Calibration method and calibration system

Abstract

The invention discloses a calibration method and a calibration system. A calibration method for calibrating a test instrument comprising at least one port, at least one signal analysis module and at least one signal generator module is described. The at least one signal analysis module and the at least one signal generator module are each connected to the at least one port. The calibration method comprises the steps of: successively connecting a set of calibration standards to at least one port, and performing a calibration measurement for each connected calibration standard, thereby obtaining a first set of measurement data; determining a plurality of error terms of the multi-port error model based on the multi-port error model and the first set of measurement data, where at least one of the error terms includes a product of two error parameters; connecting an additional calibration standard to the at least one port; performing a calibration measurement if the additional calibration standard has been connected, thereby obtaining a second set of measurement data; and determining two error parameters based on the second set of measurement data.

Description

Technical Field

[0001] The present invention generally relates to a calibration method for calibrating a test instrument. The present invention also relates to a calibration system. Background Art

[0002] In order to perform accurate measurements on a device under test, a test device including a test instrument must be calibrated to ensure the maximum accuracy of the measurements performed.

[0003] For example, a calibration technique known in the prior art is the so-called OSM calibration, in which three different calibration standards ("open", "short", and "matched") are successively connected to the test instrument, and corresponding reflection measurements are respectively performed. OSM calibration is also referred to as SOL calibration ("short", "open", "load").

[0004] If the test instrument includes more than one port to be connected to the device under test, additional relative measurements between the ports must be performed, for example by adding "through" calibration measurements (TOSM method) or "unknown" calibration measurements (UOSM method). The TOSM method is also referred to as the SOLT method ("short", "open", "load", "through").

[0005] To fully characterize the test instrument, relative measurements must be performed for each pair of ports. Therefore, the number of necessary measurements grows rapidly with the number of ports.

[0006] Therefore, an object of the present invention is to provide a calibration method and system that allow each port to be fully characterized with a reduced number of measurements. Summary of the Invention

[0007] According to the present invention, this problem is solved by a calibration method for calibrating a test instrument. The test instrument includes at least one port, at least one signal analysis module, and at least one signal generator module. The at least one signal analysis module and the at least one signal generator module are each connected to the at least one port. The calibration method includes the following steps:

[0008] - successively connecting a set of calibration standards to the at least one port and performing calibration measurements for each connected calibration standard to obtain a first set of measurement data;

[0009] - determining a plurality of error terms of the multi-port error model based on the multi-port error model and the first set of measurement data, wherein the error terms describe at least the transmissive and reflective characteristics of the at least one port, and wherein at least one of the error terms includes a product of two error parameters;

[0010] - Connect an additional calibration standard to at least one port, wherein the additional calibration standard is a signal source with known characteristics or a signal sink with known characteristics;

[0011] - Perform a calibration measurement with the additional calibration standard connected, thereby obtaining a second set of measurement data; and

[0012] - Determine two error parameters based on the second set of measurement data.

[0013] Herein and hereinafter, the terms "error term" and "error parameter" are understood to represent the parameters of a multi-port error model, which describe the transmissive and reflective characteristics of a part of a measuring device including the ports.

[0014] Furthermore, the term "module" is understood to describe suitable hardware, suitable software, or a combination of hardware and software configured to have a specific functionality.

[0015] The hardware may in particular include a CPU, GPU, FPGA, ASIC, or other types of electronic circuitry.

[0016] Based on the determined error terms and error parameters, the operating parameters of the test instrument can be adjusted, i.e., the test instrument can be calibrated relative to at least one port.

[0017] In fact, the operating parameters can be corrected in the time domain or the frequency domain.

[0018] Using previously known calibration methods, at least one error term including the product of two error parameters can only be determined as a whole, and the individual error parameters cannot be determined based on measurements of at least one port alone.

[0019] The calibration method according to the present invention is based on the idea of providing an additional calibration standard with known characteristics.

[0020] Performing an additional calibration measurement on the additional calibration standard allows the decomposition of the product of two error parameters such that the individual error parameters can be determined.

[0021] This allows the determination of all necessary parameters of the multi-port error model based on measurements of at least one port alone.

[0022] In other words, at least one port of the test instrument can be fully characterized based on measurements of at least one port alone, i.e., independently of the other ports of the test instrument.

