, the input control voltage is the resistance of the resistor 13, the resistance of the resistor 3, and the sgg stabilization voltage 5 and 6, U- - firing on the resistor 7, t - integration time with decreasing voltage at the integrator output, t integrating time with increasing apr at the integrator output. Determining from the equations (l) and (2) of the integration circuit t .., and t / j, we obtain the relations for the relative aptitude of the durations t and the repetition frequency f of the output pulses .i :, ,,, (UcT-l 7) th | Qi I (4) where: Eo-4Ch, y (ist-i-g) the frequency of the output pulses in the absence of an input control voltage. As can be seen from expressions (W) and (4) | The proposed device can be used as a pulse width modulator and as a frequency quad. Connecting the integrator I to the input of the comparator 2 through counter-switched Zener diodes 5 and 6 provides, firstly, an improvement in the quality of the integrations, because until one of the Zener diodes 5 or 6 is broken down, the operational amplifier 2 of the integrator 1 is loaded only with a recharge current, the transition process of switching the circuit from one state to another, since the voltage of the integrator is fed to the input of the comparator through the small dynamic resistance of the punched zener diode, as a result of which the dependent imost switching moment from instability threshold comparator. Invention Formula A multifunctional pulse-width modulator containing an integrator on an operational amplifier, whose input is connected to an input bus, a comparator on an operational amplifier, characterized in that, in order to improve accuracy, the integrator output is connected to the non-inverting input through the first and second counter-oscillators comparator, which sources are taken into account in the examination I. Korn G. and Korn T. Electronic analog and analog-digital computers. M., Mir, 1967, with. 357-361. one 2. Conference on precision electromagnetic measurements. Digest, New York, N.Y. IEEE, 1978, p. 147148, fig. 2. 9. 6 the first resistor is connected to the common bus, the comparator output through the third and fourth zener diodes connected to it is connected to its inverting input and through the second resistor to the common bus, the inverting input of the integrator through the third resistor is connected to the comparator output and through the fourth resistor to a non-inverting input comparator. 5 s /