A waveguide transition arrangement
The waveguide transition arrangement addresses manufacturing challenges by using a compact planar structure with low-loss signal coupling, achieving efficient RF performance and cost-effectiveness for frequencies up to 300 GHz.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
- Filing Date
- 2024-12-18
- Publication Date
- 2026-06-25
AI Technical Summary
Existing waveguide transitions for frequencies above 100 GHz face challenges in manufacturing reliability and cost-efficiency due to increased losses, parasitic inductances, and mechanical scaling difficulties, particularly for D-band and beyond, with current solutions being too expensive for volume production.
A waveguide transition arrangement comprising an electrically conductive backshort, dielectric carrier materials, and metallization layers with a trench and waveguide aperture, allowing for low-loss signal coupling between a transmission line and waveguide, using a compact planar structure compatible with PCB technology.
Supports wide bandwidth with low losses up to 300 GHz while maintaining low production costs, enabling excellent RF performance and compatibility with standard printed circuit boards.
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Figure SE2024051104_25062026_PF_FP_ABST
Abstract
Description
[0001] TITLE
[0002] A waveguide transition arrangement
[0003] TECHNICAL FIELD
[0004] The present disclosure relates to a waveguide transition arrangement for coupling a signal between a transmission line and a waveguide aperture.
[0005] BACKGROUND
[0006] In many fields of wireless communication, as well as for applications associated with radars and other sensors, waveguides are used for transporting wireless signals, due to the low losses incurred in a waveguide.
[0007] In many applications, radios use waveguides as interface to antennas and / or diplexer filters. Therefore, it is common to use a planar transmission line (such as coplanar or microstrip) to waveguide transition in the design since integrated circuits (ICs), such as RFICs (radio frequency ICs), and printed circuit boards (PCBs) often use planar transmission lines.
[0008] A waveguide transition is normally designed around a PCB that comprises a waveguide aperture and a shorted waveguide part, a so called backshort, on one side. The waveguide aperture continues to the next radio frequency (RF) component in waveguide technology, for example a continuing waveguide or a diplexer filter, and the backshort continues a relatively short distance, e.g. a quarter wavelength, before it is short circuited, and is used for reflecting the wave back through the waveguide aperture. The waveguide aperture is provided with a probe that is adapted to radiate and is connected to a planar transmission line. A typical such waveguide transition is described in "Wideband Probe-Type Waveguide-to-Microstrip Transition for V-band Applications” by Oleg Soykin, Alexey Artemenko, Vladimir Ssorin, Andrey Mozharovskiy and Roman Maslennikov, Radio Gigabit LLC, Nizhny Novgorod, Russia (Proceedings of the 46th European Microwave Conference).
[0009] At D-band, which is 130 GHz to 174.8 GHz for wireless communications networks, and frequencies beyond, a waveguide transition becomes difficult to manufacture in a reliable and cost-efficient manner. To transfer a signal from an RFIC die to a waveguide interface, a chip-to-waveguide transition is required and should have a low insertion loss over a wide bandwidth while being possible to fabricate it at a reasonable cost.
[0010] This is due to the fact that for frequencies above 100 GHz this becomes increasingly complicated due to increased losses, parasitic inductances, and difficulties to scale mechanical dimensions and tolerances in the same scale as the wavelength. For D-band frequencies and beyond, there exists no commercial packages with a waveguide port except for very high-end products manufactured in small series for research use.
