RU1827652C - Device for contactless diagnosis of logical states of digital integrated circuits - Google Patents

Abstract

Usage: in instrumentation. The inventive device comprises a proximity electromagnetic sensor 1, a broadband amplifier 2, pulse shapers 3, 4, 5, an adder 6, a ban element 7, a fourth pulse shaper 8, an RS-trigger 9. The device provides a non-contact determination of the logical state at the monitored output of the CIS without compromising the protective coating of live parts of a typical replacement element. 8 ill.

Description

The invention relates to a measurement and control technique and can be used in digital integrated circuit (CIS) control devices and allows to expand the functionality.

The aim of the invention is to expand the functionality by taking into account the shape of the transient process of the output voltage of the circuit when switching from one logical state to another.

The invention is illustrated in Fig. 1, which shows a circuit diagram of a device for contactless diagnosis of logical states of digital integrated circuits; in FIG. 2 are timing diagrams illustrating the operation of the device.

The device comprises a non-contact electromagnetic sensor 1, a broadband amplifier 2, a first pulse shaper 3, a second pulse shaper 4. a third pulse shaper 5. adder 6, a prohibition element 7,

fourth pulse shaper 8. RS-trigger 9.

A shock excitation circuit comprising one or more turns of an inductor and inter-turn capacitance is used as a non-contact electromagnetic sensor.

The design of the sensor is shown in Fig. 3, where the following designations are introduced: 10 — metal plate; 11 - contact area, 12 - insulating material: 13 - location of the output of the CIS; 14 - inter-turn connections; 15, 16 are the connection points of the signal and the housing, of the coaxial cable, respectively.

Fig. 3 shows a sensor consisting of 3 series-connected self-closing coils with inter-turn connections.

An equivalent diagram of the design of the sensor is presented in figure 4 where the following notation is introduced - equivalent

with

the total inductance of the sensor and coaxial; Ck is the equivalent capacitance of the circuit, consisting of the inter-turn capacitance of the sensor and the insertion capacity of the cable; M is the mutual induction between the output of the CIS and the inductance of the sensor; Sowing the communication capacitance between the digital output terminal and the sensor structure; R is the active resistance of the circuit, determining its quality factor.

A schematic representation of the sensor is shown in Fig.5. This design of the sensor is selected on the basis of obtaining the highest communication capacitance Sev and, consequently, better excitation of the shock excitation circuit, as well as increasing the noise immunity of the sensor which is ensured by the fulfillment of the condition:

steam

(1) where Spar is the parasitic capacitance of communication with other current-carrying lines.

The arrangement of the sensor relative to the adjacent terminals of the monitored digital relay is shown in Fig.6, where the following notation is introduced:

Echpar — parasitic electric field strength 1;

§2pair - parasitic electric field strength 2;

E is the useful electric field strength;

Spar1 — parasitic coupling capacitance 1;

Spar2 is a parasitic coupling capacitance 2.

Consider the principle of the sensor on the example of control circuits of the 133 series. When a logical element transitions from a log state. 1, in the log. About (or vice versa), the voltage at the monitored output of the CID changes from 0.2V to 3V (or vice versa) during the switching time, which for the CMS 133 series is 25 ns. In this case, due to the coupling capacitance, the shock excitation circuit is formed, which is formed by the elements Sk, Lk, R at the resonant frequency

 2 VUCK- (2)

In addition, when current flows through the CSC terminal due to mutual induction M, the circuit is excited, as well as due to the emission of electromagnetic energy by the CSC terminal. A voltage jump of 0.2 V to 3 V in duration does not have a spectrum width of the order of

I tf

1

25-10 9 s

40 MHz

(3)

The combination of all these 3 factors leads to shock excitation of the circuit, the physical processes in which are aperiodic oscillations (due to

the influence of R), the form of which is shown in Fig. 7, where the following notation is introduced: Qcis voltage at the output of the CIS; Beat - voltage at the output of the sensor; t is time; C, t2 - time points corresponding to the beginning

forming leading and trailing edges of the pulse of the output voltage of the CIS; respectively.

By analyzing the type of aperiodic oscillations of the circuit, it is also possible to unambiguously determine the direction of the transition of the CIS logic element from 0.2V to 3.0V (time ti) or from 3.0 to 0.2V (time t2), because processes during transitions are of an antiphase nature. The amplitude characteristics of the oscillations are not symmetrical, since the switching times from log, 1 to log, 0 and vice versa are different, and also because of the asymmetric connection of the coaxial to the circuit.

When conducting the experiment on the logical element 2I-NOT (CIS 133LAZ), the sensor was three turns of PEV-2 00.21 wire around the output of the CIS. The measurements were carried out using an oscilloscope.

C1-99 with RK-75 coaxial cable and an output resistance of 1 mOhm. Plots of the voltages taken from the oscilloscope are shown in the photograph (Fig. 8), where the sweep A corresponds to the pulse at the output of the 2INE element, and sweep B is the signal taken from the sensor.

