Method for analyzing, in particular scattering parameter analysis, a measurement object, device, in particular network analyzer, for carrying out the method, and use of the device

Abstract

Method for analyzing a measurement object, where n is a number greater than or equal to 1, comprising the following steps: - Generating a generator signal, - Direct forwarding of the generator signal to an input switch (2), - Forwarding the generator signal as a leading wave to a coupling unit (3.1, 3.2, 3.3, 3.4) selected by means of the input switch (2), - Tapping a reference signal (a x = i,j,k,l ) from the leading wave in the coupling unit (3.1, 3.2, 3.3, 3.4), - Forwarding the leading wave to a measuring object, - Return of a wave reflected from the object under test to the selected coupling unit (3.1, 3.2, 3.3, 3.4) and extraction of a corresponding return signal (b x = i,j,k,l ) from the returning wave through the selected coupling unit (3.1, 3.2, 3.3, 3.4) and / or - Transmission of a wave transmitted through the object under test to another coupling unit (3.1, 3.2, 3.3, 3.4) and extraction of a corresponding transmission signal (b x = i,j,k,l ) from the transmitted wave through the other coupling unit (3.1, 3.2, 3.3, 3.4), - Feeding in the tapped signals (a x = i,j,k,l , b x = i,j,k,l ) to a single measuring point (5) via a coupling switch (4), - Separating and demodulating the tapped signals (a x = i,j,k,l , b x = i,i,k,l ) at the measuring point (5) and - Calculation of the behavior of the object being measured at the measuring point (5).

Description

Technical field

[0001] The invention relates to a method for analyzing a measurement object, in particular an n-gate measurement object, according to the preamble of claim 1, as well as a device, in particular a network analyzer, and a use of this device according to the dependent claims. State of the art

[0002] In high-frequency engineering, scattering parameters, also known as S-parameters, are typically used to characterize electrotechnical components. Network analyzers are commonly employed to determine these S-parameters. Such network analyzers are capable of measuring and analyzing the magnitude and phase information of forward, reflected, and transmitted waves from a device connected to the network analyzer.

[0003] Most network analyzers known from the state of the art are equipped with multiple measurement points for acquiring wave quantities, thus enabling the calculation of the S-parameters. For many of these multi-measurement network analyzers, high demands are placed on the components used. Particularly with the so-called 3-channel architecture, high repeatability of the switching characteristics must be ensured. For the calibration of network analyzers based on the 3-channel architecture, the standards used must be fully known. Moving the reference plane to a substrate carrier is difficult to implement in the 3-channel architecture.

[0004] Lower switching requirements come at the cost of a more complex architecture, the so-called 4-channel architecture. The 4-channel architecture also allows for the use of flexible calibration approaches, enabling the definition of a reference plane on a substrate. Furthermore, the 4-channel architecture allows either a reduction in the number of required standards or calibration standards, or a reduction in their requirements, meaning that the properties of the standards only need to be partially known. However, the increased complexity of the 4-channel architecture results in higher costs.

[0005] Document DE 10 2005 058 433 A1 describes a single-point vector network analyzer. Using a single measurement point drastically reduces the required hardware compared to network analyzers with multiple measurement points. However, due to the architecture of the single-point network analyzer, which is based on a 3-channel architecture, only the 12- or 10-term error model can be used for calibration or for calculating the S-parameters. This limits the selection of possible calibration methods and requires a thorough understanding of the calibration standards used. Furthermore, in this network analyzer, a switch that taps off a reference signal from the incoming wave must exhibit high repeatability to ensure acceptable measurement accuracy. Disclosure of the invention

[0006] The object of the invention is to eliminate or at least reduce the disadvantages of the aforementioned prior art. In particular, the object of the invention is to provide an improved method for determining the S-parameters of a measurement object and a simple network analyzer for carrying out the method. Such a network analyzer should be cost-effective, allow the application of flexible calibration methods that enable the use of different calibration standards, and still be capable of delivering precise measurement results.

[0007] The problem is solved by a method for analyzing a measurement object according to claim 1. Independent subject matter of the invention is a device and a use of the device according to the dependent claims.

