WO2021058836A1

WO2021058836A1 - Rf and millimeter-wave probe array

Info

Publication number: WO2021058836A1
Application number: PCT/EP2020/077269
Authority: WO
Inventors: Wane SIDINA; Quang Hung Tran
Original assignee: Ev Technologies
Current assignee: Ev Technologies
Priority date: 2019-09-29
Filing date: 2020-09-29
Publication date: 2021-04-01
Anticipated expiration: 2022-03-29
Also published as: EP4062182A1

Abstract

The present disclosure relates to a probing device comprising: at least two probing elements (102, 102'), each probing element comprising a spin-wave sensor (104) mounted on a support substrate, each spin-wave sensor comprising at least four connection terminals electrically coupled to connection pads on the support substrate.

Description

DESCRIPTION

RF and Millimeter-Wave Probe Array

Technical field

[0001] The present disclosure relates generally to the field of probe arrays, and in particular to a probe array for testing and/or characterizing devices emitting radiofrequency (RF) and millimeter-wave signals.

Background art

[0002] The automatized testing and validation of 5G (Fifth Generation) and IoT (Internet of Things) communication devices requires appropriate instruments capable, for example, of evaluating power integrity (PI), signal integrity (SI), and conformity with EMC (Electro-Magnetic Capability) and EMI (Electro-Magnetic Interference) specifications. Indeed, PI, SI, EMC and EMI performance is a critical issue for new generation communications systems that are required to have very high data transmission rates, low energy consummation, and a strong immunity to undesirable disturbances.

[0003] Near-field sensing of the emissions of circuits and systems having integrated antennas provides a mechanism to verify EMC/EMI conformity, perform OTA (Over The Air) testing and perform diagnosis of EMC/EMI and power and signal integrity problems.

[0004] There is, however, a need in the art for a solution for permitting such near-field sensing to be performed in an industrial setting in a precise and effective manner.

[0005] Conventional and traditional RF and Microwave near field probing solutions are built using metallic structures to sense local electromagnetic fields. The metallic probes are placed at relatively short distances from the antenna under test (AUT) or device under test (DUT), which is subject to unavoidable interactions and interferences between the AUT (DUT) and the sensing probes. Furthermore, the commercially available probe dimensions, mainly limited by the packaging and module based-integration, are on the order of millimeter scale. Such probes do not operate at DC, thus no measurement of DC power or energy density is possible. In addition, the available field scanning techniques are generally combined with mechanical motion using step-motors leading to non- negligible uncertainties with significant measurement execution time not compatible with industrial test and characterization needs.

[0006] Because of these critical limitations, traditional scanning technologies have been unable to meet the requirements of RF and Microwave multi-scale Chip-Package-PCB near field imaging, antenna near field characterization, and medical/biomedical applications.

Summary of Invention

[0007] It is an aim of embodiments of the present disclosure to at least partially address one or more needs in the art.

[0008] According to one aspect, there is provided a probing device comprising: at least two probing elements, each probing element comprising a spin-wave sensor mounted on a support substrate, each spin-wave sensor comprising at least four connection terminals electrically coupled to connection pads on the support substrate.

[0009] According to one embodiment, each probing element is a hybrid sensor further comprising an antenna forming an RF/millimeter-wave sensor.

[0010] According to one embodiment, the antenna has at least first and second connection terminals, and wherein the first connection terminal of the antenna is electrically connected to a first of the at least four connection terminals of the spin-wave sensor, and the second connection terminal of the antenna is electrically connected to a second of the at least four connection terminals of the spin-wave sensor.

[0011] According to one embodiment, the spin-wave sensors of first and second ones of the probing elements are orientated to receive signals of opposite polarizations to each other.

[0012] According to one embodiment, the antenna of each probing element is a dipole antenna, the dipole antennas of the first and second probing elements being orientated to receive signals of opposite polarizations to each other.

[0013] According to one embodiment, two of the at least four connection pads are coupled to DC biasing rails, configured to receive a DC biasing voltage.

[0014] According to one embodiment, the support substrate comprises a shielding layer formed of a metal, and wherein each pad is coupled to a via passing through an opening in the shielding layer.

[0015] According to one embodiment, the at least two probing elements form an array of at least four columns and at least four rows.

[0016] According to one embodiment, each probing element further comprises at least one connector mounted on the support substrate, the connector comprising an outer cylindrical conductive portion coupled, for example, to a ground rail, and a central conductive portion surrounded by and insulated from the outer cylindrical portion and configured to receive at least one signal received by the probing element.

[0017] According to a further aspect, there is provided a test system comprising: the above probing device; and a control board coupled to the probing device, the control board comprising at least one digital to analog converter configured to generate a voltage signal for biasing one or more of the spin-wave sensors.

[0018] According to one embodiment, the control board further comprises: at least two analog to digital converters configured to convert signals received by one or more of the probing devices into digital signals; and at least two mixers configured to down-convert the frequencies of the digital signals .

[0019] According to one embodiment, the test system further comprises one or more multiplexers configured to route the signals received by the one or more probing devices to the at least two analog to digital converters.

