EP2300835A1

EP2300835A1 - Measurement probe

Info

Publication number: EP2300835A1
Application number: EP09776813A
Authority: EP
Inventors: Thomas Zelder; Bernd Geck
Original assignee: Rosenberger Hochfrequenztechnik GmbH and Co KG
Current assignee: Rosenberger Hochfrequenztechnik GmbH and Co KG
Priority date: 2008-07-15
Filing date: 2009-06-23
Publication date: 2011-03-30
Also published as: CN102099693B; JP2011528107A; JP5826628B2; DE202008009469U1; HK1157017A1; CA2725636C; CA2725636A1; CN102099693A; US20110163773A1; WO2010006683A1; US8760184B2

Abstract

The invention relates to a measurement probe, particularly for a non-contacting vector network analysis system, having a housing (10) and at least one coupling structure (12) disposed on the housing (10) and designed for coupling an HF signal from a signal line (16), wherein the arrangement is made such that at least one additional signal probe (14) is disposed on the housing (10) for coupling an electrical signal into the signal line (16).

Description

probe

The present invention relates to a measuring probe, in particular for a contactless vector network analysis system, comprising a housing and at least one coupling structure arranged on the housing, which is designed for coupling out an HF signal from a signal line, according to the preamble of claim 1.

The use of non-contact loop probes to detect spurious emissions is particularly useful in the field of electromagnetic compatibility (EMC), for example, in H. Whiteside, RWP King, "The loop antenna as a probe," IEEE Transaction on Antenna and Propagation, Vol. No. 3, pp. 291-297, May 1964; M. Kanda, "An electromagnetic near-field sensor for simultaneous electric and magnetic-field measurements," IEEE Transaction on Electromagnetic Compatibility, Vol. 26, No. 3, pp. 102-110, August 1984, or MEG Upton, AC Marvin, " Improvements to an electromagnetic near-field sensor for simultaneous electric and magnetic field measurements, "IEEE Transaction on Electromagnetic Compatibility, Vol. 35, No. 1, pp. 96-98, February 1993.

Furthermore, it is for example from KW Wagner, "Induction effect of traveling waves in neighboring lines," Elektrotechnische Zeitschrift, Volume 35, pp 639-643; 677-680; 705-708, 1914; PP Lombardini, RF Schwartz, PJ Kelly, "Criteria for the design of loop-type directional couplers for the L band," IEEE Transaction on Microwave Theory and Techniques, Vol. 4, No. 4, pp. 234-239, October 1956; B. Mower, "An L-band loop-type coupler," IEEE Transactions on Microwave Theory and Techniques, Vol. 9, No. 4, pp. 362-363, July 1961; F. De Groote, J. Verspecht, C. Tsironis Barataud, D., and J.P. Teyssier, "An Improved Coupling Method for Time Domain Load-Pull Measurements" European Microwave Conference, Vol. 1, p. 4ff, October 2005, or K. Yhland, J. Stenarson, "Noncontacting measurement of power in microstrip circuits, "in 65th ARFTG, pp 201-205, June 2006, known to use loop probes in the realization of directional couplers A directional coupler is a four-port, which usually consists of two interconnected lines has the task of separating the waves flowing back and forth on a pipe.

Instead of loop probes, purely inductive or capacitive probes are used in EMC technology and for the characterization of electrical components, as for example from T. Zelder, H. EuI, "Contactless network analysis with improved dynamic range using diversity calibration," Proceedings of the 36th European Microwave Conference, Manchester, UK, p. 478-481, September 2006; T. Zelder, H. Rabe, H. EuI, "Contactless electromagnetic measuring system using conventional calibration algorithms to determine scattering parameters," Advances in Radio Science - Kleinheubacher reports 2006, volume 5, 2007; T. Zelder, I. Rolfes, H. EuI, "Contactless vector network analysis using diversity calibration with capacitive and inductive coupled probes," Advances in Radio Science - Kleinheubacher Reports 2006, Vol. 5, 2007 or J. Stenarson, K. Yhland, Wingqvist, "An in-circuit noncontacting measurement method for S-parameters and power in planar circuits," IEEE Transactions on Microwave Theory and Techniques, Vol. 49, No. 12, pp. 2567-2572, December 2001.

