KR970000819B1 - Digital pcb crosstalk tester using monostable pulse latch - Google Patents

Abstract

A crosstalk test apparatus of digital PCB is provided that rapidly checks a reason of crosstalk in PCB pattern using a monostable pulse latch when an error occurs due to crosstalk. The crosstalk test apparatus of digital PCB using a monostable pulse latch for testing a crosstalk between interconnections in designing PCB includes a signal generator(10) being connected to a pin hole or via hole of a PCB to be tested by a signal transmitting bar(40) and a wire, for generating a monostable pulse signal(ST) under the control of a control signal; a plurality of crosstalk detectors(20A~20N) for detecting whether the signal inputted from the interconnections to which a plurality of crosstalk receiving bars(50A~50N) each connected via the wire is a crosstalk signal beyond a predetermined limitation value; and a display means(30) for receiving a test signal outputted from the plurality of crosstalk detectors(20A~20N) and displaying crosstalk receiving bars that received a crosstalk beyond the predetermined threshold value and its polarity.

Description

Crosstalk Tester of Digital PCB Using Monostable Pulse Latch

1 is an exemplary view for explaining a conventional inspection method for searching the PCB wiring that crosstalk occurs.

2 is a block diagram of a crosstalk test apparatus according to the present invention.

3 is an internal block diagram of the crosstalk detection module 20A to 20N shown in FIG.

4 is a diagram illustrating an inspection process using a crosstalk test apparatus according to the present invention.

5 is a diagram illustrating pulse timing of a crosstalk signal having a positive polarity.

6 is a diagram illustrating pulse timing of a crosstalk signal having a negative polarity.

7 is an illustration of a display module using an LED as a display element.

* Explanation of symbols for main parts of the drawings

10: Signal generating module 20A to 20N: Crosstalk detection module

21: amplifier 22, 23: monostable pulse generator

24, 25: latch portion 30: display module

40: Signal transmitting rod 50A to 50N: Crosstalk receiving rod

60: ground terminal

The present invention relates to a crosstalk test apparatus of a PCB for checking a crosstalk state between wirings when designing a PCB used as a board of a digital circuit. In particular, a crosstalk occurs when a digital PCB design causes malfunctions due to crosstalk. The present invention relates to a crosstalk testing apparatus for digital PCB using a monostable pulse latch signal to quickly detect a PCB pattern that causes the problem.

In general, crosstalks generated in digital circuits are classified into far-end crosstalk and near-end crosstalk. In general, near-end crosstalk appears in a waveform and phase similar to an input signal, and far-end crosstalk appears as an impulse with a short duration. The following is a brief description of fabric crosstalk that occurs frequently on digital PCBs.

The polarity of the far-end crosstalk is expressed as follows when its own impedance Ls, its own capacitance Cs, its mutual capacitance Cm, and its mutual impedance Lm are as follows.

(Cm / Cs) (Lm / Ls): Same polarity as input signal

(Cm / Cs) (Lm / Ls): Polarity opposite to input signal

In particular, a general microstrip PCB, which is widely used in industry, has a polarity opposite to an input signal, that is, a general crosstalk crosstalk phenomenon of (Cm / Cs) (Lm / Ls) occurs.

Referring to FIG. 1 attached to a conventional inspection method for searching for PCB wiring in which crosstalk occurs as described above, a signal generator is used at one end of the wiring that is an inspection target among the wirings of the PCB to be inspected. It is a tracking method that injects a signal and measures the level of the received (crosstalk) signal with a measuring instrument (oscilloscope, spectroscope, etc.) to track the crosstalk occurrence wiring of each individual wiring.

However, such a conventional method is very difficult to predict or inspect crosstalk cause lines and crosstalk lines because the wiring and stacking structure of the PCB substrate is very complicated in the case of multilayer PCBs, which are mainly used. In particular, due to crosstalk of digital circuits, Since the fault is generated only when the signal level is out of a certain limit, the conventional search method requires checking whether the measured signal level is out of the limit. Therefore, the work efficiency is low and the reliability of the test is low. Occurred.

An object of the present invention for solving the above problems is to replace the conventional signal generator with a monostable pulse generator triggered by the switch, the instrument is a Schmitt trigger to quickly determine whether the crosstalk is beyond the preset threshold Replace with the included monostable pulse generator and use the monostable pulse latch to enable crosstalk test for multiple wires simultaneously by integrating the signal generator and the instrument while adopting a plurality of crosstalk detection modules embedded therein. To provide a crosstalk test device for digital PCB.

