SEARCH FUNCTION WITH DEVICE MODELING

Abstract

In some implementations, a method may include acquiring a first plurality of measurements for the DUT, wherein the test and measurement instrument is not configured with the characteristic of the DUT and may include the first plurality of measurements for the characteristic. Additionally, the method may include determining an exponential model of the DUT based on the first plurality of measurements, wherein the exponential model is representative of the behavior of the DUT. The method may include acquiring a second plurality of measurements different from the first plurality of measurements, wherein the second plurality of measurements may include measurements for the characteristic of the DUT. Furthermore, the method may include verifying the exponential model based on the second plurality of measurements.Furthermore, the method may include adapting the behavior of the test and measurement instrument based on the verified exponential model of the DUT.

Description

CROSS-REFERENCE TO A RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 620,350, entitled "SEARCH FUNCTION WITH DEVICE MODELING," filed January 12, 2024, the disclosure of which is incorporated herein by reference in its entirety. FIELD OF TECHNOLOGY

[0002] Examples of the present disclosure relate generally to test and measurement instruments, and more particularly to a search function for a test and measurement instrument. BACKGROUND

[0003] In device testing, search functions are used to find specific device parameters. An example of a search function is determining the threshold voltage for a metal-oxide-semiconductor field-effect transistor (MOSFET), which is the voltage that must be present between the gate and source of the MOSFET for the MOSFET to be "turned on" and conduct (defined by a specific current level). The search function is given a target current and a voltage range in which to search for the threshold voltage at which the MOSFET conducts the target current. Any approach to determining the parameter must iteratively generate voltages to bring the conducted current closer to the target current, obtain a final current reading close enough to the target current, and be able to complete the search in a timely manner.

[0004] One solution is to use a binary search algorithm. The binary search algorithm iteratively performs measurements at the midpoints between a lower limit and an upper limit of a previous measurement. When using a binary search algorithm, the first measurement is the midpoint between the lower and upper limits. If the current is lower than the target current, the threshold voltage must be higher than the midpoint. The midpoint then becomes the lower limit, halving the range of possible results. The next measurement is again taken at the midpoint, again halving the space of possible results. Since each iteration halves the resolution, the number of possible results for a binary search is 2. N , where N is the number of iterations and the resolution is the inverse: 1 / 2 N .

[0005] While the binary search algorithm is particularly robust, the advantages of the binary search algorithm lie in its simplicity and easy computation, which allows for higher sampling frequencies. However, for the measurements required in these noise reduction applications, the measurement time for the binary search algorithm is relatively long (on the order of milliseconds), so the computation time is negligible. Furthermore, accuracy is the goal, but adding another measurement to further narrow the resolution would add more search time. The binary search algorithm also makes assumptions that may go unnoticed in some applications but become apparent in others. The binary search algorithm assumes that a referenced voltage value is the exact measured value on the device under test (DUT), which is not the case.The binary search algorithm has no method to account for this error. Furthermore, if the binary search algorithm mistakenly decides that the resulting voltage is less than or greater than a particular voltage it thought it was testing, the binary search algorithm will never be able to settle on the correct side of the particular voltage it intended to test: errors are irrecoverable.

[0006] The binary search algorithm is functionally a one-dimensional algorithm that shifts the voltage left or right along the x-axis depending on whether the measurement result is above or below the target value. The precision current measurement on a continuous value domain is converted into a binary value that can be acted upon: above or below the target value. In one working example of a binary search, the process was represented on a single x-axis for the control variable, the voltage. This example of a binary search works well when no assumptions can be made about the functional relationship between the input and output variables, other than that it is an injective (one-to-one) function. SUMMARY

[0007] A system comprising one or more computers can be configured to perform specific operations or actions by installing software, firmware, hardware, or a combination thereof on the system that, when operated, causes the system to perform the actions. One or more computer programs can be configured to perform specific operations or actions by including instructions that, when executed by a data processing device, cause the device to perform the actions.

[0008] In a general aspect, a method may include acquiring a first plurality of measurements for the DUT, wherein the test and measurement instrument is not configured with the characteristic of the DUT and may include the first plurality of measurements for the characteristic. The method may also include determining an exponential model of the DUT based on the first plurality of measurements, wherein the exponential model is representative of the behavior of the DUT. The method may further include acquiring a second plurality of measurements different from the first plurality of measurements, wherein the second plurality of measurements may include measurements for the characteristic of the DUT. The method may further include verifying the exponential model based on the second plurality of measurements.The method may further comprise adapting the behavior of the test and measurement instrument based on the verified exponential model of the DUT. Other embodiments of this aspect include corresponding computer systems, apparatus, and programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0009] In one general aspect, a test and measurement system may include a test and measurement instrument having one or more connectors for connecting the test and measurement instrument to a device under test (DUT). The test and measurement system may include memory.The test and measurement system may include one or more processors configured to execute code stored in memory, the code causing the one or more processors to: acquire a first plurality of measurements for a parameter of the DUT, wherein the test and measurement instrument is not configured with the parameter of the DUT; determine an exponential model of the parameter of the DUT based on the first plurality of measurements; acquire a second plurality of measurements for the parameter of the DUT, wherein the second plurality of measurements is different from the first plurality of measurements; verify the exponential model based on the second plurality of measurements; and adjust the behavior of the test and measurement instrument based on the verified exponential model of the DUT.Other embodiments of this aspect include corresponding computer systems, devices, and programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0010] In one general aspect, a test and measurement system may include a test and measurement instrument having one or more ports for connecting the test and measurement instrument to a device under test (DUT). The test and measurement system may include memory. The test and measurement system may include one or more processors configured to execute code stored in the memory, wherein the code causes the one or more processors to determine a model of a parameter of the DUT based on three measurements of the parameter by the test and measurement instrument, verify the model based on a fourth measurement and a fifth measurement of the parameter by the test and measurement instrument, and adjust the behavior of the test and measurement instrument for the parameter based on the verified model of the DUT.Other embodiments of this aspect include corresponding computer systems, devices, and programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0011] These and other aspects can be understood from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order that the manner in which the above-mentioned features may be understood in detail, a more detailed description, briefly summarized above, may be given by reference to exemplary embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings show only typical embodiments and are therefore not to be considered as limiting the scope of protection. Fig. 1 shows a test and measurement system 100 with a test and measurement instrument according to some examples. The Fig. 2-6 show the parameters for measurements to characterize a device using the search function described here according to some examples. Fig. 7 is a flowchart of a process of the search function according to some examples.