A possible coupling structure for separating the traveling and returning waves is the loop-directional coupler, which PP Lombardini, RF Schwartz, PJ Kelly, "Criteria for the design of loop-type Directional couplers for the L band" IEEE Transaction on Microwave Theory and Techniques, Vol 4, No. 4, pp. 234-239, October 1956 and B. Mower, "An L-band loop-type coupler" IEEE Transactions on Microwave Theory and Techniques, Vol. 9, No. 4, pp. 362-363, July 1961 describe. One Loop-wise coupler consists of a conductor loop which is positioned over or in a waveguide. In this case, any waveguide such as hollow lines, planar strip lines or coaxial cables can be used. The application of a Schleifenrichtkopplers is varied. For example, F. De Groote et al. in 2005 (loc. cit.) and Yhland et al. 2006 (loc. Cit.) A loop-wise coupler as a component in a contactless measuring system.

The determination of scattering parameters of embedded within a complex circuit electrical components is possible by means of contactless vector network analysis. This is described, for example, in T. Zelder, B. Geck, M. Wollitzer, I. Rolfes, and H. EuI, "Contactless network analysis system for the calibrated measurement of the scattering parameters of planar two-port devices" Proceedings of the 37th European Microwave Conference, Munich, Germany, pp. 246-249, October 2007. Compared to the conventional contact-based network analysis method, the internal directional couplers of a network analyzer are replaced by contactless near-field probes connected directly to the vectorial measurement sites of the analyzer.

To determine the scattering parameters of a test object (DUT) with a contactless, mostly vectorial measuring system are inductive and / or capacitive

Coupling structures used. The probes are in electromagnetic

Near field positioned above the signal lines of the measurement object. By means of this

Coupling structures are either the current and / or the voltage of a

Signal line, which is connected directly to the test object determined. Alternatively, the waves traveling back and forth on the signal line are also measured, with directional couplers, in particular loop-wise couplers, being used as coupling structures for separating the two waves. To measure the scattering parameters, conventional calibration methods such as TRL (G.F.

Engen and CA Hoer, "Thru-reflect-line: An improved technique for calibrating the dual six-port automatic network analyzer," IEEE Transaction on Microwave Theory and Techniques, Vol. 12, pp. 987-993, December 1979), as in the contact network analysis used. In contactless vector network analysis, at least one measuring probe, for example a conductor loop or two capacitive probes, is required for each test port of an unknown test object (DUT). For example, contactless conductor loops made of coaxial semi-rigid leads are used (see F. De Groote, J. Verspecht, C. Tsironis, D. Barataud and J.-P. Teyssier, An improved coupling method for Time domain load-pull measurements ", European Microwave Conference, Volume 1, pp. 4 et seq., October 2005 and K. Yhland, J. Stenarson," Noncontacting Measurement of Power in Microstrip Circuits ", in 65th ARFTG, p. 205, June, 2006. Alternatively, only capacitive probes are used in contactless measurement systems (see T. Zelder, H. EuI, "Contactless Network Analysis with Improved Dynamic Range Using Diversity Calibration", Proceedings of the 36th European Microwave Conference, Manchester, UK, pp. 478-481, September 2006 and T. Zelder, H. Rabe, H. EuI, "Contactless electromagnetic measuring system using conventional calibration algorithms to determine scattering parameters", Advances in Radio Science - Kleinheubacher Reports 2006, Vol. 2007. Tue Messrs. Zelder, I. Rolfes, H. EuI, "Contactless vector network analysis using diversity calibration with capacitive and inductive coupled probes", Advances in Radio Science - Kleinheubacher Reports 2006, Vol. 5, 2007 and J. Stenarson, K Yhland, C. Wingqvist, "An in-circuit noncontacting measurement method for S-parameters and power in planar circuits", IEEE Transactions on Microwave Theory and Techniques, Vol. 49, No. 12, pp. 2567-2572, December, 2001 , were realized with a combination of capacitive and inductive probes. The peculiarity of the probes in T. Zelder et al. (supra) is that they are made together with the signal line on the same substrate.