[0020] According to a further aspect, there is provided a test chamber comprising at least four walls defining volume for the placement of a device under test, each wall comprising the above probe array configured to receive emissions from the device under test.

[0021] According to one embodiment, the test chamber further comprises: at least one thermal camera configured to capture thermal images of the device under test; and/or at least one visible-light camera configured to capture images of the device under test.

[0022] According to one aspect, there is provided a system including a sensing solution with the ability to measure in 3D stochastic electromagnetic fields using Quantum sensing (e.g., NV-based) hybridized with Spin-wave/Hall-sensors and RF/microwave sensors. [0023] According to one embodiment, the system comprises a thermal camera for extracting heat maps and/or combined with visual camera for extracting a DUT layout and design features.

[0024] According to one embodiment, the system is combined with Smart Built-in-Self-Test based Nonlinear sensing and calibration with multi-level signal processing.

[0025] According to one embodiment, the system is combined with DC-RF correlators for sensing of stochastic signals.

[0026] According to one embodiment, the system is configured to extracting power densities, energy densities and entropy.

[0027] According to one embodiment, the system comprises the use of step motors for increased spatial resolution and improved accuracy.

[0028] According to one embodiment, the system is configured to perform simultaneous extractions of all polarizations for 3D Field-Field correlations.

[0029] According to one embodiment, the system is configured to perform sensing and calibration both in transmit and receive modes.

[0030] According to one embodiment, the system comprises analog to digital converters (ADCs), such as high speed ADCs, that are for example configured to support pipelining and interleaved architecture topologies for time-domain and frequency-domain based signal processing.

[0031] According to one embodiment, the system is for example configured to perform liquid-based broadband calibration for SAR (Specific-Absorption-Rate) based measurement and characterization .

[0032] According to one embodiment, the system comprises broadband delay lines, power-combiners and splitters for accurate phase and amplitude compensations with controlled AM-AM and AM-PM distortions or with acoustic waves based sensors for implementation of controlled digital filtering and mixed-signal correlators.

Brief description of drawings

[0033] The foregoing features and advantages, as well as others, will be described in detail in the following description of specific embodiments given by way of illustration and not limitation with reference to the accompanying drawings, in which:

[0034] Figure 1 schematically illustrates a probe array comprising spin-wave sensors according to an example embodiment of the present disclosure;

[0035] Figure 2 schematically illustrates an example of the probe array of Figure 1;

[0036] Figure 3A is a top view of a spin-wave sensor of Figure 1 according to an example embodiment of the present disclosure;

[0037] Figure 3B is a cross-section view of a pair of spin- wave sensors mounted on a support substrate according to an example embodiment of the present disclosure;

[0038] Figure 4A schematically illustrates the spin-wave sensor of Figure 3 according to an example in which it is referenced to ground;

[0039] Figure 4B schematically illustrates the spin-wave sensor of Figure 3 according to an example in which it is biased by a DC voltage;

[0040] Figure 5 schematically illustrates a pair of probing elements and a biasing circuit according to an example embodiment; [0041] Figure 6 schematically illustrates the pair of probing elements and a biasing circuit according to yet a further example embodiment;

[0042] Figure 7 schematically illustrates a system comprising the probe array and a control board according to an example embodiment of the present disclosure;

[0043] Figure 8 schematically illustrates a readout circuit for a probe array according to an example embodiment of the present disclosure;

[0044] Figure 9A is a perspective view of a front side of a spin-wave connection interface according to an example embodiment of the present disclosure;

[0045] Figure 9B is a perspective view of a back side of the spin-wave connection interface of Figure 9A;

[0046] Figure 9C is a perspective view of the front side of the spin-wave connection interface of Figure 9A with a connector mounted thereon;

[0047] Figure 9D is a cross-section view of the spin-wave connection interface of Figure 9C;

[0048] Figure 10 is a perspective view of the back side of a spin-wave connection interface including DC biasing according to an example embodiment of the present disclosure;

[0049] Figure 11 is a perspective view of a front side of a connection interface for a pair of spin-wave sensors with DC biasing according to an example embodiment of the present disclosure;

[0050] Figure 12A is a perspective view of a front side of a connection interface for a pair of spin-wave sensors according to a further example embodiment of the present disclosure; [0051] Figure 12B is perspective view of a back side of the connection interface of Figure 12A;

[0052] Figure 13A is a perspective view of a front side of a connection interface for a spin-wave sensor and an RF/millimeter wave sensor with DC biasing according to an example embodiment of the present disclosure;

[0053] Figure 13B is a perspective view of a back side of the connection interface of Figure 13A;

[0054] Figure 14A is a perspective view of a connection interface for a pair of spin-wave sensors with DC biasing according to a further example embodiment of the present disclosure;

[0055] Figure 14B is an underside view of the connection interface of Figure 14A;

[0056] Figure 15A is a perspective view of a connection interface for a pair of spin-wave sensors with DC biasing, a pair of RF/millimeter wave sensors, and a pair of loop sensors according to a further example embodiment of the present disclosure;

