MEASUREMENT SYSTEM AND MEASUREMENT METHOD

Abstract

A measurement system for characterizing a device under test is described. The measurement system includes a signal source, an analysis module, and a directional element that is connected to each of the device under test, the signal source, and the analysis module. The signal source is configured to generate a digital instruction signal or an analog stimulus signal for the device under test. In the case of generating the analog stimulus signal, the directional element is configured to forward the analog stimulus signal from the signal source to the device under test, wherein the device under test includes circuitry configured to generate a digital output signal based on the analog stimulus signal received. In the case of generating the digital instruction signal by the signal source, the device under test includes circuitry configured to generate an analog output signal based on the digital instruction signal received, wherein the directional element is configured to forward the analog output signal generated to the analysis module. The analysis module includes circuitry configured to determine at least one characteristic parameter of the device under test based on the analog output signal of the device under test or the digital output signal of the device under test. Moreover, a measurement method for characterizing a device under test is described.

Claims

1. A measurement system for characterizing a device under test, comprising: a signal source, an analysis module, and a directional element that is connected to each of the device under test, the signal source, and the analysis module, wherein the device under test is established as an RF-to-digital device comprising an analog input, or wherein the device under test is established as a digital-to-RF device comprising a digital input; wherein the signal source is configured to generate a digital instruction signal or an analog stimulus signal for the device under test; wherein, in the case of generating the analog stimulus signal by the signal source, the directional element is configured to forward the analog stimulus signal from the signal source to the device under test, wherein the device under test is configured to generate a digital output signal based on the analog stimulus signal received, wherein the digital output signal is forwarded to the analysis module; wherein, in the case of generating the digital instruction signal by the signal source, the device under test is configured to generate an analog output signal based on the digital instruction signal received, wherein the directional element is configured to forward the analog output signal generated to the analysis module; and wherein the analysis module includes circuitry configured to determine at least one characteristic parameter of the device under test based on the analog output signal of the device under test or the digital output signal of the device under test.

2. The measurement system of claim 1, wherein the directional element is configured to forward a reflected signal to the analysis module, wherein the reflected signal is reflected at the analog input of the device under test.

3. The measurement system of claim 2, wherein the analysis module includes circuitry configured to determine the at least one characteristic parameter based on the reflected signal.

4. The measurement system according to claim 1, wherein the at least one characteristic parameter comprises at least one of an error vector magnitude, an amplitude response of the device under test, a phase response of the device under test, a frequency response of the device under test, a non-linearity of the device under test, an S-parameter of the device under test, or a group delay of the device under test.

5. The measurement system according to claim 1, wherein the device under test has at least one of a receiving mode and a transmitting mode.

6. The measurement system according to claim 5, wherein the signal source is configured to generate an analog test signal if the device under test is in the transmitting mode, wherein the directional element is configured to forward the analog test signal to the analog input of the device under test, and wherein the directional element is configured to forward a reflected portion of the analog test signal reflected at the analog input to the analysis module.

7. The measurement system according to claim 6, wherein the analog test signal is separable from the analog output signal of the device under test.

8. The measurement system of claim 7, wherein the analog test signal is orthogonal to the analog output signal, thereby ensuring the separability of the analog test signal and the analog output signal.

9. The measurement system according to claim 1, wherein the analysis module is established as a vector signal analyzer.

10. The measurement system according to claim 1, wherein the signal source is established as a vector signal generator.

11. The measurement system according to claim 1, wherein the directional element is established as a directional coupler.

12. The measurement system according to claim 1, wherein the analog output signal or the analog stimulus signal comprises a marker.

13. The measurement system according to claim 1, wherein at least one of the signal source or the device under test is configured to generate a reference signal and to forward the reference signal to the analysis module.

14. The measurement system according to claim 1, further comprising a control module including circuitry configured to control at least one of the signal source, the analysis module, and the device under test.

15. The measurement system according to claim 1, wherein the analog stimulus signal is established as a wideband modulated signal.

16. The measurement system according to claim 1, wherein the digital instruction signal is established as a digital IQ signal.

17. A measurement method for characterizing a device under test, wherein the device under test is established as an RF-to-digital device comprising an analog input, or wherein the device under test is established as a digital-to-RF device comprising a digital input, comprising: generating a digital instruction signal or an analog stimulus signal for the device under test by a signal source; in the case of generating the analog stimulus signal by the signal source, forwarding the analog stimulus signal to the device under test by a directional element, generating a digital output signal based on the analog stimulus signal by the device under test, and forwarding the digital output signal to an analysis module; in the case of generating the digital instruction signal by the signal source, forwarding the digital instruction signal to the device under test, generating an analog output signal based on the digital instruction signal by the device under test, and forwarding the analog output signal to the analysis module via the directional element; and determining, by the analysis module, at least one characteristic parameter of the device under test based on the analog output signal of the device under test or the digital output signal of the device under test.

