Patent ID: 12235307

Reference numerals utilized in the drawings include:1TLP system2device under test3pulse generator4input terminal5impedance path6sensor7transmission line8determination means10system11apparatus12conductor13sensing probe14measurement point15determination means16electrical autocorrelator17last measurement point18-20means21calibration means22integrated circuit device30system31determination means32attenuator40method41-44step

DETAILED DESCRIPTION

FIG.1is a schematic functional diagram of a known Transmission Line Pulse (TLP) system1for determining a response of a device under test2to an electrical pulse generated by a pulse generator3.

As shown inFIG.1, the pulse generator3respectively TLP pulser generates an electrical pulse that is transmitted to an input terminal4of the device under test2through a constant impedance path5. Therein, the electrical pulse generated by the pulse generator3is usually a substantially rectangular pulse, wherein the pulse can for example be generated in response to a signal of a personal computer connected to the pulse generator3. Further, the constant impedance path5can comprise a conventional cable or any other structure configured for coupling a pulse between two circuits or devices.

FIG.1further shows sensors6for sensing a current flowing in and a voltage applied to the constant impedance path5, wherein corresponding sensing probes, for example current probes and/or voltage probes, are inserted into the constant impedance path5to generate signals in response to the current flowing in respectively voltage applied to the constant impedance path5. There are further shown transmission lines7through which the signals generated by the sensing probes are transmitted to a determination means8that is configured for determining a response of the device under test2to the electrical pulse generated by the pulse generator3. However, that the signals generated by the sensing probes are transmitted to the determination means8via a transmission line should merely be understood as an example, and the signals generated by the sensing probes can also be transmitted to the determination unit in any other known form, for example wirelessly. As the sensing probes usually provide an analog output signal, these analog output signals may also first be inputted into a digitizer before being transmitted to the determination means8, wherein the digitizer provides a digital signal representation of the analog output signal.

Such a TLP system1is usually designed to measure the ways the device under test2, for example an integrated circuit, responds to current and voltage pulses that are delivered to it by the pulse generator3, wherein all elements apart from the device under test are adapted to the impedance of the constant impedance path5. Therein, the pulse generator3delivers an initial, or incident TLP pulse through the constant impedance path5to the input terminal4of the device under test2. When the incident TLP pulse reaches the device under test2, it is partly reflected by the device under test2and new current and voltage pulse waveforms result. The reflected pulse overlaps with the incident pulse as it travels back up the constant impedance path5in the opposite direction, toward the pulse generator3. The constant impedance path5is designed in a manner known in the art to avoid significant pulse distortions, so that the reflected pulse may be accurately measured by the sensing probes and the dynamic impedance of the device under test may be calculated in the determination means8by comparing the ratio of the incident and the reflected pulse.

Therein, typically current and/or voltage oscilloscope probes are used to measure the incident and the reflected current and/or voltage pulse waveforms. These probes are positioned in the constant impedance path5at a selected insertion point where the incident and the reflected pulses are expected to overlap. However, there is always a time delay between the incident and the reflected pulses when there is any length of cable between an oscilloscope probe and the device under test, wherein these delays usually cause measurement errors. Therefore, in known TLP techniques, the oscilloscope probes and the device under test are usually positioned close to each other, in order to avoid these measurements errors as much as possible. Therefore, although comparatively long pulses can be used, the time resolution that can be achieved is limited, wherein, however, in order to accurately determine the capacitive and inductive features of the device under test2, it is necessary to determine the voltage and the current at the device under test2with high time resolution.

Therefore, techniques with TLP pulse widths of less than 10 nanoseconds have been developed, which are commonly termed Very Fast TLP or VF-TLP. In Very Fast TLP systems usually a single voltage sensor is positioned between a pulse generator and a device under test in such a way, that the incident and reflected pulses can be separately recorded in terms of time, whereby the time resolution when determining the voltage and the current at the device can be significantly improved. However, for example due to cable loss, only a constant impedance cable of limited length, and therefore, only very short pulses can be used in Very Fast TLP systems.

Therefore, there is a need for a system for determining a response of a device under test to an electrical pulse generated by a pulse generator, wherein the pulse can have an arbitrarily long pulse duration, and wherein at the same time a high time resolution can be achieved.

FIG.2is a schematic functional diagram of a system10for determining a response of a device under test2to an electrical pulse generated by a pulse generator3, according to a first embodiment of the invention. Therein, the same elements as inFIG.1are given the same reference numbers as inFIG.1and are not discussed in any further detail here.

As shown inFIG.2, the system10comprises the device under test2, the pulse generator3, and an apparatus11for determining a response of the device under test2to an electrical pulse generated by the pulse generator3, wherein the apparatus11comprises a conductor12for coupling the electrical pulse generator to the device under test2, wherein the conductor12has a predetermined electrical impedance and a predetermined pulse propagation velocity. Further, at least two sensing probes13are connected to the conductor12, wherein two sensing probes are shown inFIG.2, and wherein each of the at least two sensing probes13is positioned at one of at least two measurement points14on the conductor12and is configured to generate a signal in direct proportion to a current flowing in or voltage applied to the conductor12at the corresponding measurement point14, and a determination means15for determining the response of the device under test2to the electrical pulse based on the signals generated by the at least two sensing probes13. Therein, the two sensing probes13shown inFIG.2are positioned at different measurement points14of the at least two measurement points, wherein a distance d between these different measurement points on the conductor is defined in such a way, that a transit time of the electrical pulse between these different measurement points14can be determined, wherein the determination means15is configured to determine the response of the device under test2based on the signals generated by the at least two sensing probes13and the transit time of the electrical pulse between these different measurement points14.

Therein, that the conductor12has a predetermined electrical impedance means that the electrical characteristic wave impedance of the conductor12is known, wherein preferably the electrical impedance of the conductor12is constant over the entire length of the conductor12. Further, that the conductor12has a predetermined pulse propagation velocity means that the pulse propagation velocity of the conductor12is known, wherein preferably the pulse propagation velocity is constant over the entire length of the conductor12. Furthermore, the conductor12can again comprise a conventional cable or any other structure configured for coupling a pulse between two circuits or devices, wherein all elements apart from the device under test2can again be adapted to the predetermined electrical impedance.

FIG.2shows a system10with an improved apparatus11for determining a response of the device under test2to an electrical pulse generated by the pulse generator3, wherein the pulse can have an arbitrarily long pulse duration, and wherein at the same time a high time resolution can be achieved. In particular, as at least two of the at least two sensing probes13are positioned at different measurement points14of the at least two measurement points14, the incident and reflected pulses do not have to be recorded well-separated in terms of time, wherefore compared to known Very Fast TLP systems a shorter conductor12can be used and the electrical pulse can have a comparatively long pulse duration. Further, due to the fact that distances d between these different measurement points14on the conductor12are defined in such a way, that transit times of the electrical pulse between these different measurement points14can respectively be determined, for example by the determination means, signal transients are different at the at least two measurement points, wherefore they can be used to determine the response of the device under test2, wherefore, compared to known TLP systems1, the voltage and the current at the device under test2can be determined with high time resolution. Therefore, a system10with an apparatus11that combines the advantages of both, a common TLP-system and a common Very Fast TLP system, is provided.

According to the embodiments ofFIG.2, the transit time of the electrical pulse between the different measurement points is determined by an electrical autocorrelator16. However, that the transit time is determined by an electrical autocorrelator should merely be understood as an example, and the transit time can also be determined by any other known means configured to determine a transit time of an electrical pulse. Further, for example the transit time, can also be determined by the sensing probes and determination means, and/or time stamps may be added to the signals generated by the corresponding sensing probes, wherein the transit time is determined based on the time stamps. On the other hand, the test arrangement, and therefore, also the transit time between these different measurement points may already be known, wherein the corresponding transit time can for example be stored in a look-up table, and wherein the transit time can be determined based on the look-up table.

The determination means can further for example be an oscilloscope. However, at least parts of the determination means can also be realized by code that is stored in a memory and executable by a processor.