[0011] At sub-millimeter wave and up to several THz, air-suspended membrane technology has been used to achieve transmission lines and waveguide probes, typically an E-plane probe, with very low loss. The circuit is realized on a thin substrate which is suspended in an air channel effectively creating a planar transmission line with very low dielectric loss and a waveguide probe with almost no dielectric substrate disturbing the E-field. The membrane circuit is provided mechanical support and electrical grounding with so called beamleads. A beamlead comprises an area of conductive metal where, under a portion of the area, the substrate has been entirely removed. The membrane circuits are typically encapsuled in a split-block module, a housing formed by two pieces of electrically conductive material, normally two halves, where the beamleads are clamped between the two halves. The waveguide probe is configured to couple a signal between the transmission line and a waveguide. The waveguide is formed by the two halves and has an extension direction in the same direction as a plane of the air-suspended membrane. This is described in “InP DHBT Amplifier Modules Operating Between 150-300 GHz Using Membrane Technology” by Kias Eriksson, Peter J. Sobis, Sten E. Gunnarsson, Johanna Hanning, and Herbert Zirath (IEEE Transactions on Microwave Theory and Techniques), Vol. 63, No. 2, February 2015. Here the beamleads are used as a low-inductance RFIC connection from the membrane substrate to the RFIC. Three beamleads forming a ground-signal-ground (GSG) connection, essentially a coplanar- waveguide, are connected to the GSG pads on the RFIC. This is, however, an example of a high-end product manufactured for research use, and is therefore very expensive to manufacture and consequently not suitable for volume production.
[0012] There is thus a need for an improved waveguide transition arrangement adapted for electrically connecting a waveguide interface to a signal conductor, where the above drawbacks are minimized. In particular, for the case where the signal conductor is connected to an RFIC.
[0013] SUMMARY
[0014] It is an object of the present disclosure to provide an improved waveguide transition arrangement adapted for electrically connecting a waveguide interface to a signal conductor where the above drawbacks are minimized.
[0015] Said object is obtained by means of a waveguide transition arrangement for coupling a signal between a transmission line and a waveguide aperture. The transition arrangement comprises an electrically conductive backshort, a first layer structure comprising a first dielectric carrier material and a first metallization layer, and a second layer structure. The second layer structure comprises a second dielectric carrier material, a second metallization layer, a trench provided with electrically conductive trench walls, and a waveguide aperture that is connected to the trench. The waveguide aperture comprises electrically conductive inner waveguide walls and defines a waveguide that has a signal propagation extension into the second layer structure.
[0016] The first metallization layer comprises a probe, a first signal conductor, and a pair of beamlead conductors that are formed on each side of the first signal conductor. The first signal conductor is comprised in the transmission line, and an end of the first signal conductor is connected to the probe. The second metallization layer comprises trench side conductors that are formed on opposite sides along the trench, and an aperture conductor that partially circumvents the waveguide aperture. The first layer structure is arranged relative the second layer structure such that the respective beamlead conductors are connected to the respective trench side conductors, such that the first layer structure at least partly closes the trench, such that the first signal conductor runs along to the trench, and such that the probe is configured to couple the signal between the transmission line and a waveguide mode into or from the waveguide aperture. Furthermore, the backshort is connected to the aperture conductor.
[0017] This way, there is provided a waveguide transition arrangement that supports a relatively wide bandwidth and presents relatively low losses at frequencies above 100 GHz. At the same time the production cost is kept at a low level, while enabling a small size and compatibility with standard printed circuit board (PCB) technology. It is thereby possible to combine an excellent RF performance with a relatively low production cost for the full D-band spectrum and for frequencies beyond 200 GHz up to at least 300 GHz.
[0018] According to some aspects, the trench walls comprise first vias and an electrically conductive layer that is comprised in the second layer structure, the first vias being connected to the electrically conductive layer. According to some further aspects, the trench walls comprise a trench wall metallization that is formed in the trench. Clearly, many possibilities exist for forming the trench and its walls.
[0019] According to some aspects, each of the first and the second dielectric carrier materials is made in an organic or ceramic material, and where the thickness of the first dielectric carrier material falls below 0,1 A, and more preferably falls below 0,05A, where A is a wavelength that corresponds to a center frequency in a frequency band of operation. Having a relatively thin first dielectric carrier material, transmission losses can be kept very low, and also enables the probe to have a wideband functionality with low losses.
[0020] According to some aspects, the backshort comprises a backshort aperture through which the first signal conductor passes into an interior cavity of the backshort from outside the interior cavity such that the first signal conductor and the probe extends across a part of the waveguide aperture. This means that the backshort has an opening where the air-suspended first signal conductor enters the waveguide aperture inside the backshort without being short-circuited to a ground potential.