[0013] To facilitate understanding, identical reference numbers have been used, where possible, to designate identical elements common to the figures. It is contemplated that elements of one example may be advantageously incorporated into other examples. DETAILED DESCRIPTION

[0014] Various features are described below with reference to the figures. It should be noted that the figures may or may not be drawn to scale, and that elements of similar structure or function are represented by like reference numerals throughout the figures. It should be understood that the figures are provided only to facilitate description of the features. They are not intended to be exhaustive of the specification or to limit the scope of the claims. Furthermore, an illustrated example may not have all of the aspects or advantages shown. An aspect or advantage described in connection with a particular example is not necessarily limited to that example and may be realized in other examples, even if not shown or expressly described.

[0015] Fig. 1 shows a test and measurement system 100 including a test and measurement instrument, referred to as test and measurement instrument 102, connected via a network 104 to a user device having a user interface 110 according to embodiments of the disclosure. Measurement data generated by test and measurement instrument 102 is transmitted via network 104 and is accessible to user device 108. Accessing the measurement data includes streaming, displaying, and analyzing the data using user interfaces 110 of user device 108 to establish and modify training measurements, including various data transformations of the measurement data of test and measurement instrument 102. In some examples, the user may use user device 108 to change training parameters and / or settings for the search function described herein.In further examples, the user may use the user device 108 to visualize a model of the device characteristics and / or parameters, as further described herein.

[0016] In the test and measurement system 100 of Fig. 1, the test and measurement instrument 102 includes one or more processors 114, a memory 116, a display 118, and a user interface 120, which may be part of a touchscreen display or may take the form of control buttons and other user input devices. The one or more main processors 114 are configured to execute instructions from the memory 116 to implement any methods and associated steps defined by such instructions to control the overall operation of the test and measurement instrument 102. One or more measurement units 122 within the test and measurement instrument 102 perform the primary functions of measuring parameters and other qualities of signals from a device under test (DUT) 124 being tested or analyzed by the test and measurement system 100.Some measurements performed by the one or more measurement units 122 include measuring voltage, current, and power of input signals in the time domain, as well as measuring characteristics of the signals in the frequency domain. The one or more measurement units 122 represent any components for performing measurements typically performed in test and measurement instruments. The test and measurement instrument 122 is coupled to the DUT 124 via a connection 126, e.g., via one or more cables or other suitable types of electrical connections.

[0017] In some examples, memory 116 includes instructions for implementing search function 128 and the model derived from search function 128. Accordingly, the one or more main processors 114 of test and measurement instrument 102 are configured to execute instructions from memory 116 to implement search function 128. Further details about search function 128 and the corresponding model are described herein.

[0018] The test of the DUT 124 by the test and measurement instrument 102 generates measurement values that can be transmitted over the network 104 to the user device 108. For these transmissions, a network port 138 of the test and measurement instrument 102 is connected to the network 104 via a connection 130 and further to the user device 108 via a network connection 132. In this way, the network port 138 enables the test and measurement instrument 102 to transmit measurements acquired over the network 104 to the user device 108. In some examples, the test and measurement instrument 102 is directly coupled to the user device 108, and thus the test and measurement instrument 102 transmits the acquired measurements directly to the user device 108.

[0019] Once the measurements acquired by the test and measurement instrument 102 have been transferred or uploaded to the user device 108, users can access the acquired measurements, as well as any other information associated with the acquired measurements, via the configuration of the user device 108 in order to work with the acquired measurements and analyze them from various perspectives. The user device 108 is connected to the test and measurement instrument 102 via the port 134 through the network connection 132 and the network 104. The user interface 110 of the user device 108 can be configured to access, display, and communicate the acquired measurements.

[0020] As already mentioned, the user device 108 is the only one of the Fig. 1, however, system 100 may include any number of user devices having similar components and corresponding user interfaces 110. User device 108 includes one or more processors 140, memory 142, display 144, and user interface 110. The one or more processors 140 are configured to execute instructions from memory 142 to implement methods defined by such instructions and thereby control the overall operation of user device 108. Display 144 may be any suitable type of digital screen, such as an LED display or an LCD display, or any other suitable type of display. Display 144 renders or displays windows generated by user interface 110 for viewing by a user of user device 108.The user interface 110 may include a keyboard, a mouse, a touchscreen, or other suitable controls that a user may use to interact with the user device 108.

[0021] In test and measurement system 100, network 104 may be a closed network, i.e., a network available only to users of a particular company, building, or private network, or an open network, e.g., including the Internet, a virtual private network, and other suitable types of network architectures. Network connections 130 and 132 between the components of test and measurement system 100 may be any suitable type of wired or wireless network, including near-field communication (NFC) connections, infrared (IR) connections, Bluetooth® connections, Wi-Fi connections, Ethernet connections, etc.