A feature of the present invention for achieving the above object is, in the cross-talk test device of the PCB for checking the cross-talk state between the wiring during the PCB design, the signal transmission rod and wire for directly transmitting a pulse signal to the pinhole or via hole of the PCB to be inspected Signal generation means for generating monostable pulse signal by a control signal and a signal input from a wire to which a plurality of crosstalk receiving rods individually connected through a wire are connected may be a crosstalk signal exceeding a preset limit. And a display means for receiving a plurality of crosstalk detection means for determining a crosstalk, and a crosstalk receiving rod that receives a crosstalk signal output from the plurality of crosstalk detection means and displays a crosstalk having received a crosstalk exceeding a preset threshold and the nature (polarity) of the crosstalk. It is included.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a block diagram of a crosstalk test apparatus according to the present invention, and is connected to a signal transmitting rod 40 and a wire for directly transmitting a pulse signal to a pin hole or a via hole of a PCB to be inspected. Signal input from the signal generation module 10 capable of generating the monostable pulse signal ST by the control signal and the wiring to which the plurality of crosstalk receiving rods 50A to 50N, which are individually connected via wires, are connected. Receives a test signal output from the plurality of crosstalk detection modules 20A to 20N and the plurality of crosstalk detection modules 20A to 20N to determine whether crosstalk signals exceed a preset threshold value and exceed a preset threshold. Crosstalk is composed of a crosstalk receiving rod and the display module 30 for displaying the nature (polarity) of the crosstalk.

In addition, the crosstalk test apparatus according to the present invention includes a ground terminal 60 connected to the object under test to form an electrical return path of the measurement signal.

In addition, the signal generation module 10 is configured to externally set the voltage and the duration of the pulse when generating the monostable pulse signal (ST), the pulse by the push signal (SW1) of the signal generation operation control switch Means were triggered to generate.

In addition, the crosstalk detection module 20A to 20N is set when the signal Sc indicating the crosstalk signal is greater than or equal to a set threshold value, and has means for resetting by the crosstalk signal SW2 of the operation control switch. It was.

The internal block structure of the crosstalk detection module 20A to 20N is as shown in FIG. 3 of the accompanying drawings, and includes a first single-stable pulse generator 22 triggered by a crosstalk voltage of positive phase. And amplifies the second single-stable pulse generator 23 triggered by cross-talk voltage of the negative phase and the cross-talk signal Sc detected by the cross-talk detection rods 50A to 50N for easy handling. The amplifier 21 for supplying the trigger input of the first and second stage stable pulse generators 22 and 23 and the signals Pon and Pof output from the first and second stage stable pulse generators 22 and 23 are provided. Each of the first and second latches 24 and 25 is configured to hold a latch operation when the input signal is pressed by the push signal SW2 of the operation control switch.

In addition, the first and second stage stable pulse generators 22 and 23 are both configured to externally set the trigger voltage level, and the Schmitt trigger and the monostable pulse generator are combined.

In addition, in the polarity of the trigger voltage, the first single-stable pulse generator 22 is set to a positive voltage, and the second single-stable pulse generator 23 is set to a negative voltage. Output stable pulses respectively.

In addition, the output signal of the first latch unit 24 denoted as Sdn among the signals output from the crosstalk detection modules 20A to 20N is in phase in response to the output signal St of the signal generation module 10. It is a signal for notifying when a crosstalk greater than or equal to the threshold set in, and the output signal of the second latch unit 25 denoted by Sdf is a signal indicating that the cross-talk signal of the opposite phase is introduced (Figs. 3 and 4). Sd signal is the name of the signal in which Sdn and Sdf are not distinguished.

Referring to the accompanying drawings, preferred embodiments of the crosstalk test apparatus according to the present invention configured as described above are described in detail as follows.

4 is a diagram illustrating an inspection process using a crosstalk test apparatus according to the present invention. FIG. 5 is a diagram illustrating pulse timing of a crosstalk signal having a positive polarity, and FIG. 6 is a pulse timing of a crosstalk signal having a negative polarity. It is an illustration.

As shown in FIG. 4 of the accompanying drawings, the signal transmitting rod 40 of the crosstalk test apparatus according to the present invention is connected to the PCB crosstalk caustic wiring in which the component is not mounted, and the crosstalk receiving rod 50 is connected to the estimated crosstalk. ).

After that, the signal SW1 is generated by pressing the first switch, which is a switch for controlling the signal generation operation.

The signal SW1 generated by the first switch outputs a monostable pulse having a predetermined duration from the signal generation module 10 shown in FIG. 2 and inputs it as a crosstalk signal through interference between PCB wires. do.

At this time, since the crosstalk state may have a positive polarity and a negative polarity, it will be described with reference to FIG. 5 from the case of having a positive polarity.

The left side of FIG. 5 is an example of waveforms when a crosstalk signal Sc that is larger than the trigger set value Ps of the monostable pulse generator 22 of FIG. 3 is introduced, and the right side is smaller than the trigger set value Ps. A small crosstalk signal Sc is introduced.