[0057] Figure 15B is an underside view of the connection interface of Figure 15A;

[0058] Figure 16 is a perspective view of a test chamber according to an example embodiment of the present disclosure;

[0059] Figure 17 schematically represents a test system comprising the test chamber of Figure 16;

[0060] Figure 18 illustrates a probe array comprising patch antennas according to an example embodiment of the present disclosure;

[0061] Figure 19 is graph representing non-linear DC-RF correlation for electromagnetic- field based programmable arrays using hybrid RF/millimeter-wave and spin-wave sensors; and

[0062] Figure 20 is a graph comparing sensor technologies. Description of embodiments

[0063] Like features have been designated by like references in the various figures. In particular, the structural and/or functional features that are common among the various embodiments may have the same references and may dispose identical structural, dimensional and material properties.

[0064] Unless indicated otherwise, when reference is made to two elements connected together, this signifies a direct connection without any intermediate elements other than conductors, and when reference is made to two elements coupled together, this signifies that these two elements can be connected or they can be coupled via one or more other elements .

[0065] In the following disclosure, unless indicated otherwise, when reference is made to absolute positional qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or to relative positional qualifiers, such as the terms "above", "below", "higher", "lower", etc., or to qualifiers of orientation, such as "horizontal", "vertical", etc., reference is made to the orientation shown in the figures, or to a probe array as orientated during normal use.

[0066] Unless specified otherwise, the expressions "around", "approximately", "substantially" and "in the order of" signify within 10 %, and preferably within 5 %.

[0067] Figure 20 is a graph comparing several magnetic field sensing techniques, and substantially reproduces a graph presented in the Ph.D dissertation by E. 0. Schafer-Nolte entitled "Development of a diamond-based scanning probe spin sensor operating at low temperature in ultra high vacuum", Inst. Physical., Univ., Stuttgart, Germany, 2014.

[0068] Figure 1 schematically illustrates a probe array 100 comprising spin-wave sensors according to an example embodiment of the present disclosure. The array 100 comprises q lines (LINES) and r rows (ROWS) of probing elements 102, 102' where q and r are from example each equal to at least two, and for example to at least four. In some embodiments, a probing device could however, comprise only a single pair of probing elements 102, 102'.

[0069] The probing elements 102 and 102' are for example orientated in an opposite manner from each other in order to receive signals of opposite polarizations, the elements 102 for example being adapted to receive signals of X-polarization, and the elements 102' for example being adapted to receive signals of Y polarization. In the example of Figure 1, all of the probing elements 102, 102' have the same orientation as each other, and the elements of neighboring rows have opposite polarizations .

[0070] Each probing element 102, 102' for example comprises a spin-wave sensor 104. As known by those skilled in the art, a spin-wave sensor, also known as a spin-electronic sensor, Hall-sensor, or magnetic AMR/PHR (Anisotropic Magneto- Resistance/Planar Hall Resistance), is a device that is sensitive to magnetic fields. For example, such a device is described in more detail in the European patent application published as EP3208627 by F.TERKI et al. entitled "Measurement system and method for characterizing at least one single magnetic object", the contents of which is hereby incorporated by reference. [0071] Each probing element 102, 102' is for example a device having four contact terminals that are respectively coupled for example to a point of a corresponding one of four quarter surfaces of a detection coil of the sensor. In some embodiments, among the four contacts, two diagonally opposite contacts form biasing contacts that are coupled to a ground voltage or to a biasing voltage, which is for example a DC biasing voltage, or a voltage signal having a relatively low frequency, such as in the kHz range or less. The remaining two diagonally opposite contacts form output nodes of the sensor 104 that present an output signal in the form of a voltage difference that varies as a function of the detected magnetic field. Figure 1 illustrates an example in which the biasing contacts of each spin-wave sensor 104 receive a corresponding DC biasing voltage, which is for example generated by a control circuit (CONTROL) 106. In some embodiments, each probing element 102, 102' receives a dedicated DC biasing voltage, allowing for example for interference between neighboring cells in the array to be cancelled to some extent.

[0072] In the example of Figure 1, each of the probing elements 102, 102' is a hybrid element that combines magnetic field detection with electric field detection. For example, each of the probing elements comprises at least one RF/millimeter wave sensor 108. For example, the RF/millimeter wave sensor comprises a dipole antenna having first and second antenna portions. The dipole antenna of each probing element is for example orientated so as to receive the same signal polarization as the spin-wave sensor 104 of the probing element. Thus, the dipole antennas 108 of the probing elements 102 are for example orientated to receive X-polarized signals, and the dipole antennas 108 of the probing elements 102' are for example orientated to receive Y-polarized signals. [0073] Furthermore, in some examples, the antenna portions of the dipole antenna 108 of each probing element are electrically connected to the biasing contacts of the sensor. It would also be possible to provide separate paths for the RF/millimeter wave sensor 108 and the spin-wave sensor 104, allowing fully parallel operation of these devices.