[0021] According to some aspects, the first dielectric carrier material only extends until the trench connects to the waveguide aperture. The partial absence of the first dielectric carrier material further reduces losses.
[0022] According to some aspects, the backshort aperture has an inner width Wb that presents a cut-off frequency for higher waveguide modes relative to a frequency band of operation of the waveguide transition arrangement. According to some further aspects, the trench has an inner trench width wtthat presents a cut-off frequency for higher waveguide modes relative to a frequency band of operation of the waveguide transition arrangement. This means that undesired waveguide modes do not propagate via the backshort aperture or in the trench.
[0023] According to some aspects, the backshort aperture is aligned with the trench. This way lateral misalignment that can cause a discontinuity in the waveguide that is formed by the waveguide aperture can be avoided. According to some aspects, the waveguide transition arrangement is adapted for a center frequency in a frequency band of operation that at least partly lies within 130GHz-174.8GHz and / or higher frequency bands. This means that the waveguide transition arrangement is suitable for these frequency bands, which today present a challenge using existing technology.
[0024] According to some aspects, the first metallization layer comprises a second signal conductor, wherein the first and the second signal conductors are positioned between the beamlead conductors and are comprised in the transmission line, and wherein a corresponding probe is connected to the first and the second signal conductors. In this way an alternative waveguide transition arrangement is provided. Furthermore, the corresponding probe may be a dipole probe.
[0025] According to some aspects, the waveguide aperture defines a waveguide that has a signal propagation extension perpendicular to a plane that runs through the second metallization layer. This means that a waveguide transition arrangement is provided where the waveguide runs perpendicular to the layer structures, which has never been disclosed before for waveguide transition arrangements as described herein.
[0026] According to some further aspects, the transmission line is a planar transmission line. According to some aspects, the first metallization layer and the second metallization layer are mutually parallel. This enables a compact planar structure to be formed.
[0027] This object is also obtained by means of radio unit components and radio units that are associated with the above advantages.
[0028] BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The present disclosure will now be described more in detail with reference to the appended drawings, where:
[0030] Figure 1 shows a schematic top view of a first layer structure and a second layer structure according to a first example;
[0031] Figure 2A shows a first section view of Figure 1 ;
[0032] Figure 2B shows a second section view of Figure 1 ;
[0033] Figure 3 shows a schematic top view of a first layer structure and a second layer structure according to a second example;
[0034] Figure 4A shows a first section view of Figure 3; Figure 4B shows a second section view of Figure 3;
[0035] Figure 5 shows the view of Figure 4B for a complete waveguide transition arrangement;
[0036] Figure 6 shows a longitudinal section of the view in Figure 5;
[0037] Figure 7 shows a schematic top perspective view of the waveguide transition arrangement;
[0038] Figure 8 shows a schematic exploded top perspective view of the waveguide transition arrangement prepared for system-in-package;
[0039] Figure 9 shows a schematic bottom perspective view of an electrically conductive backshort and a housing part;
[0040] Figure 10 shows a schematic view of a radio unit; and
[0041] Figure 11 shows a schematic top view of a main layer structure according to a third example.
[0042] DETAILED DESCRIPTION
[0043] Aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings. The different devices, systems, computer programs and methods disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the aspects set forth herein. Like numbers in the drawings refer to like elements throughout.
[0044] The terminology used herein is for describing aspects of the disclosure only and is not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
[0045] With reference to Figure 1 , Figure 2A and Figure 2B, there is a first layer structure 103 and a second layer structure 106 according to a first example. With reference to Figure 3, Figure 4A and Figure 4B, there is a first layer structure 103 and a second layer structure 306 according to a second example. With refence to Figure 5-7 there is waveguide transition arrangement 300, 700 that comprises the first layer structure 103 and the second layer structure 106, 306.
[0046] With reference to Figure 1-7, there is a waveguide transition arrangement 300, 700 for coupling a signal between a transmission line 120, 320 and a waveguide aperture 112, 312, 712. Since Figure 1-6 illustrate the first example and the second example, both examples will generally be described together in the following, while the differences between the first example and the second example will be discussed separately. Figure 7 shows a more general view of a waveguide transition arrangement 700 that may cover both examples disclosed as well as other possible embodiments of the waveguide transition arrangement.
