SU978054A1 - Quasi-balanced bridge for separate measuring one of non-resonance three element two-terminal network parameters - Google Patents

Description

The invention relates to electrical measuring equipment, in particular to measuring parameters of passive complex values, and can be used to monitor and measure parameters of objects, for example, in electrochemistry and biology to study the nature of electrochemical and biological systems, in microelectronics chemical industry for cont. the role of various technological processes.

The four-shouldered, balanced AC bridge is known, which consists of a four-shoulder bridge containing the object to be measured, a reference arm composed of resistance stores and a store, bones, and auxiliary shoulders, a sweeping frequency generator, and an U1 oscilloscope.

The disadvantage of the bridge is the complexity and considerable duration of the process of bringing the gauge bridge to an equilibrium state due to the presence of three interconnected adjustments. In addition, in measurement practice often arises in favor. measuring only one infrared:

the object's mathematical parameter (two-terminal), while the other two parameters are non-informative and complicate the measurement process. in this case, the indicated bridge must be balanced by non-informative parameters and thus spend extra time on the measurement.

The closest technical solution to the present invention is a meter of frequency characteristics of complex two-terminal networks, which allows measuring one parameter of a three-element two-terminal network independently of the other two. The meter consists of two sinusoidal oscillators, one switch and three switches, three inductive voltage dividers, two amplifiers, an adder, a phase-sensitive detector, and a comparison unit C21.

The disadvantage of the meter is the complexity and duration of the measurement process of one of the three parameters of the monitored two-pole network, since to measure one parameter, the meter must be brought to two states, i.e. achieve equal signal modules twice. In addition, the meter has low accuracy, since the measured parameter is determined through the transfer coefficients of two voltage dividers and two amplifiers. The purpose of the invention is to accelerate and simplify the balancing process. The goal is achieved by the fact that in a quasi-balanced bridge for separate measurement of one of the parameters of nonresonant three-element two-terminal, containing two sine-wave oscillators, two keys, a switch and a comparator unit, the sinusoidal oscillators are connected to a switch, a four-arm chain consisting of three single elements is inserted , one of which is adjustable, and the investigated non-resonant three-element two-terminal network, subtraction unit, variable sig converter a, a integrator, a phase shifter, a square pulse shaper, first and second control units, a reference pulse generator, a reversible counter and an equilibrium block, and shivani, the measuring diagonal of the four-shouldered bridge circuit connected to the first and second inputs of the subtraction unit, one of the vertices of the measuring diagonal of the four shoulders of the chain are connected to the first input of the first key, and the output. The calculator is connected via an alternating signal converter to a constant with the second input of the first key, the output of the latter through an integrator and a comparison unit is connected to one of the inputs of the first control unit, while the third input of the control unit is connected through a square pulse shaper and phase shifter with the output of the subtraction unit, the outputs of the first control unit are connected respectively to the first and second keys, and the reference pulse generator is connected via a key and a switch to a reversible counter, the output cat The op is connected to the balancing unit, and the outputs of the second control unit are connected to the control inputs of the switch, switch, and reversible counter, with one of the vertices of the titanium diagonal four-shouldered connected to the switch and the other to the common bus. The entirety of the above features enables a simple and quick process of balancing a bridge measuring circuit. Balancing occurs with the help of one balance circuit and independently, independently of the other two, in this case non-informative, parameters of a controlled three-element two-port network. The measurement of one of the parameters of the monitored two-pole takes place with high accuracy, since 6 the basis is the bridge measurement method. FIG. 1. given a functional electrical circuit of a quasi-balanced bridge; in fig. 2-4 are examples of the construction of four-shoulder bridge chains when measuring the parameters of the studied two-terminal networks with various replacement schemes. The quasi-balanced bridge contains (Fig. 1) a four-arm bridge circuit connected to the generators 1 and 2 of sinusoidal oscillations by means of the switch 3, the four-arm circuit includes exemplary resistors 4 and 5, the adjustable exemplary resistor b and the two-port circuit being investigated, consisting of resistors 8 and 9 and the capacitor 10. In addition, the quasi-balanced bridge comprises a subtraction unit 11, an alternating -Signal converter 12, an inverter 13, a comparison unit 14, a key 15, a phase shifter 16, a former 17 square pulse generator Control unit 18, reference pulse generator 19, key 20, switch 21, reversible counter 22, second control unit 23, and balance unit 24. All nodes of the quasi-balanced bridge are made on serial analog and digital equipment. The device works as follows. On command from the second control unit 23, the generator 1 of sinusoidal oscillations is connected to the four arms of the circuit using the switch 3 and the generator 2 is disconnected. After the oscillations have been established, the key 15 and the alternating voltage directly through this key are opened by a command from the first control unit 18 begins to flow to the integrator 13, which integrates the variable voltage applied to it. After the time specified by the half period of oscillations coming from the driver 17, the control unit 18 issues a command to the key 15 to stop the supply of alternating voltage to the integrator 13 and connects to the integrator 13 via the switch 15 a constant voltage removed from the output of the converter 12k. This voltage is integrated, as a result of which the integrator is discharged, and at the moment when the voltage at the output of the integrator 13 reaches zero, the comparison unit 14 is triggered, according to its command using the block 18 and the key and 15 the constant voltage deviates from the input of the integrator 13. The discharge time of the nocTOHHHiiiM voltage is fixed by the block 18 in the form of a rectangular impulse coming from block 18 to the key 20, the key 20 is opened for the duration of this rectangular impulse and pulses From generator 19, through switch 20 and switch 21, they are fed to the direct input of the reversible counter 22. Next, the second control unit 23 uses switch 3 to connect a sinusoidal oscillator 2 to the four arms of the circuit and turn off generator 1.