[0074] The probing elements 102, 102' for example permit a correlation of DC and RF responses based on non-linearities of the probing array scanning system for an accurate extraction of parameters such as BER (bit error rate) and EVM as a function of frequency, modulation and data rate; spectral mask and flatness; occupied bandwidth; phase noise; I-Q imbalance; clock frequency offset; center frequency leaking; out-of-band noise, adjacent channel couplings or timing, jitter, etc. Such correlating techniques are for example described in more detail in the publication by Q.H. Tran, S. Wane, F. Terki, D. Bajon, A. Bousseksou, J. A. Russer, P. Russer, entitled "Toward Co-Design of Spin-Wave Sensors with RFIC Building Blocks for Emerging Technologies", 2018 2nd URSI Atlantic Radio Science Meeting (AT-RASC), the contents of this publication being hereby incorporated by reference. Furthermore, it is possible to perform wireless measurements of power levels and energy density levels at DC and RF/Microwave frequencies, and entropy extraction, as described for example in more detail in the publication by S. Wane et al. entitled "Energy-Geometry-Entropy Bounds aware Analysis of Stochastic Field-Field Correlations for Emerging Wireless Communication Technologies", URSI General Assembly Commission, New Concepts in Wireless Communications, Montreal 2017), the contents of this publication being hereby incorporated by reference.

[0075] Figure 2 schematically illustrates an example of another probe array 200 similar to that of Figure 1, but in which the probing elements 102 are arranged in a checker board pattern with respect to the elements 102'. In such a case, a diagonal separation DC between the elements 102, and the diagonal separation DU between the elements 102', are for example identical, and for example equal to between 1 mm and 20 mm, and for example to between 2 mm and 5 mm.

[0076] Figure 3A is a top view of a spin-wave sensor 104 according to an example embodiment of the present disclosure. The sensor 104 for example has a substantially square footprint, and width of between 1 and 10 mm, although other shapes and dimensions would be possible. In the example of Figure 3A, the sensor 104 has a width of around 2.5 mm. The four contacts 302, 304, 306 and 308 are visible on the top surface of the sensor 104, close to respective corners of the sensor 104.

[0077] Furthermore, the conductive coil 310 of the sensor is visible, and Figure 3A illustrates one possible patterning of this coil. In particular, the coil 310 is for example formed over a square-shaped area which is positioned in the middle of the sensor 104 at an angle of 45 degrees with respect to the edges of the sensor. The coil 310 for example comprises, in each quadrant of its area, a serpentine pattern, adjacent quadrants having serpentines running perpendicular to each other, and diagonally opposing quadrants having serpentines running the same direction as each other. A point of the coil between each of the adjacent quadrants is connected to a corresponding one of the contacts 302, 304, 306, 308. Of course, other patterns of the coil 310 would be possible, such as the one described in the patent application EP 3208627 referenced above.

[0078] Figure 3B is a cross-section view of a pair of adjacent spin-wave sensors 104 mounted on a front side of a support substrate 312. For example, the contacts of each sensor 104 are wire-bonded to contact pads 314 formed on the surface of the substrate 312, two such wire-bonds for each sensor being illustrated in Figure 3B. In some embodiments, to avoid interference with the sensors 104, electrical tracks for propagating the signals received by the sensors 104 are positioned on a back side of the support substrate 312, and the support substrate 312 for example comprises a shielding layer 316, for example made of metal. The contact pads 314 are for example connected to metal tracks 318 on the back side using vias 320, which for example pass through corresponding openings in the shielding layer 316.

[0079] Figure 4A schematically illustrates the spin-wave sensor 104 of Figure 3A according to an example in which it is referenced to ground, in other words the contacts 302 and 308 being coupled to ground rails, and the contacts 304 and 306 providing an output signal (SIGNAL) of the sensor.

[0080] Figure 4B schematically illustrates the spin-wave sensor 104 of Figure 3A according to an example in which it is biased by a DC biasing voltage, in other words the contacts 302 and 308 receiving a DC biasing voltage (DC BIAS), and the contacts 304 and 306 providing an output signal (SIGNAL) of the sensor.

[0081] Figure 5 schematically illustrates a pair of probing elements 102, 102', one for X-polarization and one for Y- polarization, and a biasing circuit (BIASING) 502 for biasing at least the spin-wave sensors 104 of the elements 102, 102' with a DC biasing voltage, as explained above. For example, the probing elements are two of the elements of the probe array 100 of Figure 1, or a pair of elements that together form a probing device. There are thus four input terminals to each of the elements 102, 102' of Figure 5, in which pairs A and D of terminals of the respective devices 102, 102' are for outputting the detected signal from the spin-wave sensor 104, and further pairs B and C of terminals of the respective devices 102, 102' are for outputting the detected signal from the RF/millimeter wave sensors 108 and for the application of a biasing voltage.

[0082] Figure 6 schematically illustrates the pair of probing elements 102, 102' of Figure 5, in which the number of input/output terminals is reduced. For example, the pairs A and D of terminals for outputting the differential signal from the spin-wave sensors 104 of the devices 102, 102' respectively are combined by corresponding differential to single-ended converters (D2S), and the pairs B and C of terminals for outputting the differential signal from the RF/millimeter wave sensors 108 of the devices 102, 102' respectively are combined by corresponding differential to single-ended converters.