[0047] The waveguide transition arrangement 300 comprises an electrically conductive backshort 319, 719, a first layer structure 103, 703 comprising a first dielectric carrier material 104 and a first metallization layer 105, and a second layer structure 106, 306, 706 comprising a second dielectric carrier material 107, 307, a second metallization layer 108, 308, a trench 109, 309, 709 provided with electrically conductive trench walls 110, 111 ; 318, and a waveguide aperture 112, 312, 712 that is connected to the trench 109, 309, 709. The waveguide aperture 112, 312, 712 comprises electrically conductive inner waveguide walls 321 and defines a waveguide that has a signal propagation extension E into the second layer structure 106, 306, 706.
[0048] According to some aspects, according to the first example and as illustrated in Figure 1 , Figure 2A and Figure 2B the trench walls 110, 111 comprise first vias 110 and an electrically conductive layer 111 that is comprised in the second layer structure 106, 306, 706, the first vias 110 being connected to the electrically conductive layer 111.
[0049] According to some aspects, according to the second example and as illustrated in Figure 3, Figure 4A and Figure 4B, the trench walls 318 comprise a trench wall metallization 318 that is formed in the trench 309. As shown in Figure 4A and Figure 4B the trench wall metallization 318 is a coherent metallization that forms the three walls of the trench 309. The trench need not have three distinct walls, but may have an alternative shape, for example a rounded U-shape.
[0050] A difference between the first example and the second example is thus that in the first example first vias 1 10 and an electrically conductive layer 111 , such as a metal layer, are used to define the trench walls, and in the second example a metallization layer forms the trench walls.
[0051] According to some aspects, the first metallization layer 105 and the second metallization layer 108, 308 are mutually parallel. This enables a compact planar structure to be formed.
[0052] Furthermore, the first metallization layer 105 comprises a probe 116, a first signal conductor 113 and a pair of beamlead conductors 114A, 114B that are formed on each side of the first signal conductor 113.
[0053] Beamlead conductors are previously well-known, here the beamlead conductors 114A, 114B extend along the trench and are formed in the first metallization layer 105, where a part of the first dielectric carrier material 104 has been entirely removed along the extension of the beamlead conductors 114A, 114B. This means that along the beamlead conductors 114A, 114B there is an area where only the metal part is left, extending out from the first metallization layer 105. There should of course be enough left of the first dielectric carrier material 104 to enable the beamlead conductors 114A, 114B to stay attached to the first metallization layer 105. The first signal conductor 113, 113A is comprised in the transmission line 120, 320, and an end of the first signal conductor 113 is connected to the probe 116. The second metallization layer 108, 308 comprises trench side conductors 115A, 115B; 315A, 315B that are formed on opposite sides along the trench 109, 309, 709, and an aperture conductor 117, 317 that partially circumvents the waveguide aperture 112, 312, 712.
[0054] According to some aspects, the first signal conductor 113, 113A, together with the beamlead conductors 114A, 114B and / or the trench walls 110, 111 ; 318 are comprised in the transmission line 120, 320. According to some further aspects, the transmission line 120, 320 is a planar transmission line. For example, the first signal conductor 113, 113A, together with the beamlead conductors 114A, 114B may be configured as a coplanar waveguide.
[0055] Suitably, and according to some aspects, the trench side conductors 115A, 115B; 315A, 315B and the aperture conductor 117, 317 are formed in the second metallization layer 108, 308, and may together form a coherent conductor. The trench side conductors 115A, 115B; 315A, 315B and the aperture conductor 117, 317 are thus ordinary conductors that have certain positions and limitations, the trench side conductors 115A, 115B; 315A, 315B being positioned on opposite sides of the trench 109, 309, and the aperture conductor 117, 317 partly circumventing the waveguide aperture 112, 312, 712 and providing a contact surface for the backshort 319.
[0056] According to some aspects, in the first example, the trench side conductors 115A, 115B are electrically connected to the first vias 110 that together with the electrically conductive layer 111 form the trench walