GB2550398A - Improved signal probe - Google Patents

Abstract

A signal probe comprising one or more substrate layers 12, 14, a planar transmission line 16 disposed on at least one of the one or more substrate layers, and one or more signal contacts 20 each extending from or through an edge of at least one of the one or more substrate layers. The planar transmission line may be disposed between two substrate layers. There may be one or more circuit components 18 in electrical contact with the transmission line, at least one being arranged on one of the substrate layers and co-planar with the transmission line. The probe may have a connector 22 for connecting to an auxiliary electronic equipment. One or more conductive planes may be provided on the substrate layers, which provide insulation between the conductive planes and the transmission line. The substrate layers may comprise a dielectric material having a dielectric constant between 3 and 4 at between -55°C and +125°C and up to 20GHz.

Description

Improved Signal Probe [0001] The present invention relates to a signal probe, and in certain embodiments, to a signal probe that is particularly suited for probing, measuring and/or viewing microwave and/or gigabit signals.

BACKGROUND

[0002] Historically, gigahertz (GHz) signal frequencies have been the domain of radio and microwave engineering and were typically few and perhaps narrow band within any given system. Today, a multiplicity of broadband signals are commonly found within digital and computing systems, personal communication, media and gaming devices, and position, sensing and control systems, for example. There is therefore a growing need for probing, measuring and viewing such high speed and broadband signals.

[0003] High frequency and broadband signals typically propagate in transmission lines, where the transmitted efficiency and signal integrity is dependent upon consistent characteristic impedance along the length of the transmission line. Characteristic impedance is determined by factors including the materials of the conductors and insulators, and their geometries relative to one other and any adjacent grounds, screens or conductors. These, too, should remain consistent if signal losses and reflections are to be minimised.

[0004] Ideally, a high frequency or broadband signal is measured without significant disturbance of the signal or, by inference, the transmission lines that carry them. This would be a “non-invasive” or, more accurately, a Ίο-invasive” measurement. In principal, a contact measurement can also be DC coupled. However, a general problem associated with measurement of high frequency or broadband signals is that, often, the measurement itself alters the very signal being measured.

[0005] Prior art microwave probing solutions have tended to be bulky, too invasive, too expensive, with poor measurement repeatability and, in some cases, have also been mechanically or electrically fragile. As a result, transmission line(s) under-test have often been physically interrupted and either re-routed to or power divided to a terminating measurement instrument. Whilst measurement integrity can be very high using this method, inconvenience can also be high and impractical in many cases. For example, signal interruption, delay or amplitude reduction may interrupt system functionality. Transmission line adaption to a feedline (and, ultimately, to a measurement instrument) may not be practical or may be very costly. For example, this may require the interruption and subsequent repair of fine pitch or buried PCB tracking into a coaxial launch connector. In certain arrangements, multiple system signal paths may need to be interrupted and fitted with matching pick-off networks and propagation delays.

[0006] It is an object of certain embodiments of the present invention to overcome certain disadvantages associated with the prior art.

[0007] It is an object of certain embodiments of the present invention to provide a signal probe that is capable of probing high frequency (such as microwave or gigabit frequencies) and/or broadband signals whilst being less invasive than some prior art arrangements.

BRIEF SUMMARY OF THE DISCLOSURE

[0008] In accordance with an aspect of the present invention there is provided a signal probe comprising: one or more substrate layers; a planar transmission line arranged in electrical contact with the transmission line and disposed on at least one of the one or more substrate layers; and one or more signal contacts each extending from or through an edge of at least one of the one or more substrate layers.

[0009] The arrangement of the signal contact(s) relative to the substrate layers may allow each signal contact to be mechanically supported whilst avoiding surrounding the signal contact with dielectric or conductive material. That is, a low capacitance support for the signal contact may be provided.

[0010] In combination, these features serve to provide a signal probe that may transmit microwave (and other high frequency) signals with a high integrity and be less invasive than certain prior art arrangements.

[0011] The one or more substrate layers may comprise a plurality of substrate layers arranged in a stacked configuration. The planar transmission line may be at least partially disposed between two adjacent substrate layers. As such, the transmission line may be a “buried” transmission line disposed between two adjacent substrate layers. This configuration may permit controlled and uniform transmission of high frequency signals.