[0008] The invention offers the advantage over the prior art that only a single measuring point is used. Due to the position of the reference signal tap, systematic errors can be described using the 7-term error model, unlike in the prior art. This results in advantages during calibration due to the usability of flexible algorithms. The use of flexible calibration methods allows the application of different calibration standards, whereby the characteristics of the calibration standards only need to be known to a certain extent. Furthermore, the requirements for the input switch used in a device according to the invention are reduced. Thus, the invention offers a simple and precise investigation of the behavior of electrotechnical objects at a relatively low cost.Another advantage is that a device based on the invention, for example a network analyzer, can be synthetically constructed using standardized functional modules which can also be used independently, resulting in a cost reduction compared to devices that do not have a synthetic structure.

[0009] According to the invention, a method for analyzing a measurement object, in particular an n-port measurement object, where n is a number ≥ 1, is provided. In typical methods, the n-port measurement object is a 2-port measurement object or a 4-port measurement object. In advantageous methods, a generator signal, e.g., a high-frequency signal, is first generated, preferably by a generator. In typical methods, several generator signals are generated by several generators. The generator signal preferably has a frequency of at least 1 Hz, more preferably at least 10 Hz, and particularly preferably at least 100 Hz. In particularly advantageous embodiments, the generator signal has a frequency of at least 1 kHz. The generator signal is first passed to an input switch and then forwarded as a leading wave to a coupling unit selected with the aid of the input switch. In the coupling unit, a reference signal is tapped from the leading wave.The forward wave is transmitted to the object being measured. A wave reflected from the object being measured is fed back to the selected coupling unit. At the selected coupling unit, a corresponding feedback signal from the reflected wave is tapped by the selected coupling unit. In typical methods for analyzing an object being measured, a wave transmitted through the object being measured is transferred to another coupling unit. There, a corresponding transmission signal is tapped from the transmitted wave by the other coupling unit. In the methods according to the invention for analyzing an object being measured or a component, the reference signal, the feedback signal, and the transmission signal are tapped downstream of the input switch, as seen from the generator. The tapped signals, preferably the reference signal and / or the feedback signal and / or the transmission signal, are fed to a single measuring point via a coupling switch.Preferably, the tapped signals are separated and / or demodulated at the measuring point, particularly in an analog-to-digital converter. At the measuring point, preferably in a processing unit or CPU, a calculation or analysis of the behavior of the object under test, in particular a calculation of the scattering parameters of the object under test, is performed.

[0010] In advantageous methods for analyzing a measured object, the signals are extracted and acquired sequentially over time. All signals are acquired and / or processed in a single, identical measurement and / or digitization cycle. In typical methods, the signals are acquired in different digitization cycles, which offers the advantage of lower quality requirements for coupling units or switches. For example, a lower degree of isolation, i.e., crosstalk in the switch, can be tolerated.

[0011] In particularly advantageous methods for analyzing a test object, the generator and a frequency converter are fed from an identical local oscillator. In typical embodiments, the generator and at least one frequency converter are fed from multiple local oscillators or local oscillator systems. These multiple local oscillators or local oscillator systems must reference a common reference or be derived from a common reference to ensure that any frequency offset that may arise between them is minimized. The application of this architecture with multiple local oscillators or local oscillator systems can be advantageous for certain applications, as it also allows the measurement of frequency-converting components.

[0012] In particularly advantageous methods for analyzing or calibrating a measurement object or for determining the S-parameters of the measurement object, the 7-term error model, the 10-term error model, or the 12-term error model is applied to describe the systematic errors that arise during the application of the method. Depending on which error model is applied, different calibration methods can be used, with the 7-term error model having the advantage that the most diverse and flexible methods can be applied. The method according to the invention has the advantage that, for example, the calibration methods TRL, TLR, SOLR, LRRM, LRR, or TAN can be used, and the calibration standards used do not necessarily need to be fully known.In contrast, with the 3-channel architecture, only the SOLT calibration procedure is fully applicable, and the calibration standards used must also be fully known.

[0013] In typical methods for analyzing a measured object, a line standard, a transfer standard, a shaft sump, a sliding load, a short circuit, an open circuit, or a self-calibration standard is used as a calibration standard.

[0014] In advantageous methods for analyzing a measurement object, at least one separation point or a temporal relationship between the reference signal, feedback signal, or transmission signal is determined during calibration. The assignment of the individual signal components at the coupling switch is preferably accomplished automatically during the calibration of the device used to carry out the method according to the invention, which is necessary anyway. A calibration standard must be selected that has a characteristic and known influence on the reflected signal. A match calibration standard, for example, is suitable as such a standard.