Description

DESCRIPTION OF THE DRAWINGS

[0049] The foregoing aspects and many of the attendant advantages of the claimed subject matter will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0050] FIG. 1 schematically shows a block diagram of a measurement system according to an embodiment of the present disclosure; and

[0051] FIG. 2 shows a flow chart of a measurement method according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0052] The detailed description set forth above in connection with the appended drawings, where like numerals reference like elements, are intended as a description of various embodiments of the present disclosure and are not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Similarly, any steps described herein may be interchangeable with other steps, or combinations of steps, in order to achieve the same or substantially similar result. Moreover, some of the method steps can be carried serially or in parallel, or in any order unless specifically expressed or understood in the context of other method steps.

[0053] In the foregoing description, specific details are set forth to provide a thorough understanding of exemplary embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that the embodiments disclosed herein may be practiced without embodying all of the specific details. In some instances, well-known process steps have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein.

[0054] Throughout this specification, terms of art may be used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise.

[0055] FIG. 1 schematically shows a measurement system 10 comprising a device under test 12, a signal source 14, an analysis module 16, and a directional element 18.

[0056] In some embodiments, the term “module” refers to or includes, inter alia, a combination of hardware (e.g. a processor such as an integrated circuit, digital circuits or other circuitry) and software (e.g. machine- or processor-executable instructions, commands, or code such as firmware, programming, or object code). Furthermore, a combination of hardware and software may include hardware only (i.e. a hardware element with no software elements), software hosted at hardware (e.g. software that is stored at a memory and executed or interpreted at a processor), or hardware with the software hosted thereon. In some embodiments, the hardware may, inter alia, comprise a CPU, a GPU, an FPGA, an ASIC, or other types of electronic circuitry.

[0057] The device under test 12 is established as an RF-to-digital device comprising at least one analog input 20 and at least one digital output 22, and/or as a digital-to-RF device comprising at least one digital input 24 and at least one analog output 26. Accordingly, the device under test 12 may be configured to receive an analog signal via the analog input 20, and to generate a digital output signal x.sub.out,d based on the received analog signal. Alternatively or additionally, the device under test 12 may be configured to receive a digital input signal via the digital input 24, and to generate an analog output signal x.sub.out,a based on the received digital signal.

[0058] The digital input 24 and/or the digital output 22 may each be configured as a digital streaming interface that is configured to receive a digital signal or transmit a digital signal, respectively. Alternatively or additionally, the digital input 24 and/or the digital output 22 may each be established as another type of digital interface for data transfer, e.g. as a USB interface, as a LAN interface, etc.

[0059] In general, the signal source 14 is configured to generate an analog stimulus signal x.sub.st for the device under test 12 and/or a digital instruction signal x.sub.inst for the device under test 12. For example, the signal source 14 may be established as a vector signal generator.

[0060] In embodiments of the disclosure, the analysis module 16 includes, inter alia, circuitry configured to analyze the analog output signal x.sub.out,a of the device under test 12 and/or the digital output signal x.sub.out,d of the device under test 12. For example, the analysis module 16 is established as a vector signal analyzer. Alternatively, the analysis module 16 may be established as an oscilloscope or as a computer with a suitable measurement application.

[0061] In some embodiments, the analysis module 16 may comprise a control module 28 comprising circuitry configured to control the signal source 14 and/or the device under test 12 via a corresponding control signal x.sub.cont that is generated by the control module 28. The control signal x.sub.cont may be forwarded to the signal source 14 and/or to the device under test 12 via LAN or via another suitable type of connection. In some embodiments, the control module 28 may also be configured to control the analysis module 16.

[0062] Alternatively, the control module 28 may be established separately from the analysis module 16, and may be configured to also control the analysis module 16. For example, the control module 28 is established as a computer with a suitable software application.

[0063] The directional element 18 is connected to each of the signal source 14, the analysis module 16, and at least to the analog input 20 of the device under test 12. In some embodiments, the directional element is also connected to the analog output 26 of the device under test 12.