[0023] Therefore, if the test instrument includes multiple ports, the number of necessary measurements is reduced.

[0024] However, it should be understood that the calibration method according to the present invention can equally be applied to a test instrument having only one port. In this case, the calibration method according to the present invention allows for a complete characterization of the single port.

[0025] In fact, it has been demonstrated that the calibration method according to the present invention is also suitable for calibrating a vector network analyzer, in particular also for a modulated vector network analyzer.

[0026] The calibration method can include the step of providing a test instrument that includes at least one port, at least one signal analysis module, and at least one signal generator module, wherein at least one signal analysis module and at least one signal generator module are each connected to at least one port.

[0027] Optionally, the calibration method can include the step of connecting at least one signal analysis module and / or at least one signal generator module to at least one port, especially if at least one signal analysis module and / or at least one signal generator module are / is connected to / not connected to at least one port in the initial state of the test instrument.

[0028] According to one aspect of the present invention, a calibration standard is connected to at least one port at a reference plane. Thus, a first set of measurement data and a second set of measurement data are obtained with respect to the reference plane, which can include a connecting member such as a cable between at least one port and the reference plane. Thus, the multi-port error model describes the transmissive and reflective characteristics of a part of the measuring device that includes the port and the reference plane (especially including the cable connecting at least one port to the reference plane).

[0029] In fact, the reference plane can correspond to the plane where the device under test is to be connected to at least one port.

[0030] In an embodiment of the present invention, a cable is connected to at least one port, where the reference plane is located at the end of the cable facing away from at least one port. Thus, the multi-port error model describes the transmissive and reflective characteristics of a part of the measuring device that includes the port, the cable, and the reference plane. In this way, since the connecting member (i.e., the cable) between the test instrument and the device under test is incorporated into the calibration, the accuracy of the calibration (or more precisely, subsequent measurements) of the device under test can be improved.

[0031] According to another aspect of the present invention, the product of two error parameters includes a first error parameter and a second error parameter, wherein the first error parameter is directly determined based on a second set of measurement data, and wherein the second error parameter is calculated based on the determined product of the two error parameters and based on the first error parameter. In other words, since the product of the two error parameters has been determined based on the first set of measurement data, one of the two error parameters can be directly measured, and the other of the two error parameters can then be determined or rather calculated.

[0032] Note that in principle, another known calibration standard can also be used for another measurement such that both error parameters can be directly measured. However, this requires additional measurement steps.

[0033] Another aspect of the present invention provides that the mismatch of an additional calibration standard is corrected based on the first set of measurement data. In fact, the impedance mismatch between the additional calibration standard and the reference plane can be corrected based on the first set of measurement data. Thus, when the mismatch is corrected based on the first set of measurement data, the second set of measurement data can be determined with improved accuracy.

[0034] In another embodiment of the present invention, the test instrument includes at least one directional coupler, wherein at least one signal analysis module and at least one signal generator module are connected to at least one port via at least one directional coupler. More precisely, each port is connected to at least one signal generator module and at least one signal analysis module via at least one directional coupler. In this way, all necessary calibration measurements can be performed on at least one port in a particularly efficient manner independent of other ports.

[0035] The multi-port error model can be an n-term error model, particularly a four-term error model. Thus, the multi-port error model includes n error parameters that need to be determined in order to calibrate the test instrument, i.e., the error terms include a total of n error parameters.

[0036] In which, n is an integer greater than 1, particularly equal to or greater than 4.

[0037] However, it should be understood that any other suitable error model can be used, such as a 12-term error model.

[0038] Specifically, the multi-port error model is a two-port error model. In which, one port of the error model can be associated with the signal generator module or the signal analysis module, and the other port of the error model can be associated with the reference plane. The error model describes the transmissive and reflective characteristics within a part of the test system modeled by the error model (i.e., a part of the test system between the signal generator module or the signal analysis module and the reference plane).

[0039] According to one aspect of the present invention, exactly one port of a calibration test instrument is calibrated at a time. As already explained above, the calibration method according to the present invention allows each port to be calibrated independently of the other ports. Thus, the different ports of the test instrument can be calibrated successively.