[0015] In typical methods, the signal assignment is accomplished automatically using a suitable mathematical procedure. This exploits the fact that the signal proportional to the excitation signal, i.e., the reference signal, does not change and has a constant magnitude during calibration. The remaining task is to detect the discontinuity that arises from the convergence of the different signals. At this point, the recorded signal is separated and assigned to the reference signal, feedback signal, or reflection signal. These temporal relationships remain constant throughout the measurement.In typical methods according to the invention, when the object being measured is changed, an automatic recalibration of the temporal relationship between the reference signal, the feedback signal and the transmission signal takes place, thereby guaranteeing an exact measurement even if the temporal relationships are shifted due to temperature changes.

[0016] A device according to the invention, in particular a network analyzer, comprising a generator, a single measuring point, an input switch, a coupling unit for separating a forward and / or a reflected and / or a transmitted wave, and at least one port or connection for connecting an input or output of a device under test, is characterized in that the coupling unit is suitable for extracting a reference signal from the forward wave and a reflected signal influenced by the device under test from the reflected wave and / or a transmitted signal influenced by the device under test from the transmitted wave, and that this coupling unit is arranged downstream of the input switch from the generator. The coupling unit is preferably suitable for processing frequencies up to 1 THz, preferably up to 500 GHz, and particularly preferably up to 300 GHz.In typical embodiments, the coupling unit is composed of several couplers, with each coupler preferably covering a specific frequency range.

[0017] In preferred embodiments, an output of the generator is directly connected to an input of the input switch. Advantageously, no further component is arranged between the generator and the input switch. Preferably, the output of the generator and the input of the input switch are connected by a single electrical conductor or, preferably, a single conductor combination, e.g., a coaxial conductor, with no branch line existing between the generator and the input switch. This has the advantage that no reference signal is tapped between the generator and the input switch. Instead, a reference signal is tapped only after the input switch, which allows the input switch and its behavior to be taken into account when calculating the S-parameters.In typical embodiments, the generator output is not directly connected to the input of the input switch. Instead, an amplifier, isolator, attenuator, or divider is arranged between the generator and the input switch to enable the parallel operation of several devices, measuring points, or modules according to the invention. In any case, the decoupling or tapping of the reference signal, feedback signal, and transmission signal takes place downstream of the input switch, from the generator's perspective.

[0018] In advantageous embodiments, the input switch is suitable for directing the input signal to the coupling unit or at least one further coupling unit as a leading wave. The input switch is preferably manually or automatically switchable.

[0019] In advantageous embodiments, the measuring point comprises a, preferably a single, frequency conversion and / or a, preferably a single, analog-to-digital converter. In typical embodiments, particularly for the analysis of lower frequencies, frequency conversion is omitted and direct digitization is performed.

[0020] Advantageously, the measuring point includes a computing device, preferably a microprocessor or CPU.

[0021] In advantageous embodiments, the device includes a coupling switch for connecting an output signal from exactly one of the coupling units to the single measuring point. That is, the reference signal, the feedback signal, or the transmission signal is selectively connected to the measuring point. The coupling switch feeds the coupled or tapped signals to the frequency conversion and the analog-to-digital converter (ADC) in a sequential manner. It is particularly preferred if the measuring points of all positions of the coupling switch are acquired in a single measurement cycle, preferably a digitization cycle or ADC cycle, so that the switched signals are in a defined temporal relationship to one another. In typical embodiments, however, the switch and / or the measuring point are also capable of processing the signals in multiple acquisition cycles.

[0022] Preferred embodiments of the device include a local oscillator for powering the generator and the frequency converter. Powering the generator and the frequency converter from one and the same local oscillator has the advantage that signal generation and signal acquisition are precisely synchronized. In typical embodiments, the device includes several local oscillators, all derived from a single reference and thus oscillating synchronously with one another.

[0023] Advantageous embodiments of the device are characterized by their portability. Preferred embodiments have a mass of no more than 10 kg, preferably no more than 7 kg, and more preferably no more than 5 kg. Particularly advantageous embodiments have a mass of no more than 3 kg.