According to the embodiments ofFIG.2, each of the at least two sensing probes13is further configured to generate a signal in direct proportion to the voltage applied to the conductor12.

Further, as can be seen inFIG.2, each of the at least two sensing probes13is positioned at a separate measurement point14, wherein a distance d between two successive measurement points is defined in such a way, that a transit time of the electrical pulse between the corresponding successive measurement points14,17can be determined, and wherein a distance between a last measurement point17and the device under test2is defined in such a way, that a transit time of the electrical pulse between the last measurement point17and the device under test2can be determined, and wherein the determination means15is configured to determine the response of the device under test2based on the signals generated by the at least two sensing probes, the respective transit times of the electrical pulse between successive measurement points14,17, and possibly also the transit time of the electrical pulse between the last measurement point17and the device under test2.

Therein, the last measurement point17is the measurement point closest to the device under test2.

The determination means15is configured to determine a change of a voltage generated at the device under test2in response to the electrical pulse over time and/or a change of a current generated at the device under test in response to the electrical pulse over time. Therein, the determination means15may for example be configured to provide a video display of the change of the voltage generated at the device under test2in response to the electrical pulse over time and/or the change of the current generated at the device under test2in response to the electrical pulse over time.

In particular, as can be seen inFIG.2, the shown apparatus11comprises two sensing probes13, wherein each of the two sensing probes13is configured to generate a signal in direct proportion to the voltage applied to the conductor12, wherein a distance d between the corresponding two measurement points14,17is defined in such a way, that a transit time of the electrical pulse between the measurement points can be determined. As can be also seen inFIG.2, the shown determination means15comprises a means18for iteratively determining a voltage profile of the electrical pulse and a voltage profile of a part of the electrical pulse that is reflected at the device under test based on the signals generated by the two sensing probes13, and a transit time of the pulse between the corresponding measurement points14,17, and a means19for determining the change of the voltage generated at the device undertest2in response to the electrical pulse over time and the change of the current generated at the device under test2in response to the electrical pulse over time based on the voltage profile of the electrical pulse, the voltage profile of the part of the electrical pulse that is reflected at the device under test, and the predetermined electrical properties of the conductor, for example an electrical wave impedance or attenuation.

The shown determination means15further comprises a means zo for preprocessing the signals generated by the sensing probes13, wherein the means zo for preprocessing the signals generated by the sensing probes13can for example include a digitizer that provides a digital signal representation of analog output signals generated by the sensing probes13, a means for performing mathematical operations, for example filter operations on the analog output signals and/or the digital representation of the analog output signals, and/or a selecting means for selecting sensing probes of which the generated signals should be further processed.

It should be appreciated that the determination means15can include, for example, a determination device that includes hardware. The determination device can include, for example, hardware that is configured to determine a response of the device under test2based on a pre-defined process and one or more parameters. The parameters, can include, for example, parameters discussed herein (e.g. signals generated by the sensing probes13and the transit time of the electrical pulse between these different measurement points of the sensing probes13, etc.).

As shown inFIG.2, the apparatus11further comprises a calibration means21configured to calibrate the parameters of the setup before the response of the device under test2is determined. The calibration means21is configured to synchronize the sensing probes13, to take into account their exact sensitivities or to take into account the parameters that are required by the means18in order to perform the corresponding determinations. Therein, the calibration can at least in part be done by utilizing dedicated calibration experiments.

According to the embodiments ofFIG.2, the apparatus11is additionally configured to perform Very Fast TLP testing of the device under test2. In particular, if the pulse is short enough and it is selected in the means20for processing the signals generated by the sensing probes13that only the signals generated by the sensing probe13positioned at the last measurement point17should be processed, the procedure is equal to Very Fast TLP testing.

The device under test can be an integrated circuit device22. In particular, it is useful to measure the ways integrated circuits respond to electrical pulses when evaluating their electrostatic discharge (“ESD”) protection. Further, with faster technologies like SiC and GaN, the transit behavior of switching power devices, modules, and systems becomes increasingly important and has to be analyzed.

