SU533906A1 - Null oran - Google Patents

Description

one

The invention relates to a pulse technique and can be used in the construction of analog-digital converters, in control and measuring equipment.

A null organ is known, based on a differential amplifier covered by a disdio-resistive positive feedback.

However, the interference and intimacy of such an organ is low.

Also known is a noise-resistant nullorgan, made on the basis of an operational amplifier, in the positive feedback circuit of which an inertial rearrangement unit is included.

Such a null organ is protected from interference only at intervals between acoustic signals.

The purpose of the invention is to increase the immunity of the null organ.

This is achieved by the fact that a null-organ containing a differential amplifier, covered by a diode-resistive positive feedback, the inverting input of which is connected to the input source, and the output through parallel-connected drivers to the trigger inputs, inverter and dividers. element I, an additional driver, a capacitor, and two keys, with one of the inputs of the element I through the inverter H being the first

the voltage divider is connected to the output of the differential amplifier, the non-inverting input of which through the second voltage divider and additional driver is connected to the other input of the element I and through one of the keys to the capacitor, one plate of which is connected to zero and the other through

it is a key and a resistor with a power source; the control of the key inputs is connected to the trigger output.

FIG. 1 and presented the schema of the proposed null organ; in fig. 2 - timing diagrams, as described in Fig. 2, the null-organ operation (Fig. 2, a - operation without interference; Fig. 2.6 - operation with interference).

The zero orgap contains a differential amplifier 1, to the inverting input 2 of which an input signal is applied, and between the output and the non-inverting input a diode 3 and a positive feedback resistor 4 are connected.

Shapers 5 and 6 are connected to the output of the differential amplifier, which generate pulses when the output voltage of differential amplifier 1 drops from a positive value to a negative (shaper 5) and from a negative value to a positive (shaper 6). The outputs of the drivers are connected to the inputs of the trigger 7, the output of which is connected to the control input of the switch 8, the signal input of the latter through a resistor 9 is connected to the power source, and the output to the capacitor 10 and the input of the second switch 11, the control input of which is connected to the second trigger output 7, and the output to the “non-inverting input of the differential amplifier 1, to the divider and resistors 4 and 12 and to the divider on the diode 13 and resistor 14. From the voltage divider, the signal through the driver 15 is fed to one of the inputs of the element 16, the output which on coupled to the output bus 17 and the other .The inputs through an inverter 18 connected to the divider nanr voltage across the diode 19 and resistor 20 connected to the output of the differential amplifier.

Zero-orga) works as follows.

When the supply voltage to the null organ (or no input signal) is output, the maximum positive voltage is set at the output of the differential amplifier 1 due to fluctuations and a non-linear positive feedback, which sets a positive threshold voltage at the non-inverting input of the differential amplifier 1, equal to

oih

and.

and

pore

f / d + f / 4 + and ,:

where f / o is the output voltage of the differential amplifier;

f / T, is the voltage drop across the diode;

4, Ui2 - the fall of the resistance on the resistors 4, 12.

The trigger 7 is set by a reset emulsion generated when the power source is turned on, to a position in which the key 8 is open and the key 11 is closed (the reset circuit of the trigger 7 is not shown in Fig. 1).

Capacitor 10 is charged to the voltage of the power supply. When an input signal is present, when the level exceeds the voltage level at the non-inverting input, the output voltage of amplifier 1 becomes negative, and the effect of the positive feedback connection is eliminated. However, the appearance of an output voltage drop at the output of amplifier 1 causes the appearance of an emulsion at the output of the driver 5, which sets the trigger 7 to the position where the key 8 closes and the key 11 opens, and the capacitor 10 begins to discharge through resistor 12 and sequentially a connected resistor 14 and a diode 13, causing the appearance of a negative voltage decreasing on its exponent, at the non-inverting input of amplifier 1 and at the input of the driver 15.

The occurrence of a negative voltage on the inverting voltage ensures the constancy of the output voltage of the amplifier 1 when noise appears on the working (input) signal, i.e., the noise immunity increases.

The time of discharge of the capacitor 10 is chosen such that it will be able to discharge to zero until the phase of the input signal changes from positive to negative.

At the time of the transition of the input signalol value (phase change) at the non-inverting input of amplifier 1, the potential is zero. Positive feedback disabled

diode 3. At the moment of equality of the potentials on

inverting and non-inverting inputs

amplifier 1 output voltage of amplifier

becomes positive.

Pastunet regenerative process due to

enable positive feedback. The output voltage of the amplifier reaches its maximum positive voltage. The resulting voltage drop at the output of the amplifier 1 from a negative to a positive value leads to the appearance of a pulse at the output of the driver 6, setting the trigger to the position at which the key 8 is open and the key 11 is closed, the capacitor 10 starts to charge.

The apparent negative voltage drop across resistor 14 is converted by shaper 15 into a pulse whose length is equal to the duration of the pulse acting at its input and provides a pulse whose potential varies from a positive value to zero, which is necessary for normal operation of the element I 16, to the second input of which the inverted output voltage of amplifier 1 is applied.

At the output of the element P 16, i.e., on the output busbar 17, there appears a plug, the duration of which is equal to the difference of the durations of the output signal of the amplifier 1 and the output

signal shaper 15.

In the case of interference between input signals, the duration of which is shorter than the constant of the discharge time of the capacitor 10, a spurious pulse does not appear at the output of the device. The resistor 20 and the diode 19 provide a matching on the voltage (polarity) of the output of the differential amplifier 1 and the input of the inverter 18. Thus, the zero-body provides

normal operation in case of interference not only at the input working signal itself, but also between the signals.

Claims (1)

Invention Formula A zero-body containing a differential amplifier, covered by a diode-resistive positive feedback, the inverting input of which is connected to an input source, and the output through parallel-connected drivers — with trigger inputs, inverter and voltage dividers, in that the purpose increased noise immunity, an AND element, an additional driver, a capacitor, and two switches, one of the inputs of the AND element through the inverter and the first voltage divider are connected to the output of the differential amplifier, the non-inverting input of which is connected through the second voltage divider and the additional driver the other input of the element I and through one of the keys with a capacitor, one lining of which is connected to the zero bus, and the other through the other key and resistor with a power source that controls the inputs to The keys are connected to the trigger outputs. Interference Interference - f