SU1106005A2 - Sawtooth voltage generator - Google Patents

Abstract

POWER VOLTAGE GENERATOR according to ed. St. 1018210, characterized in that. in order to ensure the constant duty cycle of the voltage being formed in a wide frequency band, the second Miller integrator is entered into it, the second key input of which is connected to the power bus, the control input - with the second control input of the device, and the output - with the input of the first key and the input of the second Miller integrator, the output of which is the second output of the device.

Description

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(L

E) The invention relates to a pulse technique and can be used, for example, in scanning circuits of electron beam oscilloscopes. According to the main auth. No. 1018210 is a well-known saw-tooth oscillator, which contains Miller's integrator, includes a load and a first mutator connected in series, a time specifying a capacitor, an amplifying element, a key; the control input of which is connected to the control bus, the output is connected to the input of the integrator, a second switch, the first input of which is connected to the input of the Miller integrator, the time is passed, the resistors are applied to the power bus, the diodes, the reference voltage, the code generator , the decoder, the input of which is connected to the output of the code generator, the first outputs are connected to the control inputs of the first switch, the second outputs with the first control inputs of the second switch, the second control inputs of which are connected to the output source and the reference voltage, and the second Inputs, to the common bus of the device, the outputs of the first switch, through diodes, are connected to the load Sh. The disadvantage of the device is that the duty cycle of the generated signals does not remain constant. At high frequencies, this constancy becomes even more noticeable due to the small values of the mapped sawtooth signal durations and blocking pulses. The purpose of the invention is to ensure the constant duty cycle of the generated voltage in a wide frequency band. The goal is achieved by the fact that a sawtooth generator containing a Miller integrator, including a load and a first switch connected in series, a time specifying a capacitor, an amplifying element, a key whose control input is connected to the control bus, the output to the Miller integrator input, the second the switch, the first input of which is connected to the input of the Miller integrator, the output through time the driving resistors - to the power bus, the diodes, the reference voltage source, the code generator, the decoder, whose input Connected to the code generator output, the first outputs are connected to the control inputs of the first switch, the second outputs are connected to the first control inputs of the second switch, the second control inputs of which are connected to the output of the reference voltage source, and the second inputs to the common input bus. the first switch is connected via diodes to the load; a second Miller integrator is entered, a second switch, the input of which is connected to the power supply bus, the control input to the second control input of the device, and the output to the input key and the input of the second Schller integrator, the output of which is the second output of the device. FIG. 1 shows the structural electrical circuit of the proposed device; in fig. 2 - plots showing his work. The device contains Miller integrator 1, which includes the load 2 and the first switch 3 connected in series, the capacitor 4, the setpoint time and the key 5, whose control input is connected to the control bus 6, the output to the Miller integrator input, the second switch 7, the first input connected to the input of the Niller integrator, the output of the clock time setting resistors — to the power bus, diodes 8, the voltage source 9, the code generator 10, the decoder 11 whose input is connected to the code generator output, the first outputs are Inen with the control inputs of the first switch, the second outputs with the first control inputs of the second switch, the second control inputs of which are connected to the output of the reference voltage source, and the second inputs to the common bus of the device, the outputs of the first switch through diodes connected to the load, the second Miller integrator 12, the second key 13, whose input is connected to the power bus, the control input to the second control input of the device, and the output to the input of the first key and the input of the second Miller integrator, whose output is the second output of the device. The second Milleoa 12 integrator is built similarly to the first on capacitors 14, diodes 15, switch 16, the second; the switch contains the first group of transistors 17, the second group of transistors 18, resistors 19.

The device works as follows.

At the command of the code generator 10, a signal is generated in the form of a binary code, which is converted by the decoder 10 into a decimal or some other code. Depending on the frequency range of the sawtooth signal, one of the transistors of the switch 3 of the first Miller integrator 1 is opened with a signal from the first output of the decoder 11. At the same time, the signal from the second output of the Shush 11, one of the transistors of the first group of the switch 7 is closed, and one of the transistors of the second group closed in the source state of source 9, opens. A square impulse (Fig. 2a) entering the first control input of the device with boundary levels +11 and (and relative common bus) closes for a period of action of the voltage -U (Fig. 2, interval t - tj), Key 5 and the amplifier of the first Miller 1 integrator, resulting in the following circuit: power source (+) - load 2-diode 8-capacitor 4 transistor 18-resistor 19-power source (-), a capacitor 4 is charged. A sawtooth is formed at the first output of the device voltage corresponding to the forward path of the oscilloscope sweep (fig. 2b) interval t - tj). At the same time, the second control input of the device is affected by a rectangular positive-polarity blocking pulse + and (Fig. 2c), which opens the key 13. The capacitor 14 starts to discharge, corresponding to the signal decay in the time interval t - t (Fig. 2d) at the second output of the device. Upon reaching the sawtooth signal (Fig. 2b) at the first output of the device of a given level at time tj, the control pulse (Fig. 2a) at the control input of the key 5 and the blocking pulse

(Fig. 2c) at the control input of the key 13 change its polarity, as a result of which the key 5 opens and the key 13 closes. At the time t, the time specifying the capacitor 4 begins to discharge. Since the capacitance time of the condenser 4 is less than the capacitance of the capacitor 14, the charge is redistributed from the time of the driving capacitor 4 to the capacitor 14 tj tif after the process of redistributing the charges (time t, fig. 2d) capacitor 14 in

tn - t time span. Because of the small active resistance in the circuit of recharging capacitors, the steepness of the increase in the output signal in the interval tj - t considerably exceeds the analogous parameter in the interval C - tg. At time tg, the amplitude of the signal at the second output reaches the level at which the polarity of the blocking pulse changes (Fig. 2c), and the cycle of operation of the device is repeated.

Since the resistor 19 of the second switch 7 is used simultaneously as the time master element of the first Miller integrator and the element of the charge circuit of the BTOpoio Miller integrator 14 charge circuit (determining the blocking time), the time constants of these circuits are respectively Tfj ,,, T K "Cd, ( the indices of the elements correspond to the designations of Fig. 1). Therefore, if for all discretely switched working frequencies the ratio is Const, then the duty ratio of the sawtooth signal (T +% d) / Tn 1 + const does not depend on the frequency of the signal.

A sawtooth generator (FPG) can be taken as the base object.

This makes it possible to ensure the constant porosity of the generated voltage in a wide frequency band.

Vat. 2

Claims (1)

Sawtooth Generator VOLTAGE St. No. 1018210, characterized in that, in order to ensure the constancy of the duty cycle of the generated voltage in a wide frequency band, the second Miller integrator is introduced into it, the second key, the input of which is connected to the power bus, the control input with the second control input of the device, and output - with the input of the first key and the input of the second Miller integrator, the output of which is the second output of the device.