SU373871A1 - ALL UNION ?? i - Google Patents

Description

one

This invention relates to a measurement technique.

The integrating current converter to the imimage following frequency is known, which contains an integrating capacitor connected in parallel to the discharge key and to one input of a voltage comparator, another input of which is connected to a reference voltage source, and an output to a switching device, a parallel-connected current generator and an auxiliary integrating a capacitor, as well as an auxiliary integrating capacitor switch. The control input of the switch is connected to the output of the switching device. The non-linearity of the conversion function introduced by the finite discharge time of the integrating capacitor is compensated by the use of a resistor connected between and the burning capacitor and comparator, and the delay device.

In order to obtain a linear conversion function, it is necessary to establish a certain ratio between the value of the compensating resistor and the duration of the pulse generated by the delay device. The latter circumstance requires performing: a special adjustment operation to linearize the conversion functions and reduces

manufacturability of the converter.

The use of this converter as a variable input integrator

current is difficult due to the sensitivity of the converter to the instantaneous value of this current.

The proposed converter differs from the known one in that, in order to increase the accuracy in operation, a separating diode and an auxiliary voltage source are introduced into it. Moreover, the separation diode is connected between the point of connection of the current generator with the auxiliary integrating capacitor and the connection point of the integrating capacitor with the discharge key and the input of the comparator, and the auxiliary voltage source is connected in series with the auxiliary integrating capacitor

via auxiliary integrator capacitor switch.

The drawing shows a block diagram of the proposed Converter. The converter contains a generator /

a current made, for example, in the form of a compound transistor or amplifier with deep negative current feedback; main integrating capacitor 2; comparator 3 voltage, one input of which

attached to the main integrator

the capacitor, and the other to the source 4 of the reference voltage; and switching device 5, made, for example, in the form of a trigger or relaxation generator. The input of the latter is connected to a voltage comparator, and the output controls a switch 6 of the main integrating capacitor 2 n with a switch 7 of the auxiliary integrating capacitor 8, which is connected to the connection point of the generator / current and a separation diode 9 connected between the current generator and the main integrated circuit. a capacitor. One fixed contact of the switch 7 is connected to the auxiliary voltage source 10, and the other to the common point of the converter, the switch contact being connected to the auxiliary integrating capacitor 8.

The polarity of the auxiliary voltage source corresponds to the polarity of the isolation diode 9, which is locked if the auxiliary integrating capacitor is connected by a switch to the auxiliary voltage source.

The Converter operates as follows.

During the time interval, called the charging cycle, the switching device 5 sets the state of the switch 7, at which the auxiliary capacitor 8 is connected to the common point of the converter, and the open state of the key 6. In this case, the generator / current charges the parallel connected main 2 and auxiliary 8 integrating capacitors. The pairing at one input of the comparator 3 rises to the level of the reference voltage specified by source A. At the end of the charge cycle, the comparator outputs an IMpuls. This pulse sets the state of the switching device in which the switch 6 closes the discharge circuit of the main integrating capacitor, and the switch 7 connects the auxiliary integrating capacitor to the source 10 of the auxiliary voltage. According to the mutual polarity of the isolation diode 9 and the auxiliary voltage source, the isolation diode is locked by the voltage of the auxiliary voltage source during a time interval called the "discharge cycle."

During the discharge cycle, the current generator charges the auxiliary integrating capacitor, and the main integrated capacitor discharges through the switch 6. At the end of the discharge cycle, the switching device takes the initial state corresponding to the charging cycle. The duration of the discharge stroke is set either by the comparator 3 on the basis of decreasing the voltage on the main integrating capacitor to the level of reverse comparing, or by a self-switching device. After reverse switching, the state of the converter corresponds to the charge cycle. In this case, the voltage on the auxiliary capacitor is changed back by the voltage of the auxiliary voltage source, which unlocks the isolation diode. The charge accumulated during the discharge cycle in the auxiliary capacitor is distributed between the auxiliary and main capacitors and is taken into account in the form of the initial charge in the next discharge cycle.

The subject is inventive

An integrating current-to-pulse frequency converter containing an integrating capacitor connected in parallel to the discharge switch and to one input of a voltage comparator, the other input of which is connected to a reference voltage source, and an output to a switching device, connected in parallel to a current generator and an auxiliary integrated capacitor as well as a switch of an auxiliary integrating capacitor, the control input of which is connected to the output of a switching device, characterized in that Then, in order to improve the accuracy of the converter operation, a separation diode and an auxiliary voltage source are introduced into it, the separation diode being connected between the connection point of the current generator with the auxiliary integrating capacitor and the connection point of the integrating capacitor with the discharge key and the comparator input It is connected in series with an auxiliary integrating capacitor through a switch of an auxiliary integrating capacitor.