Subsequently, after the transition process has been established in the four arms of the chain, the whole process repeats again with the only difference that the block 23 translates the switch 21 into another position, and the pulses from the reference generator 19 do not go to the forward, but to the reverse input the counter 22. As a result of these two clocks, a certain number remains on the counter 22, and the counter 22 is executed with an indication of the sign of this number. Then, at the command of the control unit 23, the number obtained on the counter 22 is taken into account and taken to the balance unit 24, which can be executed either as a stepper motor or as a digital summing unit. The balancing unit 24 adjusts the resistance of the reference resistor 6 until it reaches a quasi-equilibrium state, in which, after every two cycles of connecting the generators 1 and 2 to the quadrilateral circuit, a number equal to zero is fixed on the reversing counter 22. In this case, one of the measured parameters, in this example, the resistance of the resistor 8, a three-element two-terminal network, is measured 7 times integrally by the reference resistor 6. In this case, the bridge quasi-equilibrium does not depend on the other two, in this case uninformative parameters of the resistor 9 and the capacitor 10, included in the controlled three-element two-port 7. Since the integration of alternating voltage occurs during a time equal to half the period of the sinusoidal voltage, then each two cycles, after which The control action takes place over a time slightly longer than the maximum period of the generators 1 and 2. All this makes it possible to significantly speed up the process of balancing the measuring bridge

chains.

Quasi-Balanced Host Allow

do not measure separately

different parameters of three-element two-terminal systems with various replacement schemes.

FIG. 2 shows examples of raschtic three-element two-terminal networks.

with different replacement schemes. The three other shoulders of the four-shoulders of the bridge chain include identical elements. In principle, any of these exemplary elements 4.5 and 6, made in the form of either resistors or capacitors, or inductors, is adjustable. In the state of quasi-equilibrium, the resistance of resistor 25 (Fig. 2), capacitance 26 (Fig. 3), inductance of the inductance coil 27 (Fig. 4) can be measured separately.

The proposed device is practically tested. Determined raylich20

Parameters of a three-element two-terminal network with various layouts. The bridge was powered by two generators with frequencies of 1 kHz and 7 kHz. As an adjustable element

25 used digital control resistance. The time of the initial reduction of the bridge to the state of quasi-equilibrium in the automatic mode did not exceed 4.2 Tc. The change in the wide limits of the two other parasitic parameters of the controlled two-pole device had practically no effect on the state of quasi-equilibrium.

Proposed balanced bridge

35 may be used to measure pairs of apertures of semiconductor structures in the manufacture of large integrated circuits. Measurements allow you to adjust and control the process and thereby affect the output chip yield.

Claims (2)

Invention Formula 45 Quasi-balanced bridge for the separate measurement of one of the parameters of non-resonant three-element two-terminal, containing two sinusoidal oscillators, two keys, a switch and a comparison unit, sinusoidal oscillators are connected to a switch, characterized in that, in order to speed up and simplify the balancing procedure, a four-arm chain consisting of three elements of the same type is inserted into it, of which is adjustable, and investigated nonresonant three-element two-terminal device, subtraction unit, variable-to-constant signal converter, integrator, phase shifter, driver rectangular impulses first and the second control unit, the reference pulse generator, the reversible counter and the balance unit, the measuring diagonal of the four-shouldered circuit connected to the first and second inputs of the subtraction unit, one of the vertices of the measuring diagonal of the four-shoulder circuit is connected to the first input of the first key, and the output of the subtraction unit is connected through the alternator signal to a constant with the second input of the first key, the output of the latter through the integrator and the comparison unit is connected to one of the inputs; the first control unit, while the second input of the control unit is connected through the square pulse shaper and the phase shifter to the output of the subtraction unit, the outputs of the first the control unit is connected to the first and second keys, respectively, the reference pulse generator is connected via a key and a switch to a reversible counter, the output of which is connected to the balance unit, and the outputs of the second control unit are connected to the control inputs of the switch, switch and reversible counter, one from the vertices of the power diagonal is connected to the switch, and the friend to the common bus. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 158627, cl. Q 01 R 17/10, 1962. 2. USSR author's certificate No. 530273, class, G 01 R 27/28, 1975 (prototype). I x (rig 2