[0083] Figure 7 schematically illustrates a system 700 comprising a probe array 702 and a control board 704. The probe array 702 is for example similar to the probe array 100 of Figure 1, and comprises 64 probing elements 102, 102' arranged in lines and rows. In the example of Figure 7, the array 702 is formed on a support substrate having tongues 706 along at least one side and adapted to engage with corresponding grooves a further support substrate (not illustrated) that can be added to extend the side of the array

[0084] The probe array 702 is coupled to the control board 704 via a wired communications interface 708, although in alternative embodiments a wireless interface could be implemented. The interface 708 for example permits high data rate serial communication between the array 702 and the board 704. [0085] The control board 704 for example comprises at least two analog to digital converters (ADC), and in the example of Figure 7, there are 16 ADCs labelled ADC1 to ADC16. The ADCs are for example configured to convert one or more signals detected by the probing elements of the array. For example, switches are used to sequentially select lines or rows of elements of the array to be sampled, and the 16 ADCs permit an entire row, or an entire line, of probing elements to be read at the same time.

[0086] The control board 704 also for example comprises mixers (MX) for down-converting signals received via the sensors of the array, for example prior to analog to digital conversion. This is for example performed when the frequency of the received signals are in the millimeter wave range of 24.24 GHz or above, or even for relatively high RF frequencies of 5 GHz or above. In some embodiments, there is a mixer for every ADC. Furthermore, in some embodiments, other functions such as amplification by one or more LNAs (Low Noise Amplifier), filtering by one or more filters, etc., may also be performed.

[0087] The control board 704 also for example comprises a processing device, which is for example a field-programmable gate array (FPGA), a memory (MEM), which is for example an SRAM (static random access memory) or a non-volatile memory such as a FLASH memory. The control board 704 also comprises, in some embodiments, one or more digital to analog converters (DAC) configured to generate the DC biasing voltages to be applied to the probing elements of the array 702.

[0088] Figure 8 schematically illustrates a readout circuit 800 for a probe array, in which two channels (CHANNEL A, CHANNEL B) of probing elements are present in a sensor layer (SENSOR LAYER) 806, each channel comprising N probing circuits (Pixel-lxy to Pixel-Nxy). For example, the presence of two channels permits addition information to be gathered. A multiplexing layer (MULTIPLEXING LAYER) 802 for example comprises multiplexers configured to combine the antenna outputs on a reduced number of lines. For example, in one embodiment, for each channel A, B there is one multiplexer (MUX X-POL) for combining the X-polarization signals to a single line, and another multiplexer (MUX Y-POL) for combining the Y-polarization signals to a single line. Each multiplexer for example receives, on separate lines, the outputs from the RF/millimeter wave sensors and the outputs from the spin-wave sensors. The channel A multiplexers are for example controlled by a control signal C-A generated by a control circuit (not illustrated in Figure 8) and the channel B multiplexers are for example controlled by a control signal C-B generated by the same control circuit or another control circuit.

[0089] The output lines of the multiplexers are for example provided to radio frequency integrated circuits (RFIC) 812 for channel A, and 814 for channel B. The RFICs 812, 814 for example form part of a signal conditioning layer (SIGNAL COND. LAYER) of a control board 804, which is for example similar to the board 704 of Figure 7. The signal conditioning layer may additionally comprise further functions, such as down- conversion, low noise amplification, filtering, etc. The output signals from the RFIC 812 provide the measurement signal of channel A (MES. SIGNAL CHANNEL A) and the measurement signal of channel B (MES. SIGNAL CHANNEL B), these signals then being processed by an ADC layer (ADC LAYER) 810.

[0090] While not illustrated in Figure 8, a similar arrangement of multiplexers is for example used in the inverse direction for supplying biasing voltages, for example DC voltages, to the probing elements, these voltages for example being generated by one or more DACs. [0091] While examples have so far been described in which the probing elements of a probing array are coupled via conductive tracks and a serial interface to a control board, it is also possible to provide one or more RF connectors associated with each probing element in order to convey the signals, as will now be described in more detail with reference to Figures 9 to 16.

[0092] Figure 9A is a perspective view of a front side of a spin-wave connection interface 900 comprising connector pads 902 for receiving a connector (not illustrated in Figure 9A). In the example of Figure 9A there are four connector pads 902 that together form an annular band with gaps. The pads 902 are for example formed on a ground plane 904 forming a shielding layer. A conductive track 906 extends from a pad 907, which is positioned centrally with respect to the connector pads 902, to an opening 908 in the ground plane 904. The pad 907 and conductive track 906 are for example insulated from the ground plane 904 by a layer of insulating material.

[0093] Figure 9B is a perspective view of a back side of the spin-wave connection interface 900 of Figure 9A. It can be seen that a via 912 extends through the hole 908 and is connected to a connection pad 914, which is for example formed in an underside of a support substrate (shown as transparent in the figures to aid visibility). Similarly, a connection pad 910 is for example connected to vias that extends from one of the connection pads 902. The connection pads 910 and 916 are for example used to connect to terminals of the spin- wave sensor 104 (not illustrated in Figure 9B).

