WO2013132298A1

WO2013132298A1 - Electrical measurement device

Info

Publication number: WO2013132298A1
Application number: PCT/IB2012/054917
Authority: WO
Inventors: Varun Aggarwal; Gaurav Gandhi
Original assignee: Varun Aggarwal; Gaurav Gandhi
Priority date: 2012-03-04
Filing date: 2012-09-17
Publication date: 2013-09-12

Abstract

An electrical measurement device for capturing and measuring electrical signals such as an improved oscilloscope and a user interface for displaying the two or more electrical signal representations simultaneously is provided. The electrical measurement device includes an input module coupled to a device under test (DUT), where the input module is configured to receive one or more electrical signals from the DUT. The electrical measurement device also includes a processor module for processing the one or more electrical signals and to calculate a plurality of characteristics for the one or more electrical signals. Further, the electrical measurement device includes an output module configured to generate two or more electrical signal representations based on the plurality of characteristics.

Description

ELECTRICAL MEASUREMENT DEVICE

TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates generally to electrical measurement devices useful for measuring characteristics of electrical signals and more specifically to oscilloscopes. BACKGROUND

[0002] An oscilloscope is a type of electronic/electrical test instrument that allows observation of shape of electrical signals as constantly varying signal voltages, usually as a two-dimensional graph of one or more electrical potential differences using the vertical or Ύ axis, plotted as a function of time, (horizontal or V axis). The graph, usually called the trace, is drawn by a beam of electrons striking the phosphor coating of the screen making it emit light. Although an oscilloscope displays voltage on its vertical axis, any other quantity that can be converted to a voltage can be displayed as well. In most instances, oscilloscopes show events that repeat with either no change, or change slowly. Oscilloscopes are commonly used to observe the exact wave shape of an electrical signal. In addition to the amplitude of the signal, an oscilloscope can show distortion, the time between two events (such as pulse width, period, or rise time) and relative timing of two related signals.

[0003] Oscilloscopes are used in the sciences, medicine, engineering, and telecommunications industry. As general-purpose instruments they are used for maintenance of electronic equipment and laboratory work. Special-purpose oscilloscopes may be used for such purposes as analyzing an automotive ignition system, or to display the waveform of the heartbeat as an electrocardiogram.

[0004] Traditionally, all oscilloscopes used cathode ray tubes as their display element and linear amplifiers for signal processing, (commonly referred to as CROs) however, modern oscilloscopes have LCD or LED screens, fast analog-to-digital converters and digital signal processors. Although not as commonplace, some oscilloscopes use storage CRTs to display single events for a limited time. Oscilloscope peripheral modules for general purpose laptop or desktop personal computers use the computer's display, allowing them to be used as test instruments. The current versions of oscilloscopes have the possibility of plotting curves representing signal voltage with respect to time and frequency. Standard oscilloscopes have the possibility of plotting only a given signal or signals with respect to time or frequency. Some of these also allow the option of plotting one signal with respect to another signal, also called Lissajous pattern. Some of the recent patents on oscilloscopes include US 8073656, 7589728, 7392508, 7373281. However, none of them has the possibility of plotting several Lissajous pattern or Lissajous patterns that are mathematical functions of the probed signals on a single screen.

OBJECTS OF THE INVENTION

[0005] The advent of memristors, resistive RAMs and other circuit elements showing non-linear behavior is changing the circuit theory and makes current oscilloscopes unable to cope up with analysis of emerging devices. From the standard Voltage/Current- Time and Voltage/Current-Frequency analysis, now the relationship between voltage-current and charge-flux is gaining prominence of these new circuit elements

[0006] Thus there is a need for improved oscilloscopes that can capture the non-linear behavior of memristors, resistive RAMs and devices incorporating these elements.

[0007] The principal object of the invention is to provide an electrical measurement device for capturing and measuring electrical signals in order to generate two or more electrical signal representations based on the plurality of characteristics of the signals emanating from a device under test (DUT).

[0008] Another object of the invention is to provide a method for generating the two or more electrical signal representations simultaneously that are representative of the signals emanating from a device under test (DUT).