The choice of a sensor consisting of 3 turns is explained by a compromise between the complexity of the sensor design and the natural resonant frequency of the circuit, because an increase in the number of turns leads to an increase, increase in CK and, consequently, to a decrease in the resonant frequency fpS3 and a decrease in the requirements for broadband

and the speed of subsequent devices. The oscillation process of the shock excitation circuit can be damped if necessary by introducing an active resistance or by reducing the value of the load resistance. In the future, we will consider a deeply damped oscillatory process.

The output of the electromagnetic sensor 1 is the input of a broadband amplifier 2, the output of which is connected to the input of three pulse shapers 3, 4, 5, the output of the first pulse shaper 3 and the output of the second pulse shaper 4 are connected to the input of the adder 6, the output of which and the output of the third pulse shaper 5 are are the input of the inhibit element 7, the output of which is connected to the input of the fourth pulse shaper 8, the first output of which is connected to the S-input of the RS-trigger 9, the second output of the fourth pulse shaper 8 is connected and with the R-input of the RS-flip-flop 9, the direct output of which 10 is the output of the device. The operation of the non-contact diagnosis of logical states of digital integrated circuits is illustrated in Fig. 2.

If, in the initial state, the CIS output is at a high level, at the time ti, a transition to the low state UBX occurs, this transient produces shock excitation of the sensor, in which the transient shock excitation (U) takes place. The voltage induced in the sensor 1 is amplified by a broadband amplifier 2 and applied to the inputs of three pulse generators 3, 4, 5. The first pulse shaper 3, when the operating voltage is reached at its input (threshold 1), produces a pulse with a delay of rz of duration t. The pulse duration is selected from the condition

Tk + r. Tmin / 2,

(4)

where Tmin is the smallest possible pulse width for a device in which the DSC is used (if1). For the second pulse shaper 4, the trigger threshold is a negative voltage (threshold 2) and it can be triggered when the Q-factor of the shock excitation circuit is high, along the second negative half-wave of the loop. In this case, at the output of the second driver 4, a pulse of the same duration (selected from the same conditions), in negative polarity, is also generated. In this case, bipolar pulses arrive at adder 6, the leading edges of which are shifted by a time equal to the half-period of the oscillations of the shock excitation circuit. At the output of adder 6, two short, bipolar pulses are shifted by time t. The third driver 5 is triggered at the same time as the first driver 3, but generates a pulse delayed by 1z2 (11fz). The time tz2 and TB are selected from the condition that the second pulse of the adder 6 is reliably covered for its blanking. The pulses from the output of the adder b and the third driver 5 are supplied to the corresponding inputs of the prohibition element,

where is the blanking of the second counting pulses of the output of the adder 6 (Uc).

The pulses from the output of the inhibit element 7 are fed to the fourth pulse shaper 8, which, depending on the polarity of the pulses at the output of the CIS, generates pulses of positive polarity at the first or second output, respectively (, (1) f42). Duration

pulse is selected from the condition

Tsr T4

Tmin

(5)

where tcp is the minimum possible pulse duration at which the logic element reliably operates.

The pulses from the output of the fourth driver are supplied to the corresponding

the inputs of the RS-trigger 9. The output of the RS-trigger 9 repeats the state of the output of the monitored digital circuit with a certain delay in time t3, due to the delay in the operation of the first pulse shaper 2 (or 3), the fourth pulse shaper 8 and RS-trigger 9. The pulse from the first The driver output sets the RS trigger 9 to 1 state (). The processes taking place in the device, when

the transition of the voltage at the output of the CIS from a low level to a high is similar.

Thus, the device provides a non-contact determination of the logical state at a controlled output of the CIS without

violation of the protective coating (varnish) of the live parts of a typical replacement element, which indicates the expansion of the functionality of the device.

Feasibility

achieved through the use of an inventive device having greater functionality than the prototype.

Claims (1)

The claims A device for non-contact diagnosis of logical states of digital integrated circuits, including a non-contact electromagnetic sensor, output which is the input of a broadband amplifier, characterized in that, in order to expand the functionality by taking into account the shape of the transient process of the output voltage of the circuit upon transition from one logical state to another, three pulse shapers are introduced into it, the inputs of which are connected to the output of a broadband amplifier, an adder, the input of which is the outputs of the first and second pulse shapers, the outputs of the adder and the third pulse shaper are connected to the input of the inhibit element, the output of which is connected to the input of the fourth pulse shaper, the first output which is connected to the S-input of the RS-flip-flop, the second output of the fourth pulse former is connected to the R-input of the RS-flip-flop, the direct output of which is the output of the device. FIG. I / s FMGZ F // G7 5 Ccf m t twC FNG. tf Sg.G.Ј w. hp / x / Og. 5 FIG. 6 C% bg. 7 ., V