[0094] Figure 9C is a perspective view of the front side of the spin-wave connection interface of Figure 9A with a connector 918 mounted thereon. The connector 918 for example comprises a substantially cylindrical body, which is for example soldered to the connector pads 902. While not shown in Figure 9C, the connector 918 also for example comprises a central conductor that contacts the central pad 907 (hidden in Figure 9C). In some embodiments, the cylindrical body of the connector 918 comprises slots 920 aligned with the gaps between the connector pads 902 such that the conductive track 906 can pass through with a separation from the body of the connector .

[0095] Figure 9D is a cross-section view of the spin-wave connection interface 900, wherein pillars 922 and 924 represent a dual-pin configuration of the connector.

[0096] Figure 10 is a perspective view of the back side of a spin-wave connection interface 1000, which is similar to the interface of Figure 9, but additionally comprises DC biasing. For example, a conductive track 1002 couples one or more connector pads 1004 on the front side to some vias 1005, which are used to couple the track 1002 to a pad 1006 on the back side. Similarly, a conductive track 1008 couples one or more connector pads 1010 on the front side to some vias 1012, which are used to couple the track 1008 to a pad 1014 on the back side. The pads 914, 916, 1006 and 1014 this provide four connection points to which the connection pads of the spin- wave sensor can be wire-bonded.

[0097] Figure 11 is a perspective view of a front side of a connection interface 1100 for a pair of spin-wave sensors sharing the same DC biasing. The solution is similar to the solution of Figure 10, except that there are two interfaces, one for each sensor, but only one set of connection pads for receiving the DC biasing voltage. A separation s between the central pads 907 of each of the interfaces is for example of between 3 and 10 mm, and for example substantially of 5 mm. [0098] Figure 12A is a perspective view of a front side of a connection interface 1200 for a spin-wave sensor and an RF/millimeter wave sensor according to a further example embodiment .

[0099] The interface for the spin-wave sensor is on the left in Figure 12A, and for example comprises connector pads 1202 that are similar to the connector pads 902 of Figure 9. However, the connector pads 902 are formed on a shielding layer 1204 that is not grounded, but which conveys one part of the differential signal received by the spin-wave sensor. The other part of the differential signal is provided to a pad 1206 positioned centrally with respect to the connector pads 1202, and which is configured to connect to the central conductor of the connector (not illustrated in Figure 12).

[0100] The interface of the RF/millimeter wave sensor is on the right in Figure 12A, and for example comprises connector pads 1208 that are similar to the connector pads, and are formed on a shielding layer 1210 that is not grounded, but which conveys one part of the differential signal received by the RF/millimeter wave sensor. For example, a protrusion 1212 of the layer 1210 is coupled by vias 1214 to a connection pad 1216 formed on the back side of a support substrate (transparent in Figure 12). The other part of the differential signal from the RF/millimeter wave sensor is provided to a pad 1218 positioned centrally with respect to the connector pads 1208, and which is configured to connect to the central conductor of the connector (not illustrated in Figure 12).

[0101] A separation s between the central pads 1206, 1218 of each of the interfaces is for example of between 3 and 8 mm, and for example substantially of 4 mm.

[0102] Figure 12B is perspective view of a back side of the connection interface of Figure 12A. [0103] A via 1220 for example couples the shielding layer

1204 to a connection pad 1222 formed on the back side, and a via 1224 for example couples the pad 1206 to a connection pad 1226 formed on the back side. The pads 1222, 1226 are for example used to connect corresponding antennas of a dipole antenna .

[0104] A via 1228 for example couples the pad 1218 to a connection pad 1230 formed on the back side. The pads 1216 and 1230 are for example used to connection corresponding contacts of the spin-wave sensor.

[0105] Figure 13A is a perspective view of the front side of a spin-wave connection interface 1300, which is similar to the interface of Figure 12A and 12B, but additionally comprises DC biasing. For example, a conductive track 1302 couples one or more connector pads 1304 on the front side to some vias 1305, which are used to couple the track 1302 to a pad 1306 on the back side. Similarly, a conductive track 1308 couples one or more connector pads 1310 on the front side to some vias 1312, which are used to couple the track 1308 to a pad 1314 on the back side. The pads 314, 1212, 1306 and 1314 this provide four connection points to which the connection pads of the spin-wave sensor can be wire-bonded.

[0106] Figure 13B is a perspective view of a back side of the connection interface 1300 of Figure 13A.

[0107] Figure 14A is a perspective view of a connection interface 1400 for a pair of spin-wave sensors with DC biasing according to a further example embodiment. In the example of Figure 14A, there are two connectors 1402, 1404 used for outputting signals from the spin-wave sensors, these connectors 1402, 1404 for example being SMPM (Sub-Miniature

Push-on Micro) connectors. There are a further two connectors 1406, 1408 for receiving the DC biasing voltages for biasing the respective spin-wave sensors. In the example of Figure 14A, the connectors are arranged in a linear fashion with the connectors 1402 and 1404 next to each other, and the connectors 1406 and 1408 positioned respectively alongside the connectors 1402 and 1404.

[0108] Figure 14B is an underside view of the connection interface 1400 of Figure 14A. Spin-wave sensors 1410 and 1412 are respectively positioned under the connectors 1402, 1404, for example adjacent to each other. The DC biasing contacts of the sensor 1410 are connected by wire-bonding to metal tracks from the connector 1406, and similarly the DC biasing contacts of the sensor 1412 are connected by wire-bonding to metal tracks from the connector 1408. One of the output contacts of the sensor 1410 is connected via wire-bonding to a connection pad connected to a central conductor of the connector 1402, and the other output contact of the sensor 1410 is connected via wire-bonding to a shielding layer 1414 on the underside of the connector 1402. Similarly, one of the output contacts of the sensor 1412 is connected via wire bonding to a connection pad connected to a central conductor of the connector 1404, and the other output contact of the sensor 1412 is connected via wire-bonding to a shielding layer 1416 on the underside of the connector 1404.

[0109] Figure 15A is a perspective view of a connection interface 1500 for a pair of spin-wave sensors with DC biasing, a pair of RF/millimeter wave sensors, and a pair of loop sensors according to a further example embodiment. The connection interface 1500 is similar to the connection interface 1400 of Figure 14, but additionally comprises, between the connectors 1402 and 1406, a further SMPM connector 1502 for coupling a loop sensor, between the connectors 1404 and 1408 a further SMPM connector 1504 for coupling a further loop sensor, and further SMPM connectors 1506 and 1508 for coupling respective dipole antennas.

[0110] Figure 15B is an underside view of the connection interface 1500 of Figure 15A. A dipole antenna 1510 is visible on the underside of the connector 1506, and a dipole antenna 1512 is visible on the underside of the connector 1508. A loop 1514 of one loop sensor is visible on the underside of the connector 1502, and a loop 1516 of the other loop sensor is visible on the underside of the connector 1504. The connectors 1402, 1502, 1406 and 1506, and the spin-wave sensor 1410, dipole antenna 1510 and loop sensor 1514, together for example form a first probing element and its connection interface, while connectors 1404, 1504, 1408 and 1508, and the spin-wave sensor 1412, dipole antenna 1512 and loop sensor 1516, together for example form a second probing element and its connection interface.

[0111] Figure 16 is a perspective view of a test chamber 1600 according to an example embodiment of the present disclosure. The test chamber is for example substantially cuboid, comprises six walls, including top and bottom walls 1602, 1604, left and right walls 1606, 1608, and front and back walls 1610, 1612. The walls are shown as transparent in Figure 16 to aid illustration, but each of the walls for example incorporates a respective probe array as described herein. A device under test (DUT) is positioned inside the chamber 1600. In some embodiments, a thermal camera 1614, and/or a visible light camera 1616, are also positioned with the chamber 1600.

[0112] The test chamber for example has width, depth and height dimensions of between 3 and 30 cm.

[0113] Figure 17 schematically represents a test system 1700 comprising the test chamber 1600 of Figure 16, the probe arrays 1702, 1704, 1706 and 1708 positioned on the top, bottom, left and right walls being represented in Figure 17 (the probe arrays on the front and back walls are omitted for each of illustration) . Each of the probe arrays 1702, 1706, 1706 and 1708 for example comprises an array of 16 by 16 probing elements, although different array sizes would be possible.

[0114] The test system 1700 provides a nonlinear smart sensing solution, and for example comprises:

- A non-intrusive NV-Quantum sensor array combined with spintronic nanothermometry, integrated into one or more walls of the test chamber. NV-Quantum sensing is for example described in more detail in the publication entitled "Design and Application of a Near Field Microwave Antenna for Spin Control of Nitroget-Vacancy Centers", Yang Li-Li et al., CHIN. PHYS. LETT., Vol. 27, No.3 (2010) 038401, in the publication by Christopher L. Holloway entitled "Broadband Rydberg Atom-Based Electric-Field Probe: From Self-Calibrated Measurements to Sub-Wavelength Imaging" arXiv:1405.7066vl [physics.atom-ph] 27 May 2014, and in the publication by Bo Yang et al., entitled Non-Invasive Imaging Method of Microwave Near Field Based on Solid State Quantum Sensing", arXiv:1801.01706vl [physics.ins-det] 5

Jan 2018, the contents of these three publications being hereby incorporated by reference.

- The probe arrays 1702 to 1708: composed of Spin-wave/Hall sensors array with autonomous biasing and control. Hybridization of Spin-wave/Hall sensors with meta- surface/meta-material structures is fully supported both for Magnetic and Electric fields.

- Thermal camera 1614 for the extraction of heat maps.

- Visual camera 1616 for the extraction of DUT layout and features. - A Smart Built-in-Self-Test (SBIST) 1714 based Nonlinear sensing and calibration with multi-level signal processing. The multi-level signal processing for example includes both full-array, sub-array, co-array and mosaic-based partitioning algorithms and solutions.