[0012] The signal probe may further comprise one or more circuit components arranged in electrical contact with the transmission line. At least one of the plurality of circuit components may be arranged on one of the substrate layers in a co-planar configuration with the transmission line.

[0013] The one or more signal contacts may be arranged in a co-planar configuration with the transmission line. A co-planar configuration may minimize mismatch and avoid the requirement for the signal to step through 90° as it propagates through the signal probe.

[0014] In certain embodiments, the one or more signal contacts may extend from between two of the substrate layers.

[0015] In certain embodiments, the one or more signal contacts may comprise a male component. The male component may comprise a signal pin. The signal pin may extend parallel to the planes of the one or more substrate layers.

[0016] In other embodiments, the one or more signal contacts may comprise a female component configured to receive a male component. The female component may comprise a socket configured to receive a pin.

[0017] The signal probe may further comprise a connector for electrically connecting the signal probe to an auxiliary electronic component. In certain embodiments, the connector may be a co-axial connector. The connector may be arranged in a co-planar configuration with the transmission line.

[0018] The signal probe may further comprise one or more ground contacts arranged in electrical contact with the transmission line. The one or more ground contacts may be arranged in a co-planar configuration with the transmission line. The one or more ground contacts may extend from an edge of the one or more of the substrate layers. Each of the one or more ground contacts may extend parallel to the planes of the substrate layers. In certain embodiments, the one or more ground contacts may comprise a ground pin. The one or more ground pins may be parallel to the one or more signal pins. In certain embodiments, the signal probe may comprises one signal contact and two ground contacts. In other embodiments, the signal probe may comprise two signal contacts and two ground contacts.

[0019] In certain embodiments, the plurality of circuit components may be provided on a first of the substrate layers, and a second adjacent one of the substrate layers may include an aperture overlying the plurality of circuit components.

[0020] The signal probe may further comprise one or more conductive planes arranged to provide shielding to at least the transmission line, the one or more conductive planes may be electrically insulated from the transmission line. The one or more conductive planes may be provided on the one or more substrate layers and the one or more substrate layers may provide electrical insulation between the conductive planes and the transmission line. In certain embodiments, the conductive planes may comprise copper.

[0021] The transmission line may be provided on one of the substrate layers that comprises a dielectric material having a dielectric constant of between 3 and 4 at temperatures between -55°C and +125°C and frequencies up to 20 GHz.

[0022] In accordance with another aspect of the present invention, there is provided a kit comprising an auxiliary electronic component and the signal probe described above. The electronic component may comprise a measurement instrument. The electronic component may comprise one of an oscilloscope, a spectrum analyser, a network analyser or a milli-voltmeter, and, optionally, may be a PC-based instrument. In certain embodiments, the electronic component may have a 50 ohm terminating input.

[0023] In accordance with another aspect of the present invention, there is provided an interconnect assembly comprising at least two signal probes as described above, wherein the signal contact of one of the signal probes is a male component and the signal contact of another of the signal probes is a female component that is configured to receive the male component.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a schematic cross sectional view of a signal probe according to an embodiment of the present invention;

Figure 2 is an exploded view of a signal probe according to an embodiment of the present invention;

Figure 3 is a perspective view of a signal probe according to an embodiment of the present invention;

Figure 4 is a circuit diagram illustrating the electronic configuration of a signal probe according to an embodiment of the present invention; and

Figure 5 is a schematic representation of a kit according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0025] A signal probe 10 according to an embodiment of the present invention is schematically shown in cross section in Figure 1. The signal probe 10 extends along a longitudinal axis 100 and includes a first substrate layer 12 and a second substrate layer 14 disposed on the first substrate layer 12 in a stacked configuration. That is, the second substrate layer 14 is disposed on the first substrate layer 12 such that the plane of the second substrate layer 14 (which is parallel to the longitudinal axis 100) is parallel to the plane of the first substrate layer 12. The first and second substrate layers 12,14 are bonded, soldered or otherwise fixed relative to one another.

[0026] The first and second substrate layers 12,14 comprise a dielectric material. In certain embodiments, the dielectric material is suitable for microwave applications. In certain embodiments, the dielectric material of the first substrate layer 12 and/or second substrate layer 14 has a dielectric constant of between 3 and 4 at temperatures between -55°C and +125°C and/or at frequencies up to 20 GHz. In certain embodiments, the dielectric material of the first substrate layer 12 and/or second substrate layer 14 may comprise dielectric material available commercially under the name l-Tera® from Isola®.