[0022] This disclosure describes a search function (e.g., the search function 128 in Fig. 1) For device characterization. Device characterization is performed to find parameters used in the circuit design process to model behavior. In the manufacturing process, devices (e.g., DUTs) are tested to ensure compliance with published specifications. At the beginning of testing, the exact behavior of the DUT is unknown. However, the general pattern for the DUT's behavior is inherent. In metal-oxide-semiconductor field-effect transistors (MOSFETs), for example, at low gate-source voltages (Vgs), the drain-source current (Ids) increases exponentially as Vgs is increased. The current only increases significantly when Vgs exceeds the threshold voltage (Vth): a critical parameter. The value of Vth varies due to processing irregularities and impurities.

[0023] If the general relationship between Vgs and Ids is known to be exponential, preliminary measurements can be used as data points to define an exponential curve for a model of the device. The model is then used to determine the approximate value for Vth, which is measured and then used to further refine the model. While the present disclosure relates to exponential functions, it is not limited to exponential functions and may also be applied to other mathematical functions, such as polynomial functions, that represent characteristics of the DUT.

[0024] The process of fitting an exponential curve to the data points is a form of statistical regression. However, unlike linear regression or higher-order polynomial regression, an exact formula is not readily derivable. In the present disclosure, an exponential curve of the form f(x) = A + Be is continuously fitted. Cx designed to fit the provided data points using regression and approximation. The initial approximate values for parameters A, B, and C can be determined by linear approximation. However, for a near-exact fit to the data points required by this process, the exponential curve is further tuned by iteratively adjusting the parameters to minimize the error between the model and the data points.

[0025] Instead of using data from a single point to determine the next measurement point, the present disclosure includes a search function that uses multiple data points to model the device, increasing accuracy. Because the model described in the present disclosure is a continuous function, the next measurement can be taken at any value and is not limited to a discrete list of possible values, as was the case with a binary search. This increase in accuracy also reduces the number of measurement iterations required to reach the target point for the parameter. While the present disclosure refers to a continuous function, it can also be applied to other types of functions.

[0026] Because a curve requires three points, the search function of the present disclosure treats the first three measurement points as in a binary search function. Then, an exponential curve is fitted to the data. The curve is used to determine the fourth measurement point. The measurement value lies within the general range of the target value. To make the closest approximation to the target value as accurate as possible, only the three closest data pairs are used to construct the curve, so that the approximation is limited to the target range. This process is iterative: measuring closer to the target, building a model of the local data points, and measuring again until sufficiently close to the target.

[0027] As previously mentioned, a DUT (e.g., DUT 124) may be connected to a test and measurement instrument (e.g., test and measurement instrument 102) for testing. Before the test and measurement instrument takes a measurement, the test and measurement instrument does not have any information about the DUT. In some examples, the test and measurement instrument may have information from the user regarding the DUT, such as the DUT's device type (e.g., diode, MOSFET). In some examples, the test and measurement instrument may have the desired property and / or parameter to be measured for the DUT. For example, the user may want to determine the Vgs threshold for the MOSFET if the DUT is a diode. Accordingly, some information about the DUT is unknown to the test and measurement instrument, and the user wants to determine the information about the DUT using the test and measurement instrument.Accordingly, the test and measurement instrument requires further information about the desired characteristics and / or parameters of the DUT to perform further testing of the DUT. However, once the test and measurement instrument has obtained the information about the desired characteristic and / or parameter of the DUT, the test and measurement instrument adapts its behavior to continue testing the DUT based on the desired characteristic and / or parameter and based on the model of the desired characteristic and / or parameter.

[0028] Since the test and measurement instrument does not have any information about the property and / or parameter of the DUT, the test and measurement instrument starts by determining the property and / or parameter of the DUT using the search function described here (e.g., search function 128 of Fig. 1). The test and measurement instrument begins the search function by taking three measurements for the desired device characteristic and / or parameter. For each of the three measurements, the test and measurement instrument performs the search function by searching for a specific device characteristic and / or parameter based on a desired result within a lower limit and an upper limit from a previous measurement iteration. In some examples, the test and measurement instrument determines that the test and measurement instrument has not taken a previous measurement and therefore uses a predetermined lower limit and upper limit. In some examples, the lower and upper limits can be set by the user before starting the search function.

[0029] Fig. 2-6 illustrate the parameters for measurements to characterize a device using the search function described herein, according to some examples. For example, when performing the search function of the present disclosure for an example device, e.g., a diode, the search function looks for a first measurement of the voltage between 0.00 volts (i.e., the lower limit) and 1.00 volts (i.e., the upper limit) such that the diode conducts 10 mA. Accordingly, for Measurement 1 of the search function of the present disclosure, the search function uses a source voltage of 500 mV via the test and measurement instrument, resulting in a measured current of 0.503 mA.

[0030] Because the first measurement results in a different result than the desired one, the test and measurement instrument adjusts the lower and upper limits for the next measurement based on the previous measurement. For example, because the measured current of measurement 1 was less than the target current of 10 mA, the test and measurement instrument determines that the required voltage is greater than 500 mV and less than 1.00 V, as shown on the X-axis in Fig. 2, i.e., the resolution is 500 mV. Accordingly, the test and measurement instrument sets the lower limit of the next measurement to 500 mV and the upper limit of the next measurement to 1.00 V.

[0031] The test and measurement instrument sets the source voltage of the next measurement to a midpoint or 750 mV between the set lower limit and upper limit of the next measurement. Accordingly, Measurement 2 of the search function of the present disclosure uses a source voltage of 750 mV, resulting in a measured current of 121 mA.

[0032] Since measurement 2 still produces different results than desired, the test and measurement instrument adjusts the lower and upper limits for the next measurement based on the previous measurement. Since the measured current of measurement 2 was greater than the target current of 10 mA, the required voltage is greater than 500 mV and less than 750 mV, as shown on the X-axis of Fig. 3, i.e., the resolution is set to 250 mV or half of the previous 500 mV. Accordingly, the test and measurement instrument sets the lower limit of the next measurement to 500 mV and the upper limit of the next measurement to 750 mV, as shown in Fig. 3 shown.