Although contactless vector network analysis has the potential to characterize components without contact, no contactless scatter parameter measurement has been performed by RF and microwave components embedded within a circuit. So far, the positions of the contactless probes have not been changed during and after the calibration, which is necessary, however, when measuring within a circuit. Under using a pseudo-contactless measurement were described in T. Zelder, B. Geck, M. Wollitzer, I. Rolfes, and H. EuI, "Contactless network analysis system for the calibrated measurement of the scattering parameters of planar two-port devices ", Proceedings of the 37th European Microwave Conference, Munich, Germany, pp. 246-249, October 2007. In this case, a pseudo-contactless measurement means that printed coupling structures are used instead of completely contactless probes.

For non-contact determination of complex-value scattering parameters of a two-port, two contactless loop probes are connected to two measuring points each of a vectorial network analyzer. The probes are positioned bilaterally in the near field of the DUT's leads to characterize a DUT (Devide Under Test) embedded between multiple devices. To determine the

Scattering parameters measure the return waves of the DUT in two different states. To generate two different states, a network analyzer has a toggle switch so that the signal can be put into the circuit once from the left or right. Be for both

Switch positions measured back and forth waves, then the full two-port scattering parameters of an embedded DUTs can be determined. However, in non-contact determination, the

Scattering parameters Cases in which a determination of the complete scattering parameters is not possible. Two cases are explained below.

Case 1: For example, if the last two port (34 in FIG. 3 between 44 and 46) in the circuit in which the DUT is embedded is an amplifier only in the forward direction

(Switch position I, see Fig. 3) can be operated (in the other direction he has a very high input resistance) and are the two outputs of

Switch 54, as usual in the contactless vector network analysis, instead of interconnected as shown in Fig. 3 with the planar line 16 at the positions 36 and 46, then results only for the switch position I evaluable results.

For the switch position II almost the entire power is reversed operated amplifier reflected back to the generator and the measurement signal at the measuring points of the contactless loop probes disappears in the noise.

Case 2: If the attenuation of the two-ports in the circuit to the left and right of the DUT is too high, then the dynamic range for an accurate measurement is too low.

The invention has for its object to provide a probe of o.g. To improve the type of measurement accuracy and application spectrum.

This object is achieved by a probe of o.g. Art solved with the features characterized in claim 1. Advantageous embodiments of the invention are described in the further claims.

For a probe of the o.g. It is inventively provided that on the housing in addition at least one signal probe for coupling an electrical signal is arranged in the signal line.

This has the advantage that the signal passed through a DUT for carrying out measurements need not be routed to the DUT across all the components of the circuit in which the DUT is embedded, but instead the signal directly before or after the DUT with a measuring tip (sample) is fed. As a result, DUTs can be completely measured with regard to their scattering parameters independently of the other components present in the circuit.

The signal probe is expediently designed as a contactless conductor loop or as a measuring tip electrically and mechanically contacting the signal line, wherein the measuring tip is arranged and configured such that the coupling structure is located at least in the near field of the signal line or electrically and mechanically contacts the signal line when the measuring tip Signal line electrically and mechanically contacted. Conveniently, the contactless signal probe is designed as a purely inductive, purely capacitive or combined inductive and capacitive probe.

In a preferred embodiment, the coupling structure is designed as a contactless conductor loop or as a measuring tip electrically and mechanically contacting the signal line.

Conveniently, the contactless coupling structure is designed as a purely inductive, purely capacitive or combined inductive and capacitive probe.

Conveniently, a ground contact of the coupling structure and the signal probe are electrically connected together.

The fact that the coupling structure is impedance-controlled, a high directivity and a high input impedance is achieved and less sheath waves are generated, whereby the probe also analytically better describable and the cutoff frequency is higher than in non-impedance-controlled probes.

To improve the signal quality, an electrical signal amplifier is arranged in an input path of the signal probe and / or in an output path of the coupling structure.

For setting an operating point of the amplifier, the signal probe and / or the coupling structure is / is subjected to a DC voltage.

In a preferred embodiment, the housing is made of a metallic material, an absorber material and / or a plastic.

Conveniently, the housing is sheathed with an absorber material. For distance-controlled arrangement of the measuring probe near or in electrical and mechanical contact with the signal conductor, a device for determining a distance of the coupling structure from the signal conductor is additionally provided.