In alternative embodiments, the first substrate layer 12 and/or second substrate layer 14 may be made of other suitable materials. In certain embodiments, the second substrate layer 14 may comprise a different dielectric material relative to the first substrate layer 14.

[0027] A planar transmission line 16 extends along a surface of the first substrate layer 12 between the first substrate layer 12 and the second substrate layer 14. The transmission line 16 comprises a layer or track of conductive material and is capable of transmitting a high frequency signal. Suitable conductive materials for forming the transmission line 16 include, but are not limited to, copper and gold.

[0028] Either or both of the first and second substrate layers 12,14 may additionally include a conductive layer (not shown) on respective outer surfaces 12a, 14a (i.e. surfaces of the first and second substrate layers 12,14 that are not adjacent to one another). Such conductive layers may provide a shielding effect to the transmission line 16 sandwiched between the first and second substrate layers 12,14 and permit transmission of high frequency signals therethrough.

[0029] The signal probe 10 includes a signal contact in the form of a signal pin 20. The signal pin 20 shown in Figure 1 is elongate in a direction parallel to the longitudinal axis 100 and extends away from the first and second substrate layers 12,14 along the longitudinal axis 100. The signal pin 20 is parallel to the planes of both of the first and second substrate layers 12, 14. In the non-limiting embodiment shown in Figure 1, the signal pin 20 extends from an edge of the second substrate layer 14 and extends beyond the edge of the first substrate layer 12. In certain embodiments, the signal contact may extend from or through an edge of at least one of the one or more substrate layers.

[0030] The signal pin 20 is electrically connected to the transmission line 16 and is arranged in a co-planar configuration therewith. In alternative embodiments, the signal contact may be provided in a form other than a pin, but still preferably arranged in a co- planar configuration with the transmission line 16 and extending away from the substrate layers 12,14. In the non-limiting embodiment shown in Figure 1, the signal pin 20 is received in a recess of the second substrate layer 14 such that the signal pin 20 is disposed on the first substrate layer 12 and partly surrounded and supported by both of the first and second substrate layers 12,14.

[0031] The second substrate layer 14 has internal edges 14b defining an aperture that overlies a portion of the first substrate layer 12. A plurality of circuit components 18 is disposed on the first substrate layer 12 in the portion that the aperture of the second substrate layer 14 overlies. The plurality of circuit components 18 are electrically connected to the transmission line 16 and are arranged in a co-planar configuration therewith. That is, the circuit components 18 and transmission line 16 are arranged in the same plane and, consequently, the electrical transmission path between the circuit components 18 and the transmission line 16 is planar. The plurality of circuit components 18 may be any suitable circuit components including, but not limited to, any one or more of resistors, capacitors, inductors, transistors, diodes, microwave amplifiers, comparators, bolometers, samplers, analogue to digital converters and other digital signal devices.

[0032] The co-planar arrangement of the signal pin 20, transmission line 16 and plurality of circuit components 18 is advantageous for microwave (and other high frequency) applications as it minimizes mismatch and avoids the requirement for the signal to step through 90° as it propagates through the signal probe 10.

[0033] A connector 22 is provided at an end of the signal probe 10 distal to the signal pin 20. The connector 22 is electrically connected to the transmission line 16 by a bridge portion 22a. The connector 22 permits the electrical connection of the signal probe 10 to an auxiliary electronic component, such as an oscilloscope. In certain embodiments, the connector 22 is a co-axial connector 22 facilitating the connection of a co-axial cable to the signal probe 10.