FIG.3is a schematic functional diagram of a system30for determining a response of a device under test2to an electrical pulse generated by a pulse generator3, according to a second embodiment of the invention. Therein, the same elements as inFIG.1orFIG.2are given the same reference numbers as inFIG.1and are not discussed in any further detail here.

As shown inFIG.3, also the system30according to the second embodiment comprises the device under test2, the pulse generator3, and the apparatus11for determining a response of the device under test2to an electrical pulse generated by the pulse generator3, wherein the apparatus11comprises a conductor12for coupling the electrical pulse generator to the device under test2, wherein the conductor12has a predetermined electrical impedance and a predetermined pulse propagation velocity. Further, at least two sensing probes13are connected to the conductor12, wherein two sensing probes are shown inFIG.3, and wherein each of the at least two sensing probes13is positioned at one of at least two measurement points14on the conductor12and is configured to generate a signal in direct proportion to a current flowing in or voltage applied to the conductor12at the corresponding measurement point14, and a determination means31for determining the response of the device under test2to the electrical pulse based on the signals generated by the at least two sensing probes13, wherein at least two of the at least two sensing probes13are positioned at different measurement points14of the at least two measurement points, wherein a distance d between two of these different measurement points on the conductor is respectively defined in such a way, that a transit time of the electrical pulse between these two different measurement points14can be determined, wherein the determination means31is configured to determine the response of the device under test2based on the signals generated by the at least two sensing probes13and the transit times of the electrical pulse between these different measurement points14.

The main difference between the system30according to the second embodiment as shown inFIG.3and the system10according to the first embodiment as shown inFIG.2is that the determination means31of the system30according to the second embodiment is that in the system according to the second embodiment attenuators32are positioned between one or more pairs of sensing probes, wherein the system30is configured to determine the response of the device under test based on the signals generated by the at least two sensing probes, the transit time of the electrical pulse between these different measurement points and additional effects like noise, disturbances, reflection and attenuation along the conductor12.

Interferences, which usually occur in non-ideal systems and which can for example include noise, disturbances, reflections or signal attenuations, can for example result in the fact that signals reconstructed by the determination means31show an increasing noise amplitude and/or a distorted signal slope, especially if the determination means31is configured to reconstruct these signals based on an iterative process. Therein, the signal slope can be an artefact, that results from reflections and/or signal attenuations within the conductor, respectively when the electrical pulse travels through the conductor. However, if reflections and damping along the conductor are correctly taken into account by the determination means31, the signal slope can be determined correctly. Further, if filtering steps are included in the process to reconstruct the signals, artificial increasing of the noise amplitude can be avoided. Further, an increase of the artificial noise can be reduced by integrating the attenuators32into the setup, provided that the determination means31takes damping into account.

Thereby, the determination of the response of the device can be further improved, as such interferences occur in usual non-ideal systems.

According to the embodiment ofFIG.3, the shown apparatus11further comprises attenuators32, wherein respectively one attenuator32is positioned between two of the sensing probes13. By integration of these attenuators, the corresponding attenuation factors can be decreased.

FIG.4is a flow chart of a method40for determining a response of a device under test to an electrical pulse generated by a pulse generator, according to embodiments of the invention.

Therein, according to the embodiments ofFIG.4, the method40comprises the steps of generating an electrical pulse by a pulse generator41, and coupling the electrical pulse to the device under test by a conductor42, wherein the conductor has a predetermined electrical impedance and a predetermined pulse propagation velocity.

The shown method40further comprises the step of respectively generating a signal that is in direct proportion to a current flowing in or a voltage applied to the conductor by at least two sensing probes connected to the conductor43, wherein each of the at least two sensing probes is positioned at one of at least two measurement points on the conductor and is configured to generate an electrical signal in direct proportion to the current flowing in or the voltage applied to the conductor at the corresponding measurement point. Therein, at least two of the at least two sensing probes are positioned at different measurement points of the at least two measurement points, wherein a distance d between two of these different measurement points on the conductor is respectively defined in such a way, that a transit time of the electrical pulse between these two different measurement points can be determined.