[0040] In an embodiment of the present invention, additional calibration standards are established as a signal generator, a comb generator, an oscilloscope, or an analog-to-digital converter. More precisely, the additional calibration standards can be established as a signal generator with known characteristics, a comb generator with known characteristics, an oscilloscope with known characteristics, or an analog-to-digital converter with known characteristics.

[0041] However, it should be understood that any other suitable type of additional calibration standard can be used.

[0042] According to another aspect of the present invention, each calibration standard of a set of calibration standards is arranged in a calibration device having a housing, wherein the calibration device further comprises a switching module and a connection port, and wherein the switching module is configured to selectively connect one of the calibration standards to the connection port. Thus, a particularly convenient way of obtaining a first set of measurement data is provided, because by successively connecting the calibration standards to the connection port via the switching module, the calibration standards can simply be connected to at least one port of the test instrument. Thus, there is no need to change the measuring device for performing calibration measurements on different calibration standards.

[0043] Therein, the connection port can be connected to at least one port of the test instrument, for example, by a cable.

[0044] For example, the set of calibration standards can include three different calibration standards, in particular where the three different calibration standards are arranged in the housing of the calibration device. For example, the three different calibration standards can be "open circuit", "short circuit", and "matched". However, any other suitable set of calibration standards can be used.

[0045] In an embodiment of the present invention, additional calibration standards can be arranged in the housing. The switching module can be configured to selectively connect one of the calibration standards or the additional calibration standards to the connection port. Thus, a particularly convenient way of obtaining a first set of measurement data and a second set of measurement data is provided, because the calibration standards and the additional calibration standards can simply be connected to at least one port of the test instrument by successively connecting the calibration standards to the connection port via the switching module. Thus, there is no need to change the measuring device for performing calibration measurements on different calibration standards and additional calibration standards.

[0046] Alternatively, additional calibration standards can be provided separately from the calibration device, where the calibration device includes additional connection ports, and where the switching module is configured to selectively connect one of the calibration standards or the additional connection ports to the connection ports. Thus, the additional calibration standards provided separately from the calibration device can be connected, for example via a cable, to the additional connection ports such that the switching module can selectively connect one of the calibration standards or the additional calibration standards to the connection ports and thus to the test instrument. If the additional calibration standards generate a large amount of heat, it is particularly advantageous to arrange the additional calibration standards outside the housing of the calibration device.

[0047] Specifically, the test instrument is a vector network analyzer, a signal generator, in particular a vector signal generator, or a signal analyzer, in particular a vector signal analyzer. For example, the test instrument can be a modulated vector network analyzer.

[0048] If the test instrument is a signal analyzer, in particular a vector signal analyzer, the test instrument can still include a signal generator module. The signal generator module can act as an "assistant" module for performing the calibration method described above.

[0049] If the test instrument is a signal generator, in particular a vector signal generator, the test instrument can still include a signal analysis module. The signal analysis module can act as an "assistant" module for performing the calibration method described above.

[0050] However, it should be understood that the calibration method described above can be applied to any other test instrument having at least one port, such as an oscilloscope, a spectrum analyzer, etc.

[0051] According to the invention, the problem is further solved by a calibration system. The calibration system includes a test instrument, a set of calibration standards, and additional calibration standards, where the calibration system is configured to perform the calibration method according to any one of the variants described above.

[0052] Regarding the advantages and additional features of the calibration system, reference is made to the explanations given above with respect to the calibration method, which apply equally to the calibration system and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] When considered in conjunction with the accompanying drawings, the foregoing aspects as well as many attendant advantages of the claimed subject matter will become more readily appreciated and better understood by reference to the following detailed description, in which

[0054] - Figure 1 a first variant of a calibration system according to the invention is schematically illustrated;

[0055] - Figure 2Schematically shows a second variant of the calibration system according to the present invention;

[0056] - Figure 3 Shows a flowchart of the calibration method according to the present invention;

[0057] - Figure 4 Shows a first variant of the multi-port error model; and

[0058] - Figure 5 Shows a second variant of the multi-port error model. DETAILED DESCRIPTION

[0059] The detailed description set forth below in connection with the appended drawings is intended as a description of the various embodiments of the disclosed subject matter and is not intended to represent the only embodiments, where like numerals refer to like elements. Each of the embodiments described in this disclosure is provided merely as an example or illustration and should not be construed as superior or advantageous to other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed.