By way of example, the device for determining the distance comprises an optical, electrical, mechanical and / or electromechanical distance sensor.

For controlled, three-dimensional arrangement of the probe near or in mechanical and electrical contact with the signal conductor, a device for determining a position of the probe in space is additionally provided.

For example, the device for determining a position of the measuring probe in space is an image sensor.

In a preferred embodiment, the measuring probe additionally has at least one positioning device for positioning it in space, so that the measuring probe can be displaced in at least one spatial direction. The positioning device has, for example, at least one positioning motor, in particular a stepping motor, and is preferably arranged on the housing.

For independent positioning of the coupling structure and the signal probe, the measuring probe for the coupling structure and the signal probe each have a separate positioning device.

The invention will be explained in more detail below with reference to the drawing. This shows in:

1 shows a schematic representation of a preferred embodiment of a measuring probe according to the invention in a measuring setup,

Fig. 2 is a plan view of the preferred embodiment of FIG. 1 and Fig. 3 is a schematic representation of a measurement setup with a vectorial network analyzer (VNA).

The illustrated in FIGS. 1 and 2, preferred embodiment of a probe according to the invention comprises a housing 10, a coupling structure 12 in the form of a contactless loop or loop probe and a signal probe 14 in the form of a signal line 16 electrically and mechanically contacting probe tip. The coupling structure 12 is formed with a first port 18 and a second port 20, which form an output path, such that it decouples an electrical signal from the signal line 16. The signal probe 14 is formed with an input 22 such that it couples an electrical signal into the signal line 16. The signal probe 14 is arranged and configured in such a way that the coupling structure 12 is in the near field of the signal line 16, ie decouples a signal without contact from the signal line 16 when the signal probe 14 electrically and mechanically contacts the signal line 16, as shown in FIG.

The signal line 16 is part of an electrical or electronic circuit on a printed circuit board 30, which comprises an electrical or electronic, embedded component under test (DUT) as well as further electrical or electronic components 26, 28. The signal line 16 is formed, for example, as a stripline.

In Fig. 3 functionally identical parts are designated by the same reference numerals as in Fig. 1, so that reference is made to the explanation of the above description of FIG. On the circuit board 30, the electronic circuit additionally comprises electronic components 32 and 34, which are designed, for example, as amplifiers, which can only be operated in the forward direction and have a very high intrinsic resistance in the other direction. The components 26, 28, 32 and 34 as well as the DUT 24 are essentially two-ported into the signal line 16 are looped. Further, 36 denotes a first position, 38 a second position, 40 a third position, 42 a fourth position, 44 a fifth position and 46 a sixth position on the printed circuit board 30. Reference levels are designated 48. FIG. 3 shows a measuring arrangement with two measuring probes according to the invention and a vectorial network analyzer 50 (VNA). The VNA 50 comprises a signal source 52, a switch 54, with a switch position I and a switch position II, a first measuring port 56, a second measuring port 58, a third measuring port 60 and a fourth measuring port 62. Denoted at 64 is a complex device resistance Z ₉ , The signal source 52 is connected via the switch 54 to an input 22 of one of the signal probes 14. The measuring ports 56, 58, 60 and 62 are connected to the outputs 18 and 20. The signal of the signal source 52 is coupled depending on the position of the switch 54 on different sides of the DUT 24 in the signal line 16 through the signal probes 14.

By means of the measuring probe according to the invention, it is possible not to conduct the power of the signal coupled into the signal line 16 across all the components 26, 28, 32, 34 to the DUT 24, but to feed it directly in front of the DUT 24 by means of the signal probes 12. After or downstream of the supply of power, the coupling structures 12 are then positioned in each case. According to the invention, the contactless coupling structure 12 and the contact-type signal probe are combined to form one unit, preferably in a housing. Another advantage of a combined probe is that an optimized combination requires significantly less space for positioning. As a rule, the distance between two measuring objects, such as the components 24, 26, 28, 32, 34 of the electronic circuit, is very limited. Another advantage is that a DC voltage supply via bias to possibly present in the probe amplifiers is possible. The use of amplifiers can improve the signal-to-noise ratio. As a result of the use of the measuring probe 14 according to the invention, the ends of the planar circuit to be examined remain open, as can be seen from FIG. When using a 7-term calibration method, the reaction of the open ends does not influence the measurement result. FIG. 2 shows by way of example how the structure of a planar microstrip circuit to be examined on the circuit board 30 is modified for the use of the combined measuring probe according to the invention. For the signaling in the exemplary embodiment shown in FIG. 2, in addition to the planar microstrip line 16, a contact surface with a via 66 to ground is provided. In another embodiment, if the measurement objects are connected to coplanar lines, no additional contact surfaces need to be provided in the circuit. Then, the shape of the feeding signal probe 14 corresponds, for example, to that of a conventional on-wafer probe connected to the non-contact probe 12 via the housing.

The combination measuring probe according to the invention comprises at least one coupling structure 12, which partially decouples an electromagnetic wave running on an external line 16, and at least one signal probe 14, which has the task of transmitting power to the external line 16. In this case, coupling structure 12 and signal probe 14 may both be contactless or contact-based or of a combination of contactless and contact-type. In other words, at least one coupling structure 12 is combined with at least one signaling measuring tip 14 to form a measuring probe unit. The mass of the two types of probe (coupling structure 12 and signal probe 14) is suitably electrically connected to each other. Preferably, the two types of probes have a common housing and a common holder.

The combination measuring probe according to the invention is particularly suitable for use in a contactless vector network analysis system, as shown in FIG. Other applications are also possible.

In an exemplary embodiment, the geometry of the contact probe 14 corresponds to the geometry of a conventional on-wafer probe.

Sample. It is important for this embodiment that the measuring tip 14 has at least one contact plate with which an electrical contact with a (planar) waveguide 16 to which the DUT 24 is electrically connected is made. The contact plates (e) are optionally connected via an inner waveguide (within the housing 10 of the measuring probe) to an outer transition (for example an SMA plug). The outer transition serves to connect the measuring tip 14 to a generator 52.

For example, the measuring tip 14 and the coupling structure are each impedance-controlled, i. the input reflection attenuation is maximized.

For example, inductive probes, capacitive probes and combinations of purely inductive and purely capacitive probes are used as the coupling structure 12 or signal probe 14. The contactless coupling structure 12 is designed, for example, as a loop probe.

In the input path 22 of the measuring tip 14 and / or in the output paths 18, 20 of the coupling structure 12 amplifiers for improving the signal quality are provided in a preferred embodiment of the invention. Thus, the combination measuring probe according to the invention becomes an active measuring probe. In the case of an active measuring probe, it may be useful to connect the measuring tip 14 and the coupling structure 12 to a direct current source (bias) in order to provide a DC voltage superimposed on the HF test signal to the amplifiers for setting the operating point.

The housing of the combination measuring probe according to the invention can be made of any materials. For example, a metal housing is provided, which is sheathed with an absorber material. Alternatively, a plastic housing or an absorber housing is provided.

The combination measuring probe according to the invention has, for example, sensors for automatic positioning or for detecting a three-dimensional position. At least one waveguide is preferably connected to the coupling structure 12, wherein the end of the waveguide forms a transition. If two waveguides are connected, one usually speaks of a probe loop. It is also possible for more than one or two waveguides to be connected to the coupling structure 12. The coupling structure 12 may also comprise individual probes (for example, capacitive probes).

The combination measuring probe according to the invention has in a preferred development a three-dimensional adjustment, so that, for example, the distance of the contactless coupling structure 12 to the waveguide 16 to which the DUT 24 is connected, can be adjusted. For example, the relative position of the coupling structure 12 to the measuring tip 14 is changed with a three-dimensional adjustment (for example, X-Y-Z linear stage). The adjustment is designed, for example, mechanically or electrically controllable. The adjustment process can be automated so that the best coupling position is always selected.

Another preferred development of the invention relates to the combination of the combination measuring probe with a position device, so that the combination measuring probe can be displaced in all dimensions or only in one or two etc. The position device is for example integrated in the housing 16 or connected via a holder with the combination measuring probe. The position device is manually operated and / or motorized, for example. It is active or passive. The position device preferably contains a control line for control.

The combination measuring probe according to the invention has, for example, two separate position devices which make it possible for the contact-type signal probe 14 and the contactless coupling structure 12 to be positioned independently of one another or for the position to be set independently of one another. The coupling structure (12) can also comprise a plurality of individual capacitive, inductive and / or inductively and capacitively coupling probes.

Claims

claims:

1. Measuring probe, in particular for a contactless vector network analysis system, comprising a housing (10) and at least one housing (10) arranged coupling structure (12), which is designed for coupling an RF signal from a signal line (16), characterized in that the housing (10) in addition at least one signal probe (14) for coupling an electrical signal in the signal line (16) is arranged.

2. Measuring probe according to claim 1, characterized in that the signal probe (14) as a signal line (16) electrically and mechanically contacting measuring tip is formed, wherein the measuring tip (14) is arranged and designed such that the coupling structure (12) At least in the near field of the signal line (16) or the signal line (16) contacted electrically and mechanically when the measuring tip (14) electrically and mechanically contacts the signal line (16).

3. Measuring probe according to claim 1, characterized in that the signal probe (14) is designed as a contactless conductor loop or loop probe.

4. Measuring probe according to claim 3, characterized in that the contactless signal probe (14) is designed as purely inductive, purely capacitive or combined inductive and capacitive probe.

5. Measuring probe according to at least one of the preceding claims, characterized in that the coupling structure (12) as the signal line (16) is formed electrically and mechanically contacting measuring tip.

6. Measuring probe according to at least one of claims 1 to 4, characterized in that the coupling structure (12) is designed as a contactless conductor loop or loop probe.

7. Measuring probe according to claim 6, characterized in that the contactless coupling structure (12) is designed as a purely inductive, purely capacitive or combined inductive and capacitive probe.

8. Measuring probe according to at least one of the preceding claims, characterized in that a ground contact of the coupling structure (12) and the signal probe (14) are electrically connected to each other.

9. Measuring probe according to at least one of the preceding claims, characterized in that the coupling structure (12) and the signal probe (14) are each executed impedance-controlled, wherein the impedances of the signal paths between the signal probe (14) and an input (22) of the signal probe ( 14) and the impedances of the signal probe (14) and the input (22) of the signal probe (14) or the impedances between the coupling structure (12) and the first port (18) of the coupling structure (12) and the second gate (20). the coupling structure (12) and the impedances of the coupling structure (12), the first port (18) of the coupling structure (12) and the second gate (20) of the coupling structure (12) are coordinated with each other such that there is a high input reflection loss.

10. Measuring probe according to at least one of the preceding claims, characterized in that an electrical signal amplifier is arranged in an input path (22) of the signal probe (14).

11. Measuring probe according to at least one of the preceding claims, characterized in that an electrical signal amplifier is arranged in at least one output path (18, 20) of the coupling structure (12).

12. Measuring probe according to claim 10 or 11, characterized in that the signal probe (14) and / or the coupling structure (12) are acted upon by a DC voltage / is.

13. Measuring probe according to at least one of the preceding claims, characterized in that the housing (10) is made of a metallic material, an absorber material and / or of a plastic.

14. Measuring probe according to at least one of the preceding claims, characterized in that the housing (10) is encased with an absorber material.

15. Measuring probe according to at least one of the preceding claims, characterized in that in addition a device for determining a distance of the coupling structure (12) from the signal conductor (16) is provided.

16. Measuring probe according to claim 15, characterized in that the device for determining the distance comprises an optical, electrical, mechanical and / or electromechanical distance sensor.

17. Measuring probe according to at least one of the preceding claims, characterized in that in addition a device for determining a position of the measuring probe is provided in the room.

18. Measuring probe according to claim 17, characterized in that the device for determining a position of the measuring probe in the room is an image sensor.

19. Measuring probe according to at least one of the preceding claims, characterized in that the measuring probe additionally has at least one positioning device for positioning the same in the room.

20. Measuring probe according to claim 19, characterized in that the positioning device has at least one positioning motor, in particular a stepping motor.

21. Measuring probe according to claim 19 or 20, characterized in that the measuring probe for the coupling structure (12) and the signal probe (14) each having a separate positioning device.

22. Measuring probe according to at least one of claims 19 to 21, characterized in that the positioning device is arranged on the housing (10).