There is further shown a step determining the response of the device under test to the electrical pulse based on the signals generated by the sensing probes44, wherein the response of the device under test is further determined based on the signals generated by the at least two sensing probes and the transit times of the electrical pulse between these different measurement points.

According to the embodiments ofFIG.4, the step of determining the response of the device under test based on the signals generated by the at least two sensing probes44further comprises determining the response of the device under test based on the signals generated by the at least two sensing probes, the transit times of the electrical pulse between these different measurement points and interferences, for example reflection and attenuation along the signal path.

In particular, auxiliary functions that take into account the interferences can be used to determine the response of the device under test, wherein, considering a situation that two sensing probes are connected to the conductor, the auxiliary functions Uhhregarding the travelling of the electrical pulse from the pulse generator to the device under test and Urrregarding the travelling of the part of the electrical pulse in the direction back to the pulse generator can be defined as follows:

Uh⁢h(t):=δ1⁢2·s1(t-T1⁢2)+r21+r2·s2(t)-δ1⁢22(1+2⁢r2)1+r2·s2(t-2·T1⁢2)(1⁢a)
respectively in the Laplace representation

Uh⁢h:=δ1⁢2⁢e-s⁢T1⁢2⁢s1+(r21+r2-δ1⁢22(1+2⁢r2)1+r2⁢e-s⁢2⁢T1⁢2)⁢s2(1⁢b)with⁢Uh⁢h(t)=UH⁢2(t)-δ1⁢22⁢UH⁢2(t-2·T1⁢2)(2⁢a)
respectively in the Laplace representation

Uh⁢h=(1-δ1⁢22⁢e-s⁢2⁢T1⁢2)⁢UH⁢2(2⁢b)and⁢Ur⁢r(t):=-δ1⁢2·s1(t-T1⁢2)+11+r2·s2(t)+δ1⁢22⁢2⁢r21+r2·s2(t-2·T1⁢2)(3⁢a)
respectively in the Laplace representation

Ur⁢r:=-δ1⁢2⁢e-s⁢T1⁢2⁢s1+(11+r2+δ1⁢22⁢r21+r2⁢e-s⁢2⁢T1⁢2)⁢s2(3⁢b)with⁢Ur⁢r(t)=UR⁢2(t)-δ1⁢22⁢UR⁢2(t-2·T1⁢2)(4⁢a)
respectively in the Laplace representation
Urr=(1−δ122e−s2T12)UR2(4b),
wherein δ12is the attenuation factor of the attenuation of a signal travelling within the conductor from the first sensing probe to the second sensing probe, wherein the signal is in direct proportion to the voltage applied to a conductor, esT12and es2T12are operators that respectively define a propagation delay T12regarding the signal travelling from the first sensing probe to the second sensing probe, s1is the strength of the signal acquired respectively generated at the first sensing probe at a particular time, r2is the reflection factor regarding reflections of the signal at the second sensing probe, UH2represents the signal travelling from the pulse generator to the device under test after having travelled through the second sensing probe, s2is the strength of the signal acquired respectively generated by the second sensing probe at the particular time, and UR2represents the part of the signal that has been reflected by the device under test and is travelling back in the direction to the pulse generator after having travelled up to the second sensing probe. Therein, the factors δ12and r2can for example be derived based on the calibrations of the two sensing probes.

Based on these auxiliary functions, UH2and UR2can then be derived as follows, using an iterative process:
UH2(t)=Uhh(t)+δ122Uhh(t−2·T12)+δ122Uhh(t−4·ΔT12)+δ122Uhh(t−6·T12)+  (5a)
respectively in Laplace representation
UH2=Uhh+δ122e−s2T12Uhh+δ124e−s4T12Uhh+δ126e−s6T12Uhh+  (5b)
and
UR2(t)=Urr(t)+δ122Urr(t−2·T12)+δ124Urr(t−4·T12)+δ126Urr(t−6·T12)+  (6a)
respectively in Laplace representation
UR2=Urr+δ122e−s2T12Urr+δ124e−s4T12Urr+δ126e−s6T12Urr+  (6b)