SUMMARY OF THE INVENTION

[0009] In one aspect, the invention provides an electrical measurement device, for example an improved oscilloscope for capturing and measuring electrical signals. The electrical measurement device includes an input module coupled to a device under test (DUT) that is placed under observation for measuring electrical signals. The input module is configured to receive one or more electrical signals from the DUT. The electrical measurement device also includes a processor module for processing the one or more electrical signals and to calculate a plurality of characteristics for the one or more electrical signals; and an output module configured to generate two or more electrical signal representations based on the plurality of characteristics.

[0010] In another aspect, the invention provides a method for capturing and measuring electrical signals for a DUT. The method includes the steps for receiving one or more electrical signals from the DUT, processing the one or more electrical signals to calculate a plurality of characteristics for the one or more electrical signals, and generating two or more electrical signal representations based on the plurality of characteristics.

DRAWINGS

[0011] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0012] FIG. 1 is a block diagram representation of the electrical measurement device according to one aspect or the invention; [0013] FIG. 2 is a graphical representation of the stimulus signal with respect to time for DUT;

[0014] FIG. 3 is a graphical representation of the channel 2 signal with respect to time;

[0015] FIG. 4 is a graphical representation of the signals from channel 1 and channel 2;

[0016] FIG. 5 is a diagrammatic representation of an exemplary user interface flow for displaying the two or more electrical signal representations; and

[0017] FIG. 6 is a flowchart representation of a method for capturing and measuring electrical signals for a DUT according to one aspect of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] As used herein and in the claims, the singular forms "a," "an," and "the" include the plural reference unless the context clearly indicates otherwise. [0019] In one aspect, the current invention provides for an electrical measurement device such as an improved oscilloscope for capturing and measuring electrical signals in the form of plots of several Lissajous pattern and other patterns on a single screen wherein the horizontal axis of one Lissajous signal represents mathematical function on one channel while vertical axis of the same Lissajous signal represents mathematical function on another channel. Also, each axis can be mathematical function of inputs from both channels.

[0020] In another aspect, the invention provides a user interface for plotting several

Lissajous patterns for one or more input channels, and other different combinations of outputs that are mathematical functions corresponding to different input channels. [0021] Now turning to drawings, FIG. 1 is a block diagram representation of an electrical measurement device 10 that includes an input module 12 coupled to a device under test (DUT) 14 that is placed under observation for measuring one or more electrical signals, wherein the input module 12 is configured to receive one or more electrical signals 16 from the DUT 14. It would be appreciated by those skilled in the art that the one or more electrical signals are generated upon an application of a stimulus signal 26 on the DUT.

[0022] The electrical measurement device 10 further includes a processor module 18 for processing the electrical signals 16 and to calculate a plurality of characteristics for the electrical signals. It would be appreciated by those skilled in the art that the characteristics may be any one or more of the following- current, voltage, time, frequency, flux, charge, maximum current with each polarity, maximum voltage with each polarity, bifurcation parameter, lyapunov exponent, eigen- vectors, user-postulated state variable governing memristance, conductance and/or resistance.

[0023] In one example, the processor module is configured for processing the one or more electrical signals based on a user input. In another example, the processor module is configured for processing the one or more electrical signals based on a pre-defined selection made available to a user through the user interface.

[0024] The electrical measurement device 10 further includes an output module 20 configured to generate two or more electrical signal representations 22 based on the characteristics as described herein. It may be noted here that the two or more electrical signal representations are also referred herein as outputs, output representations, plots or graphs and each signal relates to a corresponding channel in the representations. In one exemplary embodiment, the two or more electrical signal representations comprise mathematical functions of one or more electrical signals. Few other non-limiting exemplary embodiments with different representations are provided below.