[0024] In a preferred application, the device is integrated as a module, preferably an analysis module for determining the S-parameters of a test object, into another technical device, for example, an oscilloscope, multimeter, or frequency analyzer. The use of the device as a module in semiconductor testers or semiconductor test systems is particularly advantageous. FIGURE DESCRIPTION

[0025] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings; these show in Fig. 1 a schematic view of a network analyzer according to the invention for examining a 2-port measurement object; Fig. 2 a schematic view of a network analyzer according to the invention for examining a 4-port measurement object. Description of preferred embodiments

[0026] Fig. Figure 1 shows a network analyzer according to the invention for determining scattering parameters of a 2-port measurement object. This network analyzer is suitable for carrying out the method according to the invention. Here, a high-frequency signal is first generated by a generator 1 and fed to the input switch 2.

[0027] The high-frequency signal is then routed as a forward wave either towards terminal 9.1 or terminal 9.2. Each terminal 9.1 and 9.2 is connected to a port of the device under test (not shown). The direction of the forward wave, i.e., either towards terminal 9.1 or towards terminal 9.2, is set manually by the user at input switch 2. Automatic adjustment of the signal direction as part of a measurement routine is also possible.

[0028] A reference signal a is generated from the leading shaft at one of the coupling units 3.1 or 3.2, depending on the direction in which terminal 9.1 or 9.2 the leading shaft was routed through the input switch 2. i or a j worn out.

[0029] The portion of the forward wave that is not coupled out or tapped impinges on the object being measured (not shown) at either terminal 9.1 or terminal 9.2. At the object, part of the forward wave is reflected and returned as a reflected wave to the coupling unit 3.1 or 3.2 selected by input switch 2. Another portion of the forward wave enters the object being measured at terminal 9.1 or 9.2 selected by input switch 2, penetrates the object, exits at the other terminal 9.1 or 9.2, and propagates as a transmitted wave towards the coupling unit 3.1 or 3.2 in the direction to which the forward wave was not transmitted by input switch 2.

[0030] In the two coupling units 3.1 and 3.2, a feedback signal and a transmission signal are generated from the reflected and transmitted waves, respectively. i or b j, picked up or decoupled.

[0031] The tapped or coupled quantities “reference signal”, “feedback signal” and “transmission signal” meet a coupling switch 4, through which the signals are fed to the measuring point 5 in a sequential manner.

[0032] At measuring point 5, the signals first undergo a frequency conversion 6 and are then digitized in an analog-to-digital converter 7. The measurement points of all switch positions of the coupling switch 4 are recorded in a single digitization cycle, ensuring that the switched signals are in a defined temporal relationship to one another. Theoretically, it is also possible to divide the signal acquisition into several acquisition cycles, but this increases the synchronization effort.

[0033] Generator 1 and frequency converter 6 are connected to a single local oscillator (not shown). Using a single local oscillator ensures phase coherence. However, generator 1 and frequency converter 6 could equally well be driven by two separate local oscillators derived from a common reference.

[0034] In a computing unit 8 connected downstream of the analog-to-digital converter 7, the signals are separated and IQ-demodulated. The S-parameters are then calculated using the generally known method.

[0035] Fig. 2 shows one of the network analyzers from Fig. 1 comparable network analyzer, however not for calculating the S-parameters of a 2-port measurement object, but for calculating the S-parameters of a 4-port measurement object. The structure of this network analyzer is similar to that of the network analyzer in Fig. 2 is very similar, however it differs from the network analyzer in the number of connections 9.1 to 9.4 (4 instead of 2 connections) and in the number of coupling units 3.1 to 3.4 (4 instead of 2 coupling units). Fig. 2. Also in the Fig. However, the network analyzer shown in Figure 3 only requires one measuring point 5 with a frequency converter 6, an analog-to-digital converter 7 and a computing unit 8.

[0036] The invention is not limited to the described embodiments. Rather, the scope of protection is determined by the patent claims. Reference symbol list 1 Generator 2 input switches 3 coupling unit 4 coupling switches 5 measuring point 6 Frequency conversion 7 Analog-to-Digital Converters 8 Computing equipment 9 connection a x = i,j,k,l leading wave b x= i,j,k,l reflected or transmitted wave