[0064] In general, the directional element 18 is configured to forward any analog signal coming from the signal source 14 to the device under test 12, more precisely to the analog input 20 of the device under test 12. Moreover, the directional element 18 is configured to forward any analog signal coming from the device under test 12, for example coming from the analog output 26 of the device under test 12 or from the analog input 20 of the device under test 12 to the analysis module 16. In some embodiments, the directional element 18 may be established as a directional coupler.

[0065] In general, the measurement system 10 is configured to characterize the device under test 12 with respect to transmission properties and reflection properties, and with respect to a quality of the output signal (x.sub.out,a and/or x.sub.out,d) generated by the device under test 12. For example, the measurement system 10 is configured to perform a representative measurement method which is described in the following with reference to the embodiment of FIG. 2.

[0066] An analog stimulus signal x.sub.st and/or a digital instruction signal x.sub.inst is generated by the signal source 14 (step S1). If the digital instruction signal x.sub.inst is generated, it is forwarded directly to the digital input 24 of the device under test 12.

[0067] The digital instruction signal x.sub.inst may be established as an IQ data signal comprising information on the analog output signal x.sub.out,a that is to be generated with predefined properties by the device under test 12. In some embodiments, the digital instruction signal x.sub.inst may comprise information on a modulation and a frequency content of the analog output signal x.sub.out,a that is to be generated. In principle, the digital instruction signal x.sub.inst may also be forwarded to the device under test 12 via the directional element 18.

[0068] If the analog stimulus signal x.sub.st is generated, it is forwarded to the device under test 12 or rather to the analog input 20 of the device under test 12 via the directional element 18. The analog stimulus x.sub.st signal may be established as a wideband modulated signal having a predefined modulation and a predefined frequency content.

[0069] In either case, the device under test 12 generates an output signal based on the signal received from the signal source 14 (step S2).

[0070] If the digital instruction signal is received, then the device under test 12 generates the analog output signal x.sub.out,a and transmits the analog output signal x.sub.out,a via the analog output 26. The analog output signal x.sub.out,a is then forwarded to the analysis module 16 via the directional element 18.

[0071] If the analog stimulus signal x.sub.st is received, then the device under test 12 may generate a digital output signal x.sub.out,a that is transmitted via the digital output 22 and may be forwarded directly to the analysis module 16. In other words, the device under test 12 may be in a transmitting mode.

[0072] It is noted that the digital output signal could, in principle, be forwarded to the analysis module 16 via the directional element 18.

[0073] Alternatively, the device under test 12 may be in a receiving mode. In the receiving mode, the device under test 12 receives the analog stimulus signal x.sub.st and processes, via one or more circuits, the analog stimulus signal x.sub.st internally. Accordingly, the device under test 12 may generate a digital set of processed data based on the analog stimulus signal x.sub.st.

[0074] The digital set of processed data may then be forwarded to the analysis module 16 or read out by the analysis module 16 via the digital output 22. In other words, in this case the digital output signal x.sub.out,a of the device under test 12 may be the digital set of processed data described above.

[0075] Alternatively or additionally, the device under test 12 may receive and process a digital signal via the digital input in the receiving mode. In some embodiments, the device under test 12 receives and processes the digital instruction signal. For example, the device under test 12 may store the received digital signal in the receiving mode.

[0076] At least one characteristic parameter of the device under test 12 is determined based on the analog output signal x.sub.out,a and/or based on the digital output signal x.sub.out,a (step S3).

[0077] The at least one characteristic parameter comprises at least one of, for example several or all of an error vector magnitude, an amplitude response of the device under test 12, a phase response of the device under test 12, a frequency response of the device under test 12, a non-linearity of the device under test 12, an S-parameter of the device under test 12, and/or a group delay of the device under test 12.

[0078] In order to determine some of these quantities, a reference signal may be necessary. For example, in order to determine the amplitude response, the phase response, the frequency response, the non-linearity, or the S-parameters of the device under test 12, an output signal of the device under test 12 needs to be compared with the corresponding input signal. Accordingly, the signal source 14 and/or the device under test 12 may be configured to forward a corresponding reference signal x.sub.ref to the analysis module 16.

[0079] Alternatively or additionally, the analog stimulus signal x.sub.st and/or the analog output signal x.sub.out,a may comprise a marker. The marker may indicate the start of the transmission of the analog output signal x.sub.out,a or the start of the transmission of the analog stimulus signal x.sub.st.