[0034] An exploded view of an embodiment of the signal probe 10 is shown in Figure 2. The signal probe 10 of Figure 2 includes the components described above in relation to Figure 1 and additionally includes a cap 24, and a casing in two casing parts 26a,26b. The cap 24 may be fastened, adhered or otherwise fixed to the second substrate layer 14. As such, the cap 24 provides additional structural support to the signal pin 20. In certain embodiments, the cap 24 may comprise a dielectric material which may or may not be the same dielectric material as the first and second substrate layers 12,14. In certain embodiments, the cap 24 may comprise FR-4 substrate material. The dielectric material may be provided in one or several stacked dielectric layers (e.g. in a similar or identical manner to the first and second substrate layers 12,14). The stacked dielectric layers of the cap 24 may include conductive layers on outer and/or intermediate surfaces of the stack and such conductive layers may provide further shielding to the transmission line 16. The one or more dielectric layers of the cap 24 may include a recess or other formation for receiving or otherwise providing structural support to the signal pin 20 and/or the connector 22. In such an arrangement, the signal pin 20 may extend from edges of one or more of the first substrate layer 12, the second substrate layer 14, or one or more of the dielectric layers of the cap 24. In certain embodiments, at least a portion of the signal pin 20 (or other signal contact) may be held captive between a substrate layer (e.g. the first substrate layer 12) and a layer of the cap 24. Similarly, the one or more dielectric layers of the cap 24 may include a recess or other formation for overlying the circuit components 18. That is, a recess in the cap 24 may align with the aperture defined by edges 14b of the second substrate layer 14 to extend the height of the aperture. This may accommodate any circuit (or other) components within the aperture that may extend beyond the height of the second substrate layer 14.

[0035] The casing parts 26a,26b may be assembled around the internal components of the signal probe 10 and provide an ergonomic surface for handling of the signal probe 10.

[0036] Figure 3 shows a perspective view of an embodiment of the signal probe 10 wherein the cap 24 is fixed to the first and second substrate layers 12,14 and provides mechanical support to the signal pin 20.

[0037] In the embodiments shown in Figures 2 and 3, the signal probe 10 additionally includes ground contacts in the form of a pair of ground pins 21a,21b. The ground pins 21a,21b may be mounted to the signal probe 10 in the same manner as the signal pin 20 and extend from the first and second substrate layers 12,14. In the embodiment shown in Figures 2 and 3, the ground pins 21 a,21b are parallel to the signal pin 20. The ground pins 21a,21b are also preferably mounted to the transmission line 16 in a co-planar configuration. The ground pins 21 a,21b may be telescopic or otherwise adjustable so that their length may be altered.

[0038] In certain embodiments of the present invention, the signal contact (and/or ground contact(s)) may be provided in a form other than a pin. For example, any of the signal contact and/or ground contacts may be provided as a socket which may, for example, be configured to receive a pin. Indeed, any suitable female or male component may form the signal contact and/or ground contact(s). Furthermore, any number of signal contacts and/or ground contacts may be provided.

[0039] In a certain aspect of the present invention, there is provided an interconnect assembly comprising two signal probes in accordance with embodiments of the invention, where the signal contact of one of the signal probes comprises a male component (e.g. a pin) and the signal contact of the other of the signal probes comprises a female component (e.g. a socket). In this aspect, the signal probes may form a multi-way connector that is capable of operating at high frequencies. The shape of the signal probes (e.g. the profile of the substrate layers) may be configured to permit close mating of the two signal probes when the male component is received by the female component.

[0040] Figure 4 shows an example electronic configuration of a signal probe 10 according to an embodiment of the present invention. As shown, the transmission line 16 extends between the signal pin 20 and the ground pins 21 a,21b, and multiple terminals of the connector 22 via circuit components 18. In the example shown in Figure 4, the circuit components includes a first resistor R1 arranged in parallel with a capacitor C1, and a second resistor R2 arranged in series with the first resistor R1 and capacitor C1. In other embodiments of the present invention, alternative electronic configurations may be utilized.

[0041] Figure 5 shows a kit 200 according to an embodiment of the present invention.

The kit 200 includes the signal probe 10, an oscilloscope 202 (e.g. a PC-based oscilloscope) connected to the signal probe 10 and a computer 204 operatively connected to the oscilloscope 202. In use, signals measured by the signal probe 10 may be processed by the oscilloscope 202 and/or computer 204. Additionally or alternatively, the computer 204 may provide a display, control interface and/or memory for the oscilloscope. Certain aspects of the present invention may relate to other kits of parts which may consist of or include the signal probe 10 and an electronic component. In certain embodiments, the electronic component may comprise a measurement instrument, which, besides traditional and PC-based oscilloscopes, may include one or more of a spectrum analyser, a network analyser or a milli-voltmeter (which may or may not be PC-based instruments).

In certain embodiments, the electronic component may be any suitable electronic component having a 50 ohm terminating input.

[0042] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0043] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments.

The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0044] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims (35)

1. A signal probe comprising: one or more substrate layers; a planar transmission line arranged in electrical contact with the transmission line and disposed on at least one of the one or more substrate layers; and one or more signal contacts each extending from or through an edge of at least one of the one or more substrate layers.

2. The signal probe of claim 1, wherein the one or more substrate layers comprises a plurality of substrate layers arranged in a stacked configuration.

3. The signal probe of claim 2, wherein the planar transmission line is at least partially disposed between two adjacent substrate layers.

4. The signal probe of any preceding claim, further comprising one or more circuit components arranged in electrical contact with the transmission line, at least one of the plurality of circuit components being arranged on one of the substrate layers in a co-planar configuration with the transmission line.

5. The signal probe of any preceding claim, wherein the one or more signal contacts are arranged in a co-planar configuration with the transmission line.

6. The signal probe of any preceding claim, wherein the one or more signal contacts extend from between two of the substrate layers.

7. The signal probe of any preceding claim, wherein the one or more signal contacts comprises a male component.

8. The signal probe of claim 7, wherein the male component comprises a signal pin.

9. The signal probe of claim 8, wherein the signal pin extends parallel to the planes of the one or more substrate layers.

10. The signal probe of any of claims 1 to 6, wherein the one or more signal contacts comprises a female component configured to receive a male component.

11. The signal probe of claim 10, wherein the female component comprises a socket configured to receive a pin.

12. The signal probe of any preceding claim, further comprising a connector for electrically connecting the signal probe to an auxiliary electronic component.

13. The signal probe of claim 12, wherein the connector is a co-axial connector.

14. The signal probe of claim 12 or 13, wherein the connector is arranged in a co-planar configuration with the transmission line.

15. The signal probe of any preceding claim, further comprising one or more ground contacts arranged in electrical contact with the transmission line.

16. The signal probe of claim 15, wherein the one or more ground contacts are arranged in a co-planar configuration with the transmission line.

17. The signal probe of claim 15 or 16, wherein the one or more ground contacts extend from an edge of the one or more of the substrate layers.

18. The signal probe of any of claims 15 to 17, wherein each of the one or more ground contacts extends parallel to the planes of the substrate layers.

19. The signal probe of any of claims 15 to 18, wherein the one or more ground contacts comprise a ground pin.

20. The signal probe of claim 19 when dependent on claim 8, wherein the one or more ground pins are parallel to the one or more signal pins.

21. The signal probe of claim 19 or 20 when dependent on claim 8, comprising one signal contact and two ground contacts.

22. The signal probe of claim 19 or 20 when dependent on claim 8, comprising two signal contacts and two ground contacts.

23. The signal probe of claim 4 or any of claims 5 to 22 when dependent on claim 4, wherein the plurality of circuit components are provided on a first of the substrate layers, and a second adjacent one of the substrate layers includes an aperture overlying the plurality of circuit components.

24. The signal probe of any preceding claim, further comprising one or more conductive planes arranged to provide shielding to at least the transmission line, the one or more conductive planes being electrically insulated from the transmission line.

25. The signal probe of claim 24, wherein the one or more conductive planes are provided on the one or more substrate layers and the one or more substrate layers provide electrical insulation between the conductive planes and the transmission line.

26. The signal probe of claim 24 or 25, wherein the conductive planes comprise copper.

27. The signal probe of any preceding claim, wherein the transmission line is provided on one of the substrate layers that comprises a dielectric material having a dielectric constant of between 3 and 4 at temperatures between -55°C and +125°C and frequencies up to 20 GHz.

28. A kit comprising an auxiliary electronic component and the signal probe of any preceding claim.

29. The kit of claim 28, wherein the electronic component comprises a measurement instrument.

30. The kit of claim 28 or 29, wherein the electronic component comprises one of an oscilloscope, a spectrum analyser, a network analyser or a milli-voltmeter.

31. The kit of any of claims 28 to 30, wherein the electronic component is a PC-based instrument.

32. The kit of any of claims 28 to 31, wherein the electronic component has a 50 ohm terminating input.

33. An interconnect assembly comprising at least two signal probes according to any of claims 1 to 27, wherein the signal contact of one of the signal probes is a male component and the signal contact of another of the signal probes is a female component that is configured to receive the male component.

34. A signal probe substantially as hereinbefore described with reference to the accompanying drawings.

35. A kit substantially as hereinbefore described with reference to the accompanying drawings.