Claims

[1] Method for analyzing a measurement object, where n is a number greater than or equal to 1, comprising the steps: - Generating a generator signal, - Direct forwarding of the generator signal to an input switch (2), - Forwarding the generator signal as a leading wave to a coupling unit (3.1, 3.2, 3.3, 3.4) selected by means of the input switch (2), - Tapping a reference signal (a x = i,j,k,l ) from the leading wave in the coupling unit (3.1, 3.2, 3.3, 3.4), - Forwarding the leading wave to a measuring object, - Return of a wave reflected from the object under test to the selected coupling unit (3.1, 3.2, 3.3, 3.4) and extraction of a corresponding return signal (b x = i,j,k,l ) from the returning wave through the selected coupling unit (3.1, 3.2, 3.3, 3.4) and / or - Transmission of a wave transmitted through the object under test to another coupling unit (3.1, 3.2, 3.3, 3.4) and extraction of a corresponding transmission signal (b x = i,j,k,l ) from the transmitted wave through the other coupling unit (3.1, 3.2, 3.3, 3.4), - Feeding in the tapped signals (a x = i,j,k,l , b x = i,j,k,l ) to a single measuring point (5) via a coupling switch (4), - Separating and demodulating the tapped signals (a x = i,j,k,l , b x = i,i,k,l ) at the measuring point (5) and - Calculation of the behavior of the object being measured at the measuring point (5). [2] Method according to claim 1, characterized by , that the signals (a x = i,j,k,l , b x = i,i,k,l ) are extracted and recorded sequentially over time, with all signals (a x = i,j,k,l , b x = i,j,k,l) are recorded in one measurement cycle. [3] Method according to one of claims 1 or 2, characterized by , that a generator (1) and a frequency converter (6) are fed from an identical local oscillator or from several local oscillators derived from a common reference. [4] Method according to any one of claims 1 to 3, characterized by , that the 7-term error model is applied for calibration or for determining the S-parameters of the object being measured. [5] Method according to any one of claims 1 to 4, characterized by , that reference signal (a x = i,j,k,l ), return signal (b x = i,j,k,l ) and transmission signal (b x = i,i,k,l ) after the input switch (2) in the coupling unit (3.1, 3.2, 3.3, 3.4). [6] Method according to any one of claims 1 to 5, characterized by that at least one discontinuity or temporal relationship between reference signal (ax = i,j,k,l ), return signal (b x = i,j,k,l ) or transmission signal (b x = i,j,k,l ) is determined during calibration. [7] Device for carrying out the method according to any one of claims 1 to 6, comprising at least - a generator (1), - a single measuring point (5), - an input switch (2), - a coupling unit (3.1, 3.2, 3.3, 3.4) for separating a forward and a reverse wave and - at least one connection (9.1, 9.2, 9.3, 9.4) for connecting an input or output of a device under test, characterized by , that the coupling unit (3.1, 3.2, 3.3, 3.4) which is suitable to provide a reference signal (a x = i,j,k,l ) to be coupled out of the leading shaft or tapped from the leading shaft, is arranged after the input switch (2) as seen from the generator (1). [8] Device according to claim 7, characterized by , that the coupling unit (3.1, 3.2, 3.3, 3.4) is suitable to provide a feedback signal (b x = i,j,k,l ) from the returning wave and / or a transmission signal (b x = i,j,k,l ) to extract from the transmitted wave or to tap from the reflected or transmitted wave. [9] Device according to one of claims 7 or 8, characterized by , that an output of the generator (1) is directly connected to an input of the input switch (2). [10] Device according to any one of claims 7 to 9, characterized by , that the input switch (2) is suitable to direct the input signal to the coupling unit (3.1, 3.2, 3.3, 3.4) or to at least one further coupling unit (3.1, 3.2, 3.3, 3.4) as a leading wave. [11] Device according to any one of claims 7 to 10, characterized by , that the measuring point (5) includes a frequency conversion (6). [12] Device according to any one of claims 7 to 11, characterized by, that the measuring point (5) includes an analog-to-digital converter (7). [13] Device according to any one of claims 7 to 12, characterized by that the measuring point (5) includes a computing device (8). [14] Device according to claim 10, characterized by a coupling switch (4) for connecting an output of exactly one of the coupling units (3.1, 3.2, 3.3, 3.4) to the single measuring point (5). [15] Device according to any one of claims 7 to 14, characterized by a local oscillator to power the generator (1) and the frequency conversion (6). [16] Device according to any one of claims 7 to 15, characterized by that the device is portable. [17] Use of the device according to any one of claims 7 to 16 in other devices or instruments as an analysis module or for testing semiconductor components. [18] Use of a plurality of devices according to any one of claims 7 to 16 as modules in a measuring instrument.

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