[0080] Alternatively or additionally, the marker may be established as a predefined waveform in the analog output signal x.sub.out,a or in the analog stimulus signal x.sub.st. For example, the predefined waveform may serve as a trigger event for a trigger of the analysis module 16. Thus, the analysis module 16 may use the marker in order to synchronize itself with the signal source 14 and/or with the device under test 12. Alternatively or additionally, the analysis module 16 may use the marker to synchronize the digital output signal x.sub.out,a with the reference signal x.sub.ref.

[0081] If the signal source 14 generates the analog stimulus signal x.sub.st, reflections may occur at the analog input of the device under test 12. The corresponding reflected signal x.sub.refl may be forwarded to the analysis module 16 via the directional element 18 and may be analyzed in order to determine the at least one characteristic parameter (step S4).

[0082] In some embodiments, an S11-parameter of the device under test 12 or rather of the analog input 20 can be determined based on the reflected portion of the analog stimulus signal x.sub.st. In some embodiments, the S11-parameter may be determined via a so-called hot S-parameter measurement.

[0083] When the device under test 12 is generating the analog output signal x.sub.out,a based on the digital instruction signal x.sub.inst, the signal source 14 may generate an analog test signal x.sub.test that is forwarded to the analog input 20 via the directional element 18. A portion of the test signal x.sub.test is reflected at the analog input 20, wherein the reflected portion is forwarded to the signal source 14.

[0084] Therein, the test signal x.sub.test is generated with predefined properties, such that the test signal x.sub.test is separable from the analog output signal x.sub.out,a of the device under test 12. In other words, the test signal x.sub.test is generated such that the analysis module 16 can clearly distinguish between the test signal x.sub.test and the analog output signal x.sub.out,a. For example, the analog test signal x.sub.test has a frequency or frequency range that is distinguishably different from the analog output signal of the device under test 12.

[0085] In some embodiments, the analog test signal x.sub.test is orthogonal to the analog output signal x.sub.out,a. For example, one or several carriers of the analog test signal x.sub.test having certain carrier frequencies may be orthogonal to the corresponding carrier(s) of the analog output signal x.sub.out,a

[0086] Thus, the analysis module 16 can clearly distinguish between the analog test signal x.sub.test and the analog output signal x.sub.out,a, and can determine the S11-parameter and the other characteristic parameters of the device under test 12 simultaneously, even if the analog test signal x.sub.test and the analog output signal x.sub.out,a are superposed.

[0087] Summarizing, the measurement system 10 and the measurement method described above provide the possibility to test the performance of the device under test 12 by determining the at least one characteristic parameter, irrespective of whether the device under test 12 is established as an analog-to-digital (or rather RF-to-digital) device or as a digital-to-analog (or rather digital-to-RF) device.

[0088] Certain embodiments disclosed herein, for example the respective module(s), utilize circuitry (e.g., one or more circuits) in order to implement standards, protocols, methodologies or technologies 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. Circuitry of any type can be used. It will be appreciated that the term “information” can be use synonymously with the term “signals” in this paragraph. It will be further appreciated that the terms “circuitry,” “circuit,” “one or more circuits,” etc., can be used synonymously herein.

[0089] In an embodiment, circuitry includes, among other things, 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 combinations thereof, and can include discrete digital or analog circuit elements or electronics, or combinations thereof. In an embodiment, circuitry includes hardware circuit implementations (e.g., implementations in analog circuitry, implementations in digital circuitry, and the like, and combinations thereof).

[0090] In an embodiment, circuitry includes combinations of circuits and computer program products having software or firmware instructions stored on one or more computer readable memories that work together to cause a device to perform one or more protocols, methodologies or technologies described herein. In an embodiment, circuitry includes circuits, such as, for example, microprocessors or portions of microprocessor, that require software, firmware, and the like for operation. In an embodiment, circuitry includes one or more processors or portions thereof and accompanying software, firmware, hardware, and the like.

[0091] The present application may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive, but exemplary of the possible quantities or numbers associated with the present application. Also in this regard, the present application may use the term “plurality” to reference a quantity or number. In this regard, the term “plurality” is meant to be any number that is more than one, for example, two, three, four, five, etc. The terms “about,” “approximately,” “near,” etc., mean plus or minus 5% of the stated value. For the purposes of the present disclosure, the phrase “at least one of A and B” is equivalent to “A and/or B” or vice versa, namely “A” alone, “B” alone or “A and B.”. Similarly, the phrase “at least one of A, B, and C,” for example, means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible permutations when greater than three elements are listed.

[0092] The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure which are intended to be protected are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure, as claimed.