[0060] For purposes of this disclosure, the phrase "at least one of A, B, and C" means, for example, (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible permutations when listing more than three elements. In other words, the term "at least one of A and B" generally means "A and / or B," i.e., A alone, B alone, or A and B.

[0061] Figure 1 Schematically shows a calibration system 10 for calibrating a test instrument 12.

[0062] In Figure 1 the exemplary embodiment shown, the test instrument 12 may be configured as a vector network analyzer including a first port 14 and a second port 16.

[0063] For example, the test instrument 12 may be a modulated vector network analyzer.

[0064] However, it should be understood that the explanations given below are equally applicable to other types of test instruments that may have the same or different numbers of ports.

[0065] For example, the test instrument 12 may be a signal analyzer, a vector signal analyzer, a signal generator, a vector signal generator, a spectrum analyzer, or an oscilloscope.

[0066] Without loss of generality, the exemplary embodiment of the test instrument 12 shown below is described. Figure 1 the test instrument 12 shown.

[0067] The test instrument 12 includes a signal generator module 18 and a signal analysis module 20.

[0068] The signal generator module 18 is configured to generate a test signal, which can be applied to the device under test via the first port 14.

[0069] Specifically, the signal generator module 18 can be or include a vector signal generator.

[0070] The signal analysis module 20 is configured to receive the corresponding processed signal from the device under test via the second port 16 and analyze the processed signal to evaluate the performance of the device under test.

[0071] Specifically, the signal analysis module 20 can be or include a vector signal analyzer.

[0072] In which, the signal generator module 18 and the signal analysis module 20 are respectively connected to the first port 14 via a first directional coupler 22.

[0073] The first directional coupler 22 is configured to transmit the forward-propagating signal from the signal generator module 18 to the first port 14.

[0074] The first directional coupler 22 is also configured to transmit the backward-propagating signal from the first port 14 to the signal analysis module 20.

[0075] In addition, the signal generator module 18 and the signal analysis module 20 are respectively connected to the second port 16 via a second directional coupler 24.

[0076] The second directional coupler 24 is configured to transmit the forward-propagating signal from the second port 16 to the signal analysis module 20.

[0077] The second directional coupler 24 is also configured to transmit the backward-propagating signal from the signal generator module 18 to the second port 16.

[0078] The test instrument 12 further includes a control module 26, which is configured to control the signal generator module 18 and / or the signal analysis module 20.

[0079] More precisely, the control module 26 can be configured to set the operating parameters of the signal generator module 18 and / or the signal analysis module 20, such as frequency range, bandwidth, sampling rate, filter coefficients, etc.

[0080] The calibration system 10 further includes a calibration device 28 provided separately from the test instrument 12.

[0081] In fact, the calibration device 28 includes a housing 30 established separately from the test instrument 12, and the components described below are arranged in the housing 30.

[0082] The calibration device 28 includes a connection port 32 that can be connected to the first port 14 and / or the second port 16 of the test instrument 12.

[0083] The calibration device 28 further includes a set of calibration standards, and the set of calibration standards includes a first calibration standard 34, a second calibration standard 36, and a third calibration standard 38.

[0084] For example, the first calibration standard 34, the second calibration standard 36, and the third calibration standard 38 can respectively correspond to "open circuit" ("O"), "short circuit" ("S"), and "matched" ("M") calibration standards.

[0085] However, it should be understood that the set of calibration standards can include other suitable types of calibration standards.

[0086] In addition, in Figure 1 the illustrated exemplary embodiment, an additional calibration standard 40 ("A") is arranged within the housing 30.

[0087] Generally, the additional calibration standard 40 is a signal source with known characteristics or a signal sink with known characteristics.

[0088] For example, the additional calibration standard 40 can be established as a signal generator, a comb generator, or an analog-to-digital converter.

[0089] The calibration device 28 further includes a switching module 42 connected to the connection port 32 and the calibration standards 34, 36, 38, 40.

[0090] The switching module 42 is configured to selectively connect one of the calibration standards 34, 36, 38 or the additional calibration standard 40 to the connection port 32.

[0091] Figure 2 A second variant of the calibration system 10 is shown, and only the differences from the first variant described above are illustrated below.

[0092] In Figure 2 the shown variant, the additional calibration standard 40 is arranged separately from the calibration device 28.

