SU362461A1 - ANALOG-DIGITAL CONVERTER - Google Patents

Description

one

The invention relates to a pulse technique and can be used for analog-to-digital conversion of a millivolt range voltage.

A analog-to-digital converter is known, which contains an amplitude-digital code with an expander, a control unit, a block of exemplary resistors with a switch, a switch and a power source. However, the switch key in the circuit of the measured signal degrades the sensitivity and accuracy of the conversion.

The aim of the invention is to increase the sensitivity and accuracy of the conversion. To achieve this goal, a cumulative inductance and a transformer on a core with a rectangular hysteresis loop are introduced into the converter, the primary winding of which is connected in series with the cumulative inductance to the source of the voltage being converted, and one secondary winding is connected through parallel connected a block of exemplary resistors with a switch and a switch are connected to a voltage source; another, a secondary winding is connected to At the converter input, an amplitude-digital code with an expander m, while the control input of the key is connected to the output of the control unit.

FIG. 1 shows a functional diagram

converter; in fig. 2 - idealized magnetization curve.

The analog-to-digital converter has a block / control and a converter 2 amplitude-digital code. The sensitivity of the conversion is varied by using a block of 3 exemplary resistors switched on by switch 4 parallel to the key 5. Resistor 6 limits the amount of current / i flowing through the winding 7 of the transformer 8 from the voltage source 9. The required current value / bias 2 is set using potentiometer 10. There is also a cumulative inductance // and inductance 12, designed to increase the reactance of the winding circuit 13. The output voltage is removed from the winding 14 of the transformer 5 and fed to the input of the converter 2 amplitude-digital code .

In the initial state, a current / 3 flows through the input circuit. When the key 5 is closed along the winding 7 of the transformer 8, a current / s flows in the opposite direction to / s, and its value provides a positive saturation of the core of the transformer 8 in the entire range of current / 3. On a signal from control unit 1, key 5 is opened and the core goes from state L (see Fig. 2) to state D. On section AD, the inductance of the core windings

equals zero. At point D, the inductance increases in jumps and, for the ideal case, in the segment DN goes to infinity. A jump in the inductance in the input circuit causes the current in the output circuit to stop, while the current / 3 flowing through the storage inductance 11 does not change and creates a voltage drop on the equivalent load resistance of the transformer, which is equal to the emf. self-induction arising on inductance //, and is proportional to the input voltage.

The equivalent load impedance consists of parallel-connected open-key resistors, a reference impedance, and an input impedance of the transducer 2: amplitude-digital code; Since the reference resistance is selected one to two times less than the resistance of the open key, the latter can be ignored.

When the output voltage is maximum

and and

- - in

Max

where g is the active resistance of the input value;

R - equivalent load resistance.

D

Since ;: 1, the output impulse impulse significantly exceeds the value of the converted signal.

After receiving the output pulse, the switch 5 closes and the core of the transformer 8 goes to state L.

To compensate for the hysteresis of the core, a bias winding 14 is used, in which a current flows, creating a voltage field Poison.

Subject invention

An analog-to-digital converter containing an amplitude-digital converter

a code with an extender, a control unit, a block of exemplary resistors with a switch, a switch and a voltage source, characterized in that, in order to increase the sensitivity and accuracy of the conversion,

accumulative inductance and a transformer on a core with a rectangular hysteresis loop, the primary winding of which is connected in series with the storage inductance to a source of transformable voltage, and one secondary winding through a parallel connected unit of sample resistors with a switch and a key connected to a voltage source, another secondary winding connected with an inverter input, an amplitude-digital code with an expander, wherein the control input of the key is connected to the output of the control unit.