When a crosstalk signal Sc having a positive polarity greater than the set value Ps is introduced, the first single-stable pulse generator 22 is triggered and output as a single-stable pulse having a predetermined width tpo as a duration ( The left side Pon of FIG. 5) is latched by the first latch unit 24 to output the set state (see left Sdn of FIG. 5).

On the other hand, when the crosstalk signal Sc having a positive polarity smaller than the set value Ps is introduced, since no pulse is generated, the first latch unit 24 maintains the reset state (see right Sdn in FIG. 5). ).

Referring to FIG. 6 with the case of having a negative polarity unlike in the case described above, the left side of FIG. 6 is a trigger set value (Ps: negative voltage value) of the monostable pulse generator 22 of FIG. A waveform example is shown when a lower crosstalk signal Sc is stronger, and the right side shows a case where a crosstalk signal Sc is weaker than the negative trigger set value Ps. When the crosstalk signal Sc having a negative polarity lower than the set value Ps is introduced, the second single-stable pulse generator 23 is triggered and output as a single-stable pulse having a predetermined width tpo as a duration ( The left side Pon of FIG. 6) is latched by the second latch portion 25 to output the set state (see Left Sdn of FIG. 6).

On the other hand, when a crosstalk signal Sc having a negative polarity greater than the negative set value Ps is introduced, a pulse does not occur, and thus the second latch unit 25 maintains a reset state (right side of FIG. 6). Sdn).

Thereafter, the latch signals Sdn and Sdf output from the first and second latch units 24 and 25 are supplied to the display module 30 to display the position of the crosstalk generation wiring and the nature of the crosstalk.

When the inspection operation as described above is pigmented once and the inspection is to be performed again, the first and second latch portions 24 and 25 are reset by pressing the second switch shown in FIG. 4 to return to the initial mode. .

FIG. 7 is an exemplary view of the display module 30, in which an LED is used as a display element, and an example in which six crosstalk detection modules 20 are provided.

The vertical number refers to the number of the receiving rods for which the crosstalk was received, and the 'normal phase' indicates that the nature of the crosstalk occurred is near-end crosstalk or the high frequency odd mode propagation speed is the even mode propagation speed. Reverse crosstalk in a much faster PCB structure (Cm / CsLm / Ls: special case), whereas 'out of phase' means that the high-frequency odd mode propagation rate is slower than the even mode propagation rate. It means a cross-talk cross-section in PCB structure (Cm / CsLm / Ls: general case).

Crosstalk cause line, crosstalk line, and crosstalk of a digital PCB crosstalk test apparatus using a monostable pulse latch according to the present invention operating as described above causing crosstalk levels that cause malfunctions in a PCB of a complex digital circuit exceeding a certain threshold As it is possible to quickly identify the rough nature of the crosstalk test, the efficiency of work is increased and the reliability of the test can be increased.

Claims (5)

In the PCB cross-talk test apparatus to check the cross-talk state between wirings when designing the PCB, it is connected to the signal transmitting rod and wire for directly transmitting the pulse signal to the pinhole or via hole of the PCB to be inspected, and the monostable pulse signal is Signal generating means capable of generating; A plurality of crosstalk detection means for discriminating whether a signal input from a wire to which a plurality of crosstalk receiving rods individually connected through a wire is a crosstalk signal exceeding a preset limit value; And a display means for receiving a test signal output from the plurality of crosstalk detection means and displaying a crosstalk receiving rod having a crosstalk exceeding a preset threshold and a character (polarity) of the crosstalk. Crosstalk tester for digital PCB using pulse latch. The method of claim 1, wherein the signal generating means is capable of externally setting the voltage and duration of the pulse when generating the monostable pulse signal, wherein pulse generation is triggered by the signal generation control signal. Crosstalk tester for digital PCB using stable pulse latch. 2. The apparatus of claim 1, wherein the crosstalk detecting means comprises: a first single-stable pulse generator triggered by a crosstalk voltage of a positive phase; A second single-stable pulse generator triggered by a crosstalk voltage in reverse phase; And a first and second latch unit for receiving the signals output from the first and second stage stable pulse generators, respectively, and maintaining the latch operation at the time point at which the latch operation control signal is input. Crosstalk tester of used digital PCB. 4. The monostable pulse latch according to claim 3, wherein the first and second single-stable pulse generators are configured to externally set the trigger voltage level, and the Schmitt trigger and the monostable pulse generator are combined. Crosstalk Tester of Digital PCB. 4. The monostable pulse latch of claim 3, wherein the first single stable pulse generator and the second single stable pulse generator are configured to cause crosstalk stronger than a set value to be triggered for crosstalk signals having opposite voltage polarities. Crosstalk Tester of Digital PCB.