[0093] For example, the additional calibration standard 40 can be established as a signal generator, a comb generator, an oscilloscope, or an analog-to-digital converter.

[0094] The calibration device 28 includes an additional connection port 44 connected to the switching module 42.

[0095] The additional connection port 44 can be connected to an additional calibration standard 40, such that the additional calibration standard can be connected to the connection port 32 via the switching module 42 and the additional connection port 44.

[0096] The switching module 42 is configured to selectively connect one of the calibration standards 34, 36, 38 or the additional connection port 44 to the connection port 32.

[0097] Note that the calibration device 28 according to any of the variants described above is optional. Each of the calibration standards 34, 36, 38 and / or the additional calibration standard 40 can also be directly connected to the test instrument 12, i.e., directly via a cable.

[0098] Furthermore, note that the test instrument 12 can include more than one signal generator module, and / or more than one signal analysis module, and / or other numbers of ports.

[0099] In any case, each port is connected to at least one signal generator module, particularly exactly one signal generator module, and is connected to at least one signal analysis module, particularly exactly one signal analysis module.

[0100] Hereinafter, reference Figure 3 describes a calibration method for calibrating the test instrument 12, Figure 3 and shows a flowchart of the calibration method.

[0101] Provide the test instrument 12 described above (step S1).

[0102] Optionally, provide the calibration device 28 described above (step S2).

[0103] Hereinafter, it is assumed without loss of generality that the calibration device 28 is provided. However, it should be understood that the steps described below can also be performed with appropriate adjustments in the absence of the calibration device 28.

[0104] The calibration standards 34, 36, 38 of the set of calibration standards are successively connected to the first port 14 of the test instrument, and corresponding calibration measurements are performed by the signal generator module 18 and the signal analysis module 20 for each of the calibration standards 34, 36, 38 (step S3).

[0105] Specifically, the first calibration measurement is performed with the first calibration standard 34 connected to the first port 14.

[0106] Thereafter, the second calibration measurement is performed with the second calibration standard 36 connected to the first port 14.

[0107] Finally, the third calibration measurement is performed with the third calibration standard 38 connected to the first port 14.

[0108] In fact, the calibration measurement performed can be a reflection measurement, i.e., the test signal is generated by the signal generator module 18 and is forwarded via the first port 14, the connection port 32, and the switching module 42 to the respective calibration standards 34, 36, 38.

[0109] The signals reflected by the respective calibration standards 34, 36, 38 are forwarded via the switching module 42, the connection port 32, the first port 14, and the first directional coupler 22 to the signal analysis module 20.

[0110] The signal analysis module 20 analyzes the respective reflected signals, thereby obtaining a first set of measurement data.

[0111] In fact, the first set of measurement data includes measurement data regarding each of the calibration standards 34, 36, 38.

[0112] It should be noted that it is not necessary to start the calibration of the test instrument 12 using the first port 14. Similarly, the calibration can be performed first on the second port 16 or other ports of the test instrument 12.

[0113] The signal analysis module 20 determines a plurality of error terms of the multi-port error model based on the multi-port error model and based on the first set of measurement data (step S4).

[0114] Generally, the error terms of the multi-port error model describe the transmissive and reflective characteristics of at least one respective port (i.e., the first port 14 in the case described above).

[0115] More precisely, the multi-port error model includes error terms that describe the transmissive and reflective characteristics, where each of the error terms includes one or more error parameters.

[0116] Figure 4 An exemplary multi-port error model is shown. In this exemplary case, the multi-port error model is a 2-port error model with four error parameters e 00 、e 10 、e 01 and e 11 .

[0117] However, it should be understood that any other suitable multi-port error model can be used. In fact, the multi-port error model can be any suitable n-term error model including n error parameters.

[0118] Figure 4The error model describes a part of the calibration system 10 between the signal generator module 18 and the reference plane 46.

[0119] As Figure 4 shown, the reference plane 46 is located at the point where the device under test (DUT) 48 is to be connected to the first port 14.

[0120] During calibration, the calibration device 28 is connected to the first port 14 at the reference plane 46.

[0121] Thus, the reference plane 46 can be at the end of the cable connecting the first port 14 and the calibration device 28, that is, at the end of the cable away from the first port 14.

[0122] Four error parameters e 00 、e 10 、e 01 and e 11 describe the transmission between the signal generator module 18 and the signal analysis module 20, the transmission between the signal generator module 18 and the reference plane 46, the transmission between the reference plane 46 and the signal analysis module 20, and the reflection at the reference plane 46, respectively.

[0123] This multi-port error model can be expressed as a matrix

[0124] In this example, the error terms e 00 、e 10 、e 01 and e 11 can be determined based on a first set of measurement data, that is, one of the determined error terms includes the product of two error parameters that cannot be determined separately based on the first set of measurement data.

[0125] An additional calibration standard 40 is connected to the first port 14, and additional calibration measurements are performed by the signal generator module 18 and the signal analysis module 20 with the additional calibration standard 40 connected to the first port 14, thereby obtaining a second set of measurement data (step S5).

[0126] In fact, the mismatch of the additional calibration standard 40 can be corrected based on the first set of measurement data for determining the second set of measurement data.

[0127] More precisely, the impedance mismatch between the additional calibration standard 40 and the reference plane 46 can be corrected based on the first set of measurement data for determining the second set of measurement data.

[0128] The error parameters included in the product of the error parameters are determined by the signal analysis module 20 based on the second set of measurement data (step S6).

[0129] More precisely, one of the two error parameters included in the product of the error parameters is directly determined based on the second set of measurement data, i.e., one of the two error parameters is directly measured.

[0130] The other of the two error parameters can then be calculated based on the determined product and the measured error parameter of the product.

[0131] In the exemplary multi-port error model described above, if the additional calibration standard is a signal source, the error parameter e 01 can be directly measured, and the error parameter e 10 can then be calculated.

[0132] If the additional calibration standard is a signal sink, the error parameter e 10 can be directly measured, and the error parameter e 01 can then be calculated.

[0133] Thus, all the error parameters of the multi-port error model are determined based on measurements performed only with respect to the first port 14.

[0134] The control module 26 adjusts the operating parameters of the test instrument 12 based on the determined error parameters, in particular the operating parameters of the signal generator module 18 and / or the signal analysis module 20 (step S7).

[0135] Thus, the test instrument 12 is calibrated with respect to the first port 14 based on the determined error parameters.

[0136] In this, the calibration can be performed in the time domain or the frequency domain.

[0137] Then, the above-described steps S3 to S7 are repeated for the second port 16 (step S8).

[0138] Figure 5 A multi-port error model for calibrating the second port 16 is shown, and the multi-port error model is established similarly to the multi-port error model for calibrating the first port 14 described above.

[0139] The four error parameters e 00 、e 10 、e 01 and e 11 describe the transmission between the signal generator module 18 and the signal analysis module 20, the transmission between the reference plane 46 and the signal analysis module 20, the transmission between the signal generator module 18 and the reference plane 46, and the reflection at the reference plane 46, respectively.

[0140] The multi-port error model can be expressed as a matrix

[0141] If the test instrument 12 includes additional ports, the additional ports can be calibrated successively, i.e., one port can be fully calibrated at a time.

[0142] Thus, the calibration method described above enables full calibration of all ports of the test instrument 12, where each port can be calibrated independently of any other port.

[0143] The specific embodiments disclosed herein, particularly the corresponding module(s) and / or unit(s), utilize circuitry (e.g., one or more circuits) to implement the standards, protocols, methods, or techniques disclosed herein, operably couple two or more components, generate information, process information, analyze information, generate signals, encode / decode signals, convert signals, transmit and / or receive signals, control other devices, etc. Any type of circuitry may be used.

[0144] In embodiments, among other things, the circuitry includes one or more computing devices such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a system on a chip (SoC), or the like, or any combination thereof; and may include discrete digital or analog circuit elements or electronic devices, or a combination thereof. In embodiments, the circuitry includes hardware circuit implementations (e.g., implementations in analog circuitry, digital circuitry, and the like, and combinations thereof).

[0145] In embodiments, the circuitry includes a combination of a circuit and a computer program product having software or firmware instructions stored on one or more computer-readable memories, which work together to cause the device to perform one or more of the protocols, methods, or techniques described herein. In embodiments, the circuitry includes a circuit that requires software, firmware, and the like to operate, such as, for example, a microprocessor or a portion of a microprocessor. In embodiments, the circuitry includes one or more processors or portions thereof, along with attendant software, firmware, hardware, and the like.