[0025] In one specific exemplary embodiment the invention provides an electrical measurement device for representing four Lissajous patterns each between voltage from: a) Channel 1 versus Channel 2, b) Time integral of voltage of channel 1 versus channel 2, c) Channel 1 versus integral of voltage of channel 2, and d) Time integral of voltage of channel 1 versus time integral of voltage of channel 2

[0026] Channel 1 and Channel 2 as referred herein are typically the input ports of the input module provided in the electrical measurement device to receive the electrical signals from the DUT. FIGS. 2-4 are exemplary graphical representations of the stimulus, channel 1 and channel 2 signals. FIG. 2 shows a graphical representation 30 for the stimulus signal against time. In a specific example the stimulus signal is a composite designed signal derived from different shaped signals, for example triangular shaped, in the form of rising and falling staircase of same or different frequency (same frequency has been used for trianglular signal of FIG. 2) but same amplitude. Such a composite designed signal is useful for finding the memristive characteristics of the DUT. It may be noted here that the graphical representation 30 may also be the signal output of channel 1 i.e the signal being tested from DUT. FIG. 3 is a graphical representation 32 for the channel 2 signal against time. FIG. 4 is a graphical representation 34 for channel 1 versus channel 2 as referred herein above.

[0027] In a more specific exemplary embodiment that has a memristor and other passive device as the DUT, the output of the electrical measurement device for includes representations relating to a) voltage-current curve, b) flux-current curve, c) voltage-charge curve, and d) flux-charge curve.

[0028] Some of the exemplary embodiments utilize the already existing functionalities of current oscilloscope such as for example but not limited to those commercially available from Tektronix®, Inc., USA, and advances them with a software wrapper in one implementation, to make improved oscilloscopes suitable for understanding nonlinear systems including memristors.

[0029] In another exemplary implementation, a hardware extension (digital or analog) is used for converting the existing oscilloscopes to the improved oscilloscopes to provide the outputs of the invention. [0030] FIG. 5 represents the graphical user interface flow and options 36 of one of the embodiment of the electrical measurement device of FIG. 1 for displaying two or more electrical signal representations.

[0031] In one of the embodiment of the invention, the channel representations or outputs from the improved oscilloscope using the electrical measurement device as described herein are provided as follows: a) 1 represents the channel signal from one of the input channel of the oscilloscope, b) 2 represent another signal from one of the input channel of the oscilloscope, c) 3 represents the integral of the signal representing 1, d) 4 represents the integral of the signal representing 2, g) In yet another embodiment of the invention, the signals 1,2,3,4 can interchange themselves.

[0032] In yet another embodiment of the invention, the mathematical function of integral can be interchanged by user defined or manufacturer defined mathematical function. These functions can be, but not limited to, exponents, nth differential of input/output current/voltage signals, a function involving one or more than one signals such as the division of voltage and current, current and current, voltage and voltage signals or their nth order derivatives; or using the variables of time, frequency and functions on them. These different functions can be implemented using analog or digital signals through ASICs, microcontrollers, DSP chips, analog arrays or FPGAs or any other analog or digital circuits. Further the functions described herein could be time variable or frequency variable, or both. [0033] In yet another embodiment of the invention, any or all of the signals 1,2,3,4 can be a line graph.

[0034] In yet another embodiment of the invention, any or all of the signals 1,2,3,4 and the curves can be stored and processed to display the trace slowly or incrementally.

[0035] In yet another embodiment of the invention, any or all of the signals 1,2,3,4, and the curves can be stored and processed at a later time.

[0036] In yet another embodiment of the invention, the number of signals can be increased with each pair being defined by a set of same or different mathematical functions being imposed on signals corresponding to channel 1 and signals corresponding to channel 2.

[0037] In yet another embodiment of the invention the improved oscilloscope can make subplots of one, some or all of the possible cases available in Chua's periodic table for memristor type non-linear devices, including memcap, memductor etc (L. Chua and S. Kang, "Memristive devices and systems," Proceedings of the IEEE, vol. 64, no. 2, pp.209-223, 1976, L.Chua, 'Nonlinear circuit foundations for nanodevices. I. The four-element torus' , Proceedings of the IEEE, 91,11, pp- 1830- 1859,2003). [0038] In yet another embodiment of the invention, the lissajous pattern can represent the plot of the signals representing channel 1 and channel 2 from previous frames or show the time elapsed along with the current frame.