[0033] The test and measurement instrument adjusts the source voltage of the next measurement to the midpoint, or 625 mV, between the adjusted lower limit and upper limit of the next measurement. Accordingly, Measurement 3 of the search function of the present disclosure uses a source voltage of 625 mV, resulting in a measured current of 8.5 mA.

[0034] Since the search function of the present disclosure has three data points at this time, a curve can be fitted to the three data points. Accordingly, the test and measurement instrument determines a model based on the three data points (e.g., Measurement 1, Measurement 2, and Measurement 3). In some examples, the model is an exponential function model. In other examples, the exponential function is based on f(x) = A + Be Cx . Accordingly, the test and measurement instrument determines the model so that the exponential model fits the provided data points using regression and approximation. In such examples, the test and measurement instrument determines the coefficients A, B, and C for the exponential function.

[0035] To verify the accuracy of the model, the test and measurement instrument performs further measurements. Since the third measurement still yields different results than desired, the test and measurement instrument adjusts the lower and upper limits for the next measurement based on the previous measurement. Since the current measured in measurement 3 was below the target current of 10 mA, the required voltage is greater than 625 mV and less than 750 mV, as shown on the x-axis of Fig. 4, that is, the resolution is set to 125 mV, or half of the previous 250 mV. Accordingly, the test and measurement instrument sets the lower limit of the next measurement to 625 mV and the upper limit of the next measurement to 750 mV.

[0036] The test and measurement instrument sets the source voltage of the next measurement to a point between the adjusted lower limit and upper limit of the next measurement. At this point, the test and measurement instrument uses a different resolution for the next measurement than for the three previous measurements. In some examples, the test and measurement instrument uses a resolution to determine the next measurement point that is based on the resolution of the test and measurement instrument. Accordingly, based on the above example, using three points and a linear approximation, the next measurement point can be approximated to 632.6 mV (shown as a black circle) for a desired current of 10 mA based on the exponential model and the resolution of the test and measurement instrument, as shown in Fig. 5. The search function of the present disclosure performs measurement 4 with a source voltage of 632.58 mV, resulting in a measured current of 9.79 mA.

[0037] The test and measurement instrument uses the results of measurement 4 to further fine-tune the exponential curve to match the current results of the search function. In some examples, the test and measurement instrument adjusts the values of A, B, and C for the exponential formula f(x) = A + Be Cxto account for measurement 4. Accordingly, the test and measurement instrument adapts the device parameter model to the measurements performed so far. For example, the test and measurement instrument is looking for the threshold voltage (Vth), which is an example device parameter for a transistor, and therefore the model describes the measured drain current (Ids) of the device as a function of the gate-to-source voltage (Vgs). In this example, the threshold voltage is the amount of Vgs applied to obtain a particular Ids such that the device is considered "on" and conducting. Accordingly, the model representing Ids as a function of Vgs is used to find the threshold voltage for a particular Ids, and thus the test and measurement instrument adapts the model representing Ids as a function of Vgs.Consequently, the test and measurement instrument can use the model to accurately determine the desired device parameter (Vth in this example) and change its behavior based on the model.

[0038] As described, after an initial verification measurement, the test and measurement instrument determines whether or not to continue the search. In some examples, the test and measurement instrument may make the decision whether to continue the search based on the difference between the last measurement and the desired target value. For example, the test and measurement instrument determines that the difference between the measured current of 9.79 mA for measurement 4 and the target current of 10 mA is 0.21 mA. In some examples, the difference threshold for continuing the search may be predefined or user-set.

[0039] In this example, the test and measurement instrument decides to continue the search because the difference between the measured current and the target current is 0.21 mA, which is above the difference threshold for the model, and further verification of the model is required to ensure the model's accuracy. Accordingly, the search function searches for a different value for the source voltage that results in the target current of 10 mA. Because the previous measurement still produces different results than desired, the test and measurement instrument adjusts the lower and upper limits for a next measurement based on the previous measurement. As with the previous measurement, the test and measurement instrument uses a resolution to determine the next measurement point that is based on the resolution of the test and measurement instrument.Since the measured current of measurement 4 was less than the target current of 10 mA, the required voltage is greater than 632.58 mV and less than 750 mV.

[0040] Accordingly, based on the above example, the nearest measurement point for a desired current of 10 mA can be approximated to 633.8 (shown as a black circle) based on the exponential model and the resolution of the test and measurement instrument, as shown in Fig. 6. The search function performs measurement 5 with a source voltage of 633.8 mV, resulting in a measured current of 10.017 mA.

[0041] As described, at each iteration of the search function, the test and measurement instrument determines whether or not to continue the search. With a target current of 10 mA and a reading of 10.017 mA, the search function has an error of only 17 µA on its fifth iteration. While a further iteration of the search function of the present disclosure may produce a measurement numerically closer to the target value, it is important to consider the accuracy of the instrument itself. In the 100 mA range, the test and measurement instrument used to perform these measurements has a current measurement accuracy of 12 µA (with a reading of approximately 10 mA).

[0042] In this example, since the measured current in measurement 5 was greater than the target current of 10 mA, the search function uses the results of measurement 5 to further tune the exponential curve to match the current results of the search function. Accordingly, the search function can perform another measurement based on the exponential model and the resolution of the test and measurement instrument. In this case, measurement 6 uses a source voltage of 633.53 mV, resulting in a measured current of 9.997 mA.

[0043] The adjustment of 0.270 mV between measurement 5 and measurement 6 can be freely compared with the resolution of 16.25 mV achieved by a binary search in the sixth iteration.

[0044] Fig. Figure 7 is a flowchart of a process 700 of the search function described herein, according to some examples. The process 700 may be performed by a test and measurement instrument (e.g., the test and measurement instrument 102 of Fig. 1) are carried out.