[0115] As represented by arrows 1710, 1712, the separation distance between the DUT and the top and bottom walls of the chamber is for example adjustable.

[0116] A circuit 1716 is for example coupled to the SBIST 1714 and is composed of signal generators, signal analyser, DC-RF correlators and high-speed PC-driven signal processing units .

[0117] A platform 1718 is for example coupled to the circuit 1716 and is composed of seamless bridging to interoperable EDA tooling platforms with loop back to design, optimization and verification. This bridging operates unified instrumentation and EDA solutions.

[0118] Figure 18 illustrates a probe array comprising patch antennas according to an example embodiment of the present disclosure. Indeed, while embodiments are described above in which an antenna for RF/millimeter wave sensing is for example implemented by a dipole antenna, in alternative embodiments one or more patch antennas could be used. In some embodiments, such a patch antenna may permit DC biasing via biasing control lines in addition to the standard antenna feed. This the DC biasing voltage that is applied to the spin-wave sensor of each probing element, or a further DC biasing voltage, may be applied to these control lines.

[0119] Figure 19 is a graph illustrating non-linear DC-RF Correlation for EM-field based programmable arrays using hybrid RF/millimeter-wave and spin-wave sensors. In particular, a graph on the right in the figure represents an example of a DC biasing voltage, which in some embodiments have an oscillating component at relatively low frequency. A graph at the bottom of the figure represents the magnetic field .

[0120] Various embodiments and variants have been described. Those skilled in the art will understand that certain features of these embodiments can be combined and other variants will readily occur to those skilled in the art.

[0121] Finally, the practical implementation of the embodiments and variants described herein is within the capabilities of those skilled in the art based on the functional description provided hereinabove.

Claims

1.A probing device comprising: at least two probing elements (102, 102'), each probing element comprising a spin-wave sensor (104, 1410, 1412) mounted on a support substrate (312), each spin-wave sensor comprising at least four connection terminals (302, 304,

306, 308) electrically coupled to connection pads (314, 914, 916, 1006, 1014, 1216, 1230, 1224, 1314, 1414, 1416) on the support substrate.

2. The probing device of claim 1, wherein each probing element

(102, 102') is a hybrid sensor further comprising an antenna (108) forming an RF/millimeter-wave sensor.

3. The probing device of claim 2, wherein the antenna (108) has at least first and second connection terminals, and wherein the first connection terminal of the antenna (108) is electrically connected to a first of the at least four connection terminals of the spin-wave sensor (104, 1410,

1412), and the second connection terminal of the antenna (108) is electrically connected to a second of the at least four connection terminals of the spin-wave sensor.

4. The probing device of any of claims 1 to 3, wherein the spin-wave sensors (104, 1410, 1412) of first and second ones of the probing elements (102, 102') are orientated to receive signals of opposite polarizations to each other.

5. The probing device of claim 4 when dependent on claim 2 or 3, wherein the antenna (108) of each probing element (102, 102') is a dipole antenna, the dipole antennas of the first and second probing elements being orientated to receive signals of opposite polarizations to each other.

6. The probing device of any of claims 1 to 5, wherein two of the at least four connection pads are coupled to biasing rails (1002, 1008, 1302, 1308) configured to receive biasing voltages, which are for example DC (Direct Current) biasing voltages.

7. The probing device of any of claims 1 to 6, wherein the support substrate (312) comprises a shielding layer (316, 904, 1204, 1210, 1414, 1416) formed of a metal, and wherein each pad is coupled to a via passing through an opening in the shielding layer.

8. The probing device of any of claims 1 to 7, wherein the probing elements form an array (100) of at least four rows and at least four lines.

9. The probing device of any of claims 1 to 8, wherein each probing element (102, 102') further comprises at least one connector (918, 1402, 1404) mounted on the support substrate (312), the connector comprising an outer cylindrical conductive portion coupled, for example, to a ground rail, and a central conductive portion surrounded by and insulated from the outer cylindrical portion and configured to receive at least one signal received by the probing element.

10. A test system comprising: the probing device of any of claims 1 to 9; and a control board (704) coupled to the probing device, the control board comprising at least one digital to analog converter (DAC) configured to generate a voltage signal for biasing one or more of the spin-wave sensors (104, 1410,

1412).

11. The test system of claim 10, wherein the control board further comprises: - at least two mixers (MX) configured to down-convert the frequencies of signals received by one or more of the probing devices into digital signals; and

- at least two analog to digital converters (ADC1-ADC16) configured to convert the down-converted signals into digital signals.

12. The test system of claim 11, further comprising one or more multiplexers (802) configured to route the signals received by the one or more probing devices to the at least two analog to digital converters.

13. A test chamber comprising at least four walls (1602— 1612) defining a volume for the placement of a device under test (DUT), each wall comprising the probe array of claim 8 configured to receive emissions from the device under test.

14. The test chamber of claim 13, further comprising:

- at least one thermal camera (1614) configured to capture thermal images of the device under test (DUT); and/or

- at least one visible-light camera (1616) configured to capture images of the device under test.