[0039] In yet another embodiment of the invention, the lissajous pattern can represent the plot of the signal representing channel 1 and channel 2 from previous frames or the time elapsed along with the current frame in different colors representing the different frames or time snapshot of the input. These plots can form a video which shows the trace generated incrementally to indicate the change over time.

[0040] In one exemplary embodiment, a default mode for generating the two or more electrical representations could be set for generating simultaneous plots of charge-flux, charge-voltage, voltage-current, and flux-current plots. In this configuration, it would be appreciated by those skilled in the art that a charge or flux based memristor as a part of the DUT, can be studied and identified on the oscilloscope.

[0041] In another embodiment, the default mode could be set for simultaneous plot of current- time, voltage-time and resistance vs. max voltage plots. In this configuration, an I_max based memristor, as a part of the DUT can be studied. The default modes as referred herein may be made available through a user selectable menu through a user interface integrated with the output module.

[0042] In still yet another embodiment, the default mode may be configured to view the resistance vs. time plot, the output vs. input plot, the input signal vs. time plot to be able to identify the state variable.

[0043] In still yet another embodiment, the output module is configured for a default mode to switch through plots of voltage or current or first or higher order derivative of voltage or first or higher order derivative of currents or single or multiple integral of voltage or single or multiple integrals of current and voltage or current or first or higher order derivative of voltage or first or higher order derivative of currents or single or multiple integral of voltage or single or multiple integrals of current or a combination of these plots for identifying the DUT.

[0044] In one implementation, the user is provided an option through the user- interface to display specific time duration of the inputs and outputs. The input here would correspond to the stimulus signal applied to the DUT.

[0045] In another implementation, the user may select through a user-interface an option to view the plots being incrementally plotted with time. Thus in one implementation the user interface enables a user through a user input window to specify a sampling rate that is used as increment for stimulus signal/outputs or both for plotting. In one example this is done by choosing a start point as an initial value of input-output and selecting to obtain a trace or curve to reach a final value of input-output as a curve or vice versa. In other words, the user input includes an instruction to trace the inputs and outputs corresponding to the DUT either in a way that it starts from the initial value of input-output curve and reaches to final value of input-output curve or vice versa using the sampling rate. Thus, the user input in one example is a time duration that includes a start time and an end time for of either the stimulus signal or the one or more signals from the DUT or both. The start time and end time can be a forward time, for example time tl= 5 sec and time t2= 30 sec or it could be a vice versa that is a backward time, where tl= 30 sec and t2= 5 sec. The backward time tracing is specially useful for further analysis of the signals from DUT and analysis of characteristics of DUT. Thus, using the sampling rate one or more plots are generated that are independent plots or synchronized animated plots for a user-defined time interval or intervals. It would be appreciated by those skilled in the art that time evolution is critical to understand the behaviour of memristor device and hence a very advantageous representation.

[0046] In yet another implementation, the user may select to view the plots being incrementally plotted with time with simultaneous blurring or erasing previously plotted points.

[0047] In one embodiment of the invention the output module is a communication device. In yet another embodiment, the output module is a display device. In still yet another embodiment, the output module is coupled to a printing device. Referring back to FIG. 1, the electrical measurement device may also include a storage module 24 for storing and retrieving two or more electrical signal representations.

[0048] In yet another embodiment of invention the above mentioned outputs can be implemented as features through a software to upgrade current oscilloscopes, or through an application which can run on any computational device supported by a suitable operating system, or through an hardware upgrade that would use a microcontroller, microprocessor, and an analog circuit for capturing the two or more electrical signal representations and then transmitting these to a display unit via bluetooth, wires, internet, wireless etc.

[0049] Further, the processor module and the output module may be integrated in one exemplary embodiment or they may be a part of two distinct devices. In one specific non- limiting embodiment, the processor module incorporates a computational unit that can be a digitally controlled analog or digital unit that can create different functions through a set of basic functional operations, on the basis of which the two or more electrical representations get generated.

[0050] In another embodiment, the computational unit can be a mix of analog computational blocks combined with microprocessor/microcontroller based processing. In yet another embodiment, the computational unit and a memory unit that is a part of storage module or processor module, can be implemented on a computer, wherein the analog circuits are taken as inputs, digitized and fed to the computer. Or alternately, the computational unit and memory unit can be implemented on a computer with additional analog circuitry for function transformation. In still another alternate configuration, the computational unit can be a mix of analog computational blocks combined with microprocessor/microcontroller based processing.

[0051] Though the existing oscilloscopes can be upgraded as described above, the invention also includes fabricating a new oscilloscope incorporating the electrical measuring device as referred herein. In another embodiment, an additional unit may be added between the probe signals and the probe inputs of the oscilloscope, thus providing multiple displays.

[0052] In another embodiment, as would be appreciated by those skilled in the art, the memory unit may not be included, if a user only wants to plot the current data.

[0053] It would be appreciated by those skilled in the art that based on the settings chosen or selected by the user, the computational unit of the electrical measuring device would save the signal representations in the memory unit for a given period of history. Based on user inputs, the signal representations for particular time duration can be viewed, or the incrementally plotted data can be viewed by the user.

[0054] The inputs from the user may be received through a user interface and the outputs displayed on the user interface. Thus in one aspect the invention provides a user interface for displaying the two or more electrical signal representations. As mentioned herein above, the inputs from the user may include the number of simultaneous plots, the axis functions of the plots, how to display time data and an option to save data. The electrical measurement device can be configured to display default modes and default functions for user selection as described hereinabove. [0055] FIG. 6 is a flowchart representation 38 of a method for capturing and measuring electrical signals for a DUT according to one aspect of the invention. The method includes a step 40 for receiving one or more electrical signals from the DUT. At step 42, processing of the one or more electrical signals is done to calculate a plurality of characteristics for the one or more electrical signals. It would be appreciated by those skilled in the art that the processing of the one or more electrical signals is based on a user input in one non-limiting example, and in another example, the processing of the one or more electrical signals is based on a pre-defined selection. Based on the on the plurality of characteristics, at step 44 two or more electrical signal representations are generated. As described earlier, two or more different electrical signal representations are generated including but not limited to representations depicting the mathematical functions of one or more electrical signals. The method may also include a step 46 for storing and retrieving the two or more electrical signal representations.

[0056] It would be appreciated by those skilled in the art that the electrical measurement device and the method for capturing and measuring electrical signals for the DUT as described herein provide for an improved oscilloscope and user interface that utilizes the already available functionalities of oscilloscopes, develop new ones and advance them to meet with the challenges being posed by emerging circuit analysis. It would be further appreciated by skilled in the art that the electrical measurement device and the user interface as described herein provides new capabilities for displaying plots and graphs that are necessary and useful for measuring the characteristics of new circuit elements such as memristors, resistive RAMs and like that exhibit non-linear behavior and multiple stable states and devices incorporating such new circuit elements. The simultaneous and real time display of these plots and graphs as described herein is extremely advantageous in the research and industrial environment where testing of such circuit elements will be imperative for further developments and for quality control aspects. [0057] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

We Claim:

1. An electrical measurement device for capturing and measuring electrical signals, the electrical measurement device comprising: an input module coupled to a device under test (DUT), wherein the input module is configured to receive one or more electrical signals from the DUT; a processor module for processing the one or more electrical signals and to calculate a plurality of characteristics for the one or more electrical signals; and an output module configured to simultaneously display an output comprising two or more electrical signal representations based on the plurality of characteristics.

2. The electrical measurement device of claim 1 wherein the processor module is configured for processing the one or more electrical signals based on a pre-defined selection.

3. The electrical measurement device of claim 1 wherein the two or more electrical signal representations comprise mathematical functions of one or more electrical signals.

4. The electrical measurement device of claim 1 wherein the output comprises two or more of at least a voltage-current plot, a flux current plot, a voltage charge plot, and a flux charge plot for the one or more electrical signals.

5. The electrical measurement device of claim 1 wherein the output is generated upon an application of a stimulus signal on the DUT.

6. The electrical measurement device of claim 5 wherein the stimulus signal is a composite designed signal derived from a plurality of shaped signals in a form of rising and falling staircase of equal amplitude.

7. The electrical measurement device of claim 6 wherein the shaped signal comprises a triangular shaped signal.

8. The electrical measurement device of claim 5 wherein the processor module is configured for processing the one or more electrical signals based on a user input.

9. The electrical measurement device of claim 8 wherein the user input is a time duration.

10. The electrical measurement device of claim 9 wherein the time duration is a duration for the stimulus signal.

11. The electrical measurement device of claim 9 wherein the user input is a sampling rate for the two or more electrical signal representations.

12. The electrical measurement device of claim 11 wherein the time duration comprises at least one of a forward time or a backward time.

13. The electrical measurement device of claim 1 wherein the output is generated based on characteristics selected from current, voltage, time, frequency, flux, charge, maximum current for each polarity, maximum voltage for each polarity, bifurcation parameter, lyapunov exponent, eigen-vectors, user-postulated state variable governing memristance, conductance and resistance.

14. The electrical measurement device of claim 1 wherein the output module is configured for a default mode for generating the two or more electrical representations as simultaneous plots of current- time, voltage-time, resistance/conductance vs. max voltage plots in each direction, resistance/conductance vs. max current in each direction plots.

15. The electrical measurement device of claim 1 wherein the output module is configured for a default mode to switch through plots of voltage or current or first or higher order derivative of voltage or first or higher order derivative of currents or single or multiple integral of voltage or single or multiple integrals of current and voltage or current or first or higher order derivative of voltage or first or higher order derivative of currents or single or multiple integral of voltage or single or multiple integrals of current or a combination of these plots for identifying the DUT.

16. The electrical measurement device of claim 1 wherein the output module is configured for a default mode for generating the two or more electrical representations selected from resistance/conductance vs. time plot, current vs. voltage plot, current vs. time plot, voltage vs. time plot, resistance/conductance vs. user postulated state-variable plot to identify a state variable for the DUT.

17. The electrical measurement device of claim 1 further comprising a storage module for storing and retrieving the two or more electrical signal representations.

18. The electrical measurement device of claim 1 wherein the output module is a communication device.

19. The electrical measurement device of claim 1 wherein the output module is a display device.

20. A user interface configured to display simultaneously two or more electrical signal representations generated based on a plurality of characteristics of the one or more electrical signals received from a device under test (DUT).

21. The user interface of claim 20 further comprising display options for user selection for the two or more electrical signal representations.

22. The user interface of claim 21 further comprising a default mode for displaying the two or more electrical representations as simultaneous plots of charge-flux, charge-voltage, voltage-current, and flux-current plots.

23. The user interface of claim 21 further comprising a default mode for displaying the two or more electrical representations as simultaneous plots of current-time, voltage-time and resistance vs. max voltage plots.

24. The user interface of claim 21 further comprising a default mode for switching through plots of voltage or current or first or higher order derivative of voltage or first or higher order derivative of currents or single or multiple integral of voltage or single or multiple integrals of current and voltage or current or first or higher order derivative of voltage or first or higher order derivative of currents or single or multiple integral of voltage or single or multiple integrals of current or a combination of these plots for identifying the DUT.

25. The user interface of claim 21 further comprising default mode for generating the two or more electrical representations selected from resistance/conductance vs. time plot, current vs. voltage plot, current vs. time plot, voltage vs. time plot, resistance/conductance vs. user postulated state-variable plot identify a state variable for the DUT.

26. A method for capturing and measuring electrical signals for a device under test (DUT), the method comprising: receiving one or more electrical signals from the DUT; processing the one or more electrical signals to calculate a plurality of characteristics for the one or more electrical signals; and generating two or more electrical signal representations based on the plurality of characteristics.

27. The method of claim 26 wherein the processing of the one or more electrical signals is based on a user input.

28. The method of claim 26 wherein the processing of the one or more electrical signals is based on a pre-defined selection.

29. The method of claim 26 wherein the two or more electrical signal representations comprise mathematical functions of one or more electrical signals.

30. The method of claim 26 further comprising storing and retrieving the two or more electrical signal representations.