[0045] Process 700 begins at 702. Process 700 includes operation 704, which determines three measurements. In some examples, the test and measurement instrument selects a measurement point between a predetermined upper limit and a predetermined lower limit for the first measurement. In such examples, the predetermined upper limit and the predetermined lower limit are user-specified or may be based on the limits of the DUT. In some examples, the test and measurement instrument selects a measurement point between an upper limit based on the previous measurement and a lower limit based on the previous measurement. Because the test and measurement instrument has not yet taken a previous measurement, it may use a lower and an upper limit for a first measurement point that are specified by the limits of the DUT.For example, the test and measurement instrument is looking for a threshold voltage for a transistor, and as such, the first measurement point uses a lower limit of 0 V and an upper limit of 1 V. The three measurements taken during operation 704 can be used to determine any property and / or parameter of the DUT, as long as the measurements taken by the test and measurement instrument on the DUT are aligned with the same property and / or parameter.

[0046] Process 700 includes operation 706, which involves determining the model for the device parameter based on the three measurements. As previously mentioned, in determining the model for the device characteristic and / or the device parameter, the test and measurement instrument uses the three measurements to generate a continuous function representing the operation of the DUT. In some examples, the model is based on an exponential function representing the device characteristic and / or the device parameter of the DUT. The exponential function may have the formula f(x) = A + Be Cx In such examples, the test and measurement instrument can determine the values of A, B and C

[0047] Process 700 includes operation 708, which involves determining a fourth measurement for the device parameter. As previously mentioned, the fourth measurement adjusts the variables for the device characteristic and / or parameter used in the three measurements of operation 704. In some examples, the test and measurement instrument selects a measurement point based on the resolution of the test and measurement instrument. The resolution of the test and measurement instrument may be defined, for example, by the current measurement accuracy specification. In further examples, the test and measurement instrument selects a measurement point between an upper limit based on the previous measurement and a lower limit based on the previous measurement.

[0048] Process 700 includes operation 710, which fits the model for the device parameter based on the available measurements. In some examples, the test and measurement instrument may determine the values of A, B, and C from the formula f(x) = A + Be Cxfor the model representing the device characteristics and / or device parameters. In some examples, before fitting the model, the test and measurement instrument determines whether the fourth measurement deviates too much from the model. In such examples, the model has an expected range of deviation for the measurements of the device parameter. If the test and measurement instrument determines that the fourth measurement deviates from the model by more than a certain amount, the test and measurement instrument takes another measurement, which may be a repeat of the fourth measurement, and if this repeat measurement still deviates from the model by more than the certain amount, the test and measurement instrument indicates an error to the user.

[0049] Process 700 includes operation 712, which determines whether to continue searching for the device parameter. If the test and measurement instrument decides not to continue searching for the device parameter, process 700 proceeds to operation 726.

[0050] If the test and measurement instrument decides to continue searching for the device parameter, process 700 continues to determine a fifth measurement for the device parameter at 714. In some examples, the test and measurement instrument selects a measurement point based on the resolution of the test and measurement instrument. In further examples, the test and measurement instrument selects a measurement point between an upper limit based on the previous measurement and a lower limit based on the previous measurement.

[0051] Process 700 continues with operation 716, which involves fitting the model for the device parameters based on the available measurements. In some examples, operation 716 is similar to operation 710 with the model fitting for device parameters based on the available measurements, including the fifth measurement obtained in operation 714. The test and measurement instrument may determine the values of A, B, and C from the formula f(x) = A + Be Cxfor the model representing the device characteristics and / or device parameters. In some examples, before fitting the model, the test and measurement instrument determines whether the fifth measurement deviates too much from the model. In such examples, the model has an expected range of deviation for the measurements of the device parameter. If the test and measurement instrument determines that the fifth measurement deviates from the model by more than a certain amount, the test and measurement instrument takes another measurement, which may be a repeat of the fifth measurement, and if this repeat measurement still deviates from the model by more than the certain amount, the test and measurement instrument indicates an error to the user.

[0052] Process 700 proceeds to operation 718, where a determination is made as to whether to continue searching for the device parameter. If the test and measurement instrument decides not to continue searching for the device parameter, process 700 proceeds to operation 726.

[0053] If the test and measurement instrument decides to continue searching for the device parameter, process 700 continues to determine another measurement for the device parameter at 720. In some examples, the test and measurement instrument selects a measurement point based on the resolution of the test and measurement instrument. In further examples, the test and measurement instrument selects a measurement point between an upper limit based on the previous measurement and a lower limit based on the previous measurement.

[0054] Process 700 continues with operation 722, which involves fitting the model for the device parameters based on the available measurements. In some examples, operation 722 is similar to operation 710 and operation 716, with the model for device parameters being fitted based on the available measurements, including the last measurement obtained in operation 720. The test and measurement instrument may determine the values of A, B, and C from the formula f(x) = A + Be Cxfor the model representing the device characteristics and / or device parameters. In some examples, before fitting the model, the test and measurement instrument determines whether the most recent measurement deviates too much from the model. In such examples, the model has an expected range of deviation for the measurements of the device parameter. If the test and measurement instrument determines that the most recent measurement deviates from the model by more than a certain amount, the test and measurement instrument takes another measurement, which may be a repeat of the last measurement, and if this re-measurement still deviates from the model by more than the certain amount, the test and measurement instrument indicates an error to the user.

[0055] Process 700 proceeds to operation 724, which determines whether to continue searching for the device parameter. If the test and measurement instrument decides not to continue searching for the device parameter, process 700 proceeds to operation 726.

[0056] If the test and measurement instrument decides to continue searching for the device parameter, process 700 repeats operations 720, 722, and 724 as described above.