Thereafter, the electrical pulse travelling through the conductor from the pulse generator to the device under test Uhand the part of the electrical pulse that is reflected at the device under test and travelling back through the conductor Urcan be reconstructed based on the following equations:

Uh(t)=δ2⁢P⁢UH⁢2(t-T2⁢P)(7⁢a)respectively⁢Uh=δ2⁢P⁢e-s⁢T2⁢P⁢UH⁢2(7⁢b)and⁢Ur(t)=1δ2⁢P⁢UR⁢2(t+T2⁢P)(8⁢a)respectively⁢U=1δ2⁢P⁢e-s⁢T2⁢P⁢UR⁢2,(8⁢b)
wherein δ2Pis the attenuation factor of the attenuation and T2Pis the transit time of a signal, respectively travelling within the conductor from the second sensing probe to the device under test.

Further, a change of a voltage generated at the device under test in response to the electrical pulse over time, UDUT(t). And a change of a current flowing into the device under test in response to the electrical pulse over time. IDUT(t), can then be determined based on these reconstructed voltage profiles Uh(t) and Ur(t) and the wave impedance Z0of the conductor using the following well-known equations:
UDUT(t)=Uh(t)+Ur(t)  (9a)
Z0·IDUT(t)=Uh(t)−Ur(t)  (9b)

Therein, the influence of noise can be further reduced by combining the above-stated derivation of Uhand Urwith filtering operations, for example utilizing an additional filtering operation in each iteration step. Further, remaining distortions due to dispersions can be compensated by slightly amending the above-stated auxiliary functions or by using known unfolding processes.

Further, by respectively positioning one attenuator32positioned behind one of the sensing probes with respect to a direction from the pulse generator to the device under test, the attenuation factor δ12decreases, whereby the above-stated derivation of Ph and Pr can be further simplified, as the ascending powers of δ12converge towards zero

FIG.5A-5Gillustrate the determination of a voltage profile of the electrical pulse and a voltage profile of a part of the electrical pulse that is reflected at the device under test, according to one embodiment of the invention.

In particular,FIG.5A-5Gillustrate the determination of a voltage profile of the electrical pulse and a voltage profile of a part of the electrical pulse that is reflected at the device under test according to one embodiment of the invention, in which a signal that is in direct proportion to the voltage applied to the conductor is respectively generated by two sensing probes, wherein a distance between the corresponding two measurement points is defined in such a way, that a transit time of the electrical pulse between the two measurement points can be determined.

Therein,FIG.5Ais a diagram illustrating the time course of a voltage US, sensed with a first sensing probe, respectively at a first measurement point, and the time course of a voltage US2sensed with a second sensing probe, respectively at a subsequent second measurement point, wherein the second measurement point is closer to the device under test than the first measurement point. Here, the vertical axis represents the sensed voltage and the horizontal axis represents the time t. As can be seen inFIG.5A, the voltage curves are almost equal apart from that the time course of the voltage US, sensed at the first measurement point and the time course of the voltage US2sensed at the second measurement point are time shifted, wherein this time shift is based on the transit time T12of the electrical pulse between the first measurement point and the second measurement point, and wherein the electrical pulse first reaches the first sensing probe, whereas the part of the electrical pulse that is reflected at the device under test first reaches the second sensing probe. Therefore, the first and second measurement points are to be separated by a distance equal to the velocity of light in the conductor multiplied by T12such that T12as the transit time of the electrical pulse between these different measurement points can be determined.

The voltage curves shown inFIG.5Arespectively result from the electrical pulse, respectively the incident pulse Lin being overlaid by the part of the electrical pulse that is reflected at the device under test, respectively the reflected pulse Ur. The incident pulse Uhis shown in the diagram shown inFIG.5Band the reflected pulse Uris shown in the diagram shown inFIG.5C. Further, the incident pulse Uhoverlaid by the reflected pulse Uris illustrated in the diagram shown inFIG.5Dthat illustrates the voltage at the device under test. Here, the vertical axis respectively represents the sensed voltage and the horizontal axis respectively represents the time t.

FIGS.5E and5Fnow describe how a voltage profile of the electrical pulse and a voltage profile of a part of the electrical pulse that is reflected at the device under test are determined. Therein,FIG.5Eis a diagram illustrating the time course of the voltage US, sensed at the first measurement point andFIG.5Fis a diagram illustrating the time course of the voltage US2sensed at the subsequent second or last measurement point. Here, the vertical axis respectively represents the sensed voltage and the horizontal axis respectively represents the time t.

As can be again seen inFIGS.5E and5F, the time course of the voltage US, sensed at a first measurement point and the time course of the voltage US2sensed at the subsequent second or last measurement point are almost equal apart from that the time course of the incoming pulse Uhand the reflected pulse Urare time shifted in a different way, wherein the difference between these time shifts is based on the transit time of the electrical pulse between the first measurement point and the second measurement point. The second measurement point is located closer to the device under test than the first measurement point. However, as, according to the invention, this transit time between the first measurement point and the second measurement point respectively the second measurement point and the first measurement point is determined and taken into consideration, and as the voltage curves shown inFIGS.5E and5Frespectively consist of the voltage profile of the incoming electrical pulse and the voltage profile of the part of the electrical pulse that is reflected at the device under test at the corresponding measurement point, the voltage profile of the electrical pulse and the voltage profile of the part of the electrical pulse that is reflected at the device under test can be determined based on the signals generated by the two sensing probes, and a transit time of the pulse between the two measurement points.

For example, the incoming voltage profile of the electrical pulse Uhand the voltage profile of the part of the electrical pulse that is reflected at the device under test Urcan respectively be determined in time segments as shown inFIG.5EandFIG.5F. Therein, a first segment Uh0of the signal US2shown inFIG.5Fonly consists of the incoming pulse Uhand is identical to the respective first segment of the signal US1that is also indicated as Uh0inFIG.5E. The next segment Uh1of signal US1shown inFIG.5E, starting at time t1, still only consists of the incident pulse Uh. The respective segment of the signal US2, which is following Uh0and starts at t1′ as shown inFIG.5F, results from the sum of the segment Uh1of the incoming pulse and the first segment Ur1of the reflected pulse Ur. Thus, the first segment Ur1of the reflected pulse in the time segment starting at time t1′ can be computed by subtracting Uh1from US2, as shown inFIG.5F.

After Ur1has been determined in this way, the next sector Uh1of the incoming pulse in the time segment starting with t2can be calculated by subtracting Ur1from US1, as shown inFIG.5F.

Similarly, for subsequent sectors, Urncan be calculated by subtracting, Uhnfrom US2and subsequent sectors Uh(n+1)can be calculated by subtracting Urnfrom US1, as indicated inFIG.5EandFIG.5F, wherein the index n defines the number of the corresponding segment.

Based on the values thus obtained, the voltage profile of the electrical pulse and the voltage profile of the part of the electrical pulse that is reflected at the device under test can then be reconstructed. Further, a change of a voltage generated at the device under test in response to the electrical pulse over time and a change of a current flowing to the device under test in response to the electrical pulse over time can then be determined based on these reconstructed voltage profiles and the predetermined properties of the conductor, and based on known physical dependencies between these parameters, for example by using equations (9a) and (9b). For example,FIG.5Gis a diagram that illustrates the physical dependence between the current generated at the device under test and the reconstructed voltage profile as well as the predetermined impedance.

A technical feature or several technical features which has/have been disclosed with respect to a singular or several embodiments disclosed herein before, e.g. where a sensing probe positioned at one of at least two measurement points on the conductor is configured to generate a signal in direct proportion to a current flowing in the conductor, may be present also in another embodiment, e.g. where a sensing probe positioned at another one of at least two measurement points on the conductor is configured to generate a signal in direct proportion to a voltage applied to the conductor, except it is/they are specified not to be present or it is impossible for it/them to be present for technical reasons. Thus, while certain exemplary embodiments of the method, process, apparatus, system and methods of making and using the same have been shown and described above, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.