[0146] This application may refer to quantities and numbers. Unless otherwise specified, such quantities and numbers should not be considered restrictive, but rather examples of possible quantities or numbers associated with this application. Additionally, in this regard, this application may use the term "plurality" to refer to a quantity or number. In this regard, the term "plurality" means any number greater than one, for example, two, three, four, five, etc. The terms "about", "approximate", "close to", etc. mean plus or minus 5% of the specified value.

Claims

1. A calibration method for calibrating a test instrument (12), the test instrument (12) including at least one port (14, 16), at least one signal analysis module (20) and at least one signal generator module (18), wherein the at least one signal analysis module (20) and the at least one signal generator module (18) are each connected to the at least one port (14, 16), and wherein the calibration method includes the following steps: - Connecting a set of calibration standards successively to the at least one port and performing calibration measurements for each connected calibration standard (34, 36, 38) to obtain a first set of measurement data; - Based on a multi-port error model and the first set of measurement data, determining a plurality of error terms of the multi-port error model, wherein the error terms describe at least the transmissive and reflective characteristics of the at least one port (14, 16), and wherein at least one of the error terms includes a product of two error parameters; - Connecting an additional calibration standard (40) to the at least one port (14, 16), wherein the additional calibration standard (40) is a signal source with known characteristics or a signal sink with known characteristics; - Performing a calibration measurement with the additional calibration standard (40) connected to obtain a second set of measurement data; And - Determining the two error parameters based on the second set of measurement data.

2. The calibration method according to claim 1, wherein The calibration standard is connected to the at least one port (14, 16) at a reference plane (46).

3. The calibration method according to claim 2, wherein A cable is connected to the at least one port (14, 16), and wherein the reference plane (46) is located at an end of the cable away from the at least one port (14, 16).

4. The calibration method according to any one of the preceding claims, wherein, The product of the two error parameters includes a first error parameter and a second error parameter, wherein the first error parameter is directly determined based on the second set of measurement data, and wherein the second error parameter is calculated based on the determined product of the two error parameters and based on the first error parameter.

5. The calibration method according to any one of the preceding claims, wherein, The mismatch of the additional calibration standard (40) is corrected based on the first set of measurement data.

6. The calibration method according to any one of the preceding claims, wherein, The test instrument (12) includes at least one directional coupler (22, 24), and wherein the at least one signal analysis module (20) and the at least one signal generator module (18) are connected to the at least one port (14, 16) through the at least one directional coupler (22, 24).

7. The calibration method according to any one of the preceding claims, wherein, The multi-port error model is an n-term error model, particularly a four-term error model.

8. The calibration method according to any one of the preceding claims, wherein, The multi-port error model is a two-port error model.

9. The calibration method according to any one of the preceding claims, wherein, Calibrating exactly one port of the test instrument (12) at a time.

10. The calibration method according to any one of the preceding claims, wherein, The additional calibration standard (40) is established as a signal generator, a comb generator, an oscilloscope or an analog-to-digital converter.

11. The calibration method according to any one of the preceding claims, wherein, Each calibration standard (34, 36, 38) in the set of calibration standards is provided in a calibration device (28) having a housing (30), wherein the calibration device (28) further includes a switching module (42) and a connection port (32), and wherein the switching module (42) is configured to selectively connect one of the calibration standards (34, 36, 38) to the connection port (32).

12. The calibration method according to claim 11, wherein, The additional calibration standard (40) is provided in the housing (30).

13. The calibration method according to claim 11, wherein, The additional calibration standard (40) is provided separately from the calibration device (28), wherein the calibration device (28) includes an additional connection port (44), and wherein the switching module (42) is configured to selectively connect one of the calibration standards (34, 36, 38) or the additional connection port (44) to the connection port (32).

14. The calibration method according to any one of the preceding claims, wherein, The test instrument (12) is a vector network analyzer, a signal generator, in particular a vector signal generator, or a signal analyzer, in particular a vector signal analyzer.

15. A calibration system (10) comprising a test instrument (12), a set of calibration standards, and an additional calibration standard (40), wherein the calibration system (10) is configured to perform the calibration method according to any one of the preceding claims.

Images