[0057] Process 700 includes operation 726, which involves adapting the behavior of the test and measurement instrument based on the model for the device parameter. In some examples, the test and measurement instrument considers the model for the device parameter when performing further measurements, taking measurements for another parameter of the DUT, or analyzing the model for additional information about the DUT.

[0058] In some examples, when deciding whether to continue the search, the test and measurement instrument may determine whether the most recent measurement for the characteristic and / or parameter deviates from the model for the characteristic and / or parameter by a specified amount. The amount of deviation of the measurement from the model may be pre-trained or based on the model. In some examples, the model-based deviation amount may be based on an expected range specified by the model within which the measurement should fall. If the measured value falls outside the expected range specified by the model, subsequently adjusting the model based on the measured value may result in model inversion, which is undesirable.In some examples, once the test and measurement instrument determines that the last measurement deviates from the model by a certain amount without adjusting the model, it performs another measurement. If this new measurement still deviates from the model, the test and measurement instrument indicates an error. In some examples, the deviation between the measurement and the model may apply to every measurement by the test and measurement instrument after the test and measurement instrument has created the model.

[0059] Using a continuous function to determine a measurement allows the measurement to be taken at any value within a continuous range, rather than from a discrete list of predefined values as with binary search. Using a continuous range of values increases accuracy by measuring as close to the target as possible, rather than just the nearest value in the discrete list.

[0060] The use of a binary search and its discrete list of values also leads to quantization error. This quantization error occurs when a measurement is close to the target value and noise determines whether the independent value is incremented or decremented. This quantization error manifests itself in the data as multimodal distributions, indicating a process problem, even though it is only an algorithmic one. The error could be corrected by a more accurate and continuously evaluated algorithm that improves precision.

[0061] The accuracy of a source measurement unit (SMU) is highest when the measurement is performed in the smallest possible range. Since a binary search does not approximate the closest measurement, the SMU cannot set the most optimal range but must select the highest possible range. In comparison, the search function of the present disclosure can make optimal use of the measurement instrument by adaptively setting the range for the highest accuracy.

[0062] If a measurement results in a value that deviates significantly from the model, the search function of the present disclosure may determine that a measurement should be retaken or ultimately return an error indicating that the circuit connection is compromised. Because a binary search relies on a measurement, a binary search would continue to fit the independent variable and return an erroneous value.

[0063] Typically, device modeling during design is done using fully measured parameters to anticipate the device's behavior in the designed circuits. Furthermore, the approximations made during design are typically linear, quadratic, or polynomial and limited to the range in which the device is intended to operate. Using an exponential function better matches the overall behavior of these devices, which is important for a search function that cannot rely on exact behavior.

[0064] The present disclosure involves the iterative use of exponential regression on the instrument using preliminary measurements to further refine a device model used to determine the target measurement, thereby improving the overall accuracy of the search function and precision and reducing the number of measurements. Furthermore, refining the device model to determine the target measurement allows for adjusting the behavior of the test and measurement instrument so that further measurements by the test and measurement instrument are more accurate and precise.

[0065] In this disclosure, the singular forms "a," "an," and "the" include the plural unless the context dictates otherwise. The term "or" is intended to be all-inclusive and means either one, several, or all of the items listed. The terms "comprises," "containing," "includes," "including," or other variations thereof are intended to cover non-exclusive inclusion, such that a process, procedure, or product comprising a list of items does not necessarily include only those items, but may also include other items not expressly listed or inherent in such process, procedure, item, or device. Relative terms such as "about," "approximately," "substantially," and "generally" are used to indicate a possible deviation of ±10% of a stated or understood value.

[0066] The aspects of the present disclosure are intended to be susceptible to various modifications and alternative forms. Specific aspects are illustrated by way of example in the drawings and are described in detail herein. It should be understood, however, that the examples disclosed herein are provided for clarity of discussion and are not intended to limit the scope of the general concepts disclosed herein to the specific aspects described herein, unless expressly limited. As such, the present disclosure is intended to cover all modifications, equivalents, and alternatives to the described aspects in light of the accompanying drawings and claims.

[0067] References in the description to aspects, examples, etc. mean that the subject matter described may have a particular feature, structure, or property. However, not every disclosed aspect may or may not include that particular feature, structure, or property. Furthermore, such expressions do not necessarily refer to the same aspect unless expressly noted. If the discussion describes a particular feature, structure, or property in connection with a particular aspect, that feature, structure, or property may be used in connection with another disclosed aspect, whether or not that feature is expressly described in connection with that other disclosed aspect.

[0068] Aspects of the disclosure may operate on specially designed hardware, firmware, digital signal processors, or on a specially programmed general-purpose computer with a processor that operates according to programmed instructions. As used herein, the terms controller or processor include microprocessors, microcomputers, application-specific integrated circuits (ASICs), cloud-based servers, and special-purpose hardware controllers. One or more aspects of the disclosure may be embodied in computer-usable data and computer-executable instructions, such as one or more program modules executed by one or more computers (including supervisory modules) or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc.that perform specific tasks or implement specific abstract data types when executed by a processor in a computer or other device. The computer-executable instructions may be stored on a non-transitory, computer-readable medium such as a hard disk, an optical disk, a removable storage device, solid-state storage, random access memory (RAM), etc. As will be apparent to those skilled in the art, the functionality of the program modules may be arbitrarily combined or distributed in various aspects. Furthermore, the functionality may comprise, in whole or in part, firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGAs), and the like.Certain data structures may be used to more effectively implement one or more aspects of the disclosure, and such data structures are contemplated as part of the computer-executable instructions and computer-usable data described herein.

[0069] The disclosed aspects may, in some cases, be implemented in hardware, firmware, software, or a combination thereof. The disclosed aspects may also be implemented in the form of instructions stored on one or more non-transferable computer-readable media that can be read and executed by one or more processors. Such instructions may be referred to as a computer program product. Computer-readable media, as described herein, is any media accessible by a computer. Computer-readable media may include, for example, but is not limited to, computer storage media and communications media.

[0070] Computer storage media is any media capable of storing computer-readable information. Examples of computer storage media include RAM, ROM, EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory or other storage technologies, CD-ROM (Compact Disc Read-Only Memory), DVD (Digital Video Disc) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage media, and any other volatile or non-volatile, removable or non-removable media employed in any technology. Computer storage media excludes signals as such and transient forms of signal transmission.

[0071] Communication media is any medium capable of transmitting computer-readable information. Examples of communication media include coaxial cable, fiber optic cable, air, or any other medium suitable for transmitting electrical, optical, radio frequency (RF), infrared, acoustic, or other signals.

[0072] The disclosed aspects may, in some cases, be implemented in hardware, firmware, software, or any combination thereof. The above references to FPGAs and other integrated circuits such as voltage regulators, etc., may be replaced by any component capable of performing the same functions. The disclosed aspects may also be implemented in the form of instructions stored on one or more non-transitory computer-readable media that can be read and executed by one or more processors. Such instructions may be referred to as a computer program product. Computer-readable media, as described herein, is any media accessible by a computer. Computer-readable media may include, for example, but is not limited to, computer storage media and communications media.

[0073] Although this application refers to a method comprising two or more defined steps or operations, the defined steps or operations may be performed in any order or simultaneously, unless the context precludes such possibilities.

[0074] Although certain aspects of the disclosure have been shown and described for purposes of illustration, various changes may be made without departing from the spirit and scope of the disclosure. Accordingly, the disclosure should not be limited except by the appended claims. EXAMPLES

[0075] Examples of the disclosed technologies are listed below. An embodiment of the technologies may include one or more, and any combination, of the examples described below.

[0076] Example 1 is a method for determining a characteristic of a device under test (DUT) coupled to a test and measurement instrument, the method comprising: acquiring a first plurality of measurements for the DUT, wherein the test and measurement instrument is not configured with the characteristic of the DUT and may include the first plurality of measurements for the characteristic; determining an exponential model of the DUT based on the first plurality of measurements, wherein the exponential model is representative of the behavior of the DUT; acquiring a second plurality of measurements different from the first plurality of measurements, wherein the second plurality of measurements may include measurements for the characteristic of the DUT; verifying the exponential model based on the second plurality of measurements; and adjusting the behavior of the test and measurement instrument based on the verified exponential model of the DUT.

[0077] Example 2 is the procedure of Example 1, where the exponential model is based on the following equation: f(x) = A + Be Cx

[0078] Example 3 is the method of Example 2, wherein A, B, and C are determined based on the first plurality of measurements.

[0079] Example 4 is the method of any of Examples 1-3, where the exponential model is a continuous function.

[0080] Example 5 is the method of any one of Examples 1-4, wherein the first plurality of measurements may include current measurements each associated with a corresponding voltage measurement.

[0081] Example 6 is the method of any one of Examples 1-5, wherein the second plurality of measurements has a resolution based on the test and measurement instrument.

[0082] Example 7 is the method of any one of Examples 1 to 6, wherein acquiring the second plurality of measurements includes an iterative measurement at a point based on the resolution of the test and measurement instrument.

[0083] Example 8 is the method of any one of Examples 1-7, wherein acquiring the second plurality of measurements includes determining the point to be measured based on the exponential model.

[0084] Example 9 is the method of any one of Examples 1-8, wherein acquiring the first plurality of measurements includes an iterative measurement at a midpoint between a lower and an upper boundary.

[0085] Example 10 is the method of any of Examples 1-9, where each iteration halves the resolution of a previous measurement.

[0086] Example 11 is the method of any of Examples 1-10, wherein verifying the second plurality of measurements against the exponential model may comprise: determining that at least one of the second plurality of measurements deviates from the exponential model by an amount based on the exponential model; acquiring a third set of measurements; and if the third set of measurements deviates from the exponential model by a deviation amount, indicating an error to a user.

[0087] Example 12 is a test and measurement system comprising: a test and measurement instrument having one or more connectors for connecting the test and measurement instrument to a device under test (DUT). The test and measurement system includes memory.The test and measurement system includes one or more processors configured to execute code stored in memory, the code causing the one or more processors to: acquire a first plurality of measurements for a parameter of the DUT, wherein the test and measurement instrument is not configured with the parameter of the DUT; determine an exponential model of the parameter of the DUT based on the first plurality of measurements; acquire a second plurality of measurements for the parameter of the DUT, wherein the second plurality of measurements are different from the first plurality of measurements; verify the exponential model based on the second plurality of measurements; and adjust the behavior of the test and measurement instrument based on the verified exponential model of the DUT.

[0088] Example 13 is the test and measurement system of Example 12, wherein the second plurality of measurements has a resolution based on the test and measurement instrument.

[0089] Example 14 is the test and measurement system of Example 12 or Example 13, wherein the code that causes the one or more processors to collect the second plurality of measurements may include code that causes the one or more processors to iteratively measure at a point based on the resolution of the test and measurement instrument.

[0090] Example 15 is the test and measurement system of any of Examples 12-14, wherein the code that causes the one or more processors to collect the second plurality of measurements may include code that causes the one or more processors to determine the point to be measured based on the exponential model.

[0091] Example 16 is the test and measurement system of any of Examples 12-15, wherein the code that causes the one or more processors to collect the first plurality of measurements may include code that causes the one or more processors to iteratively measure at a midpoint between a lower bound and an upper bound.

[0092] Example 17 is the test and measurement system from one of Examples 12-16, where each iteration halves the resolution of a previous measurement.

[0093] Example 18 is a test and measurement system comprising: a test and measurement instrument having one or more connectors to connect the test and measurement instrument to a device under test (DUT). The test and measurement system includes memory. The test and measurement system includes one or more processors configured to execute code stored in the memory, the code causing the one or more processors to: determine a model of a parameter of the DUT based on three measurements of the parameter by the test and measurement instrument; verify the model based on a fourth measurement and a fifth measurement of the parameter by the test and measurement instrument; and adjust the behavior of the test and measurement instrument for the parameter based on the verified model of the DUT.

[0094] Example 19 is the test and measurement system of Example 18, wherein the code that causes the one or more processors to collect the fourth and fifth measurements may include code that causes the one or more processors to iteratively measure at a point based on a resolution of the test and measurement instrument.

[0095] Example 20 is the test and measurement system of Example 18 or Example 19, where the model is based on the following equation: f(x) = A + Be Cx .

[0096] The previously described versions of the disclosed subject matter have many advantages that have either been described or are obvious to a person of ordinary skill. Nevertheless, these advantages or features are not required in all versions of the disclosed devices, systems, or methods.

[0097] Furthermore, this written description refers to specific features. It is understood that the disclosure in this specification encompasses all possible combinations of these particular features. Where a particular feature is disclosed in connection with a particular aspect or example, that feature may, where possible, also be used in connection with other aspects and examples.

[0098] Although this application refers to a method comprising two or more defined steps or operations, the defined steps or operations may be performed in any order or simultaneously, unless the context precludes such possibilities.

[0099] Although specific examples of the invention have been shown and described for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention should not be limited except as by the appended claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 620,350

[0001]

Claims

[1] A method for determining a characteristic of a device under test (DUT) coupled to a test and measurement instrument, the method comprising: Acquiring a first plurality of measurements for the DUT, wherein the test and measurement instrument is not configured with the characteristic of the DUT and includes the first plurality of measurements for the characteristic; Determining an exponential model of the DUT based on the first plurality of measurements, the exponential model being representative of the behavior of the DUT; Acquiring a second plurality of measurements different from the first plurality of measurements, the second plurality of measurements comprising measurements for the characteristic of the DUT; Verifying the exponential model based on the second plurality of measurements; and Adjusting the behavior of the test and measurement instrument based on the verified exponential model of the DUT. [2] The method of claim 1, wherein the exponential model is based on the following equation: f(x) = A + Be Cx . [3] The method of claim 2, wherein A, B and C are determined based on the first plurality of measurements. [4] The method of claim 2 or 3, wherein the exponential model is a continuous function. [5] The method of any one of claims 1 to 4, wherein the first plurality of measurements comprises current measurements each associated with a corresponding voltage measurement. [6] The method of any one of claims 1 to 5, wherein the second plurality of measurements has a resolution based on the test and measurement instrument. [7] The method of claim 6, wherein acquiring the second plurality of measurements includes an iterative measurement at a point based on the resolution of the test and measurement instrument. [8] The method of claim 7, wherein acquiring the second plurality of measurements includes determining the point to be measured based on the exponential model. [9] The method of any one of claims 1 to 8, wherein acquiring the first plurality of measurements includes an iterative measurement at a midpoint between a lower boundary and an upper boundary. [10] The method of claim 9, wherein each iteration halves a resolution of a previous measurement. [11] The method of any one of claims 1 to 10, wherein verifying the second plurality of measurements against the exponential model comprises: determining that at least one of the second plurality of measurements deviates from the exponential model by an amount based on the exponential model; Acquiring a third set of measurements; and indicate an error to the user if the third set of measurements deviates from the exponential model b by a deviation amount. [12] A test and measurement system comprising: a test and measurement instrument having one or more connectors to connect the test and measurement instrument to a device under test (DUT); Memory; one or more processors configured to execute code stored in the memory, the code causing the one or more processors to: Acquiring a first plurality of measurements for a parameter of the DUT, wherein the test and measurement instrument is not configured with the parameter of the DUT; Determining an exponential model of the parameter of the DUT based on the first plurality of measurements; Acquiring a second plurality of measurements for the parameter of the DUT, wherein the second plurality of measurements are different from the first plurality of measurements; Verifying the exponential model based on the second plurality of measurements; and Adjusting the behavior of the test and measurement instrument based on the verified exponential model of the DUT. [13] The test and measurement system of claim 12, wherein the second plurality of measurements have a resolution based on the test and measurement instrument. [14] The test and measurement system of claim 13, wherein the code that causes the one or more processors to acquire the second plurality of measurements comprises code that causes the one or more processors to iteratively measure at a point based on the resolution of the test and measurement instrument. [15] The test and measurement system of claim 14, wherein the code that causes the one or more processors to acquire the second plurality of measurements comprises code that causes the one or more processors to determine the point to be measured based on the exponential model. [16] The test and measurement system of any one of claims 12 to 15, wherein the code that causes the one or more processors to collect the first plurality of measurements comprises code that causes the one or more processors to iteratively measure at a midpoint between a lower bound and an upper bound. [17] The test and measurement system of claim 16, wherein each iteration halves a resolution of a previous measurement. [18] A test and measurement system comprising: a test and measurement instrument having one or more connectors to connect the test and measurement instrument to a device under test (DUT); Memory; one or more processors configured to execute code stored in the memory, the code causing the one or more processors to: Determining a model of a parameter of the DUT based on three measurements of the parameter by the test and measurement instrument; Verifying the model based on a fourth measurement and a fifth measurement of the parameter by the test and measurement instrument; and Adjust the behavior of the test and measurement instrument for the parameter based on the verified model of the DUT. [19] The test and measurement system of claim 18, wherein the code that causes the one or more processors to acquire the fourth and fifth measurements comprises code that causes the one or more processors to iteratively measure at a point based on a resolution of the test and measurement instrument. [20] The test and measurement system according to claim 18 or 19, wherein the model is based on the following equation: f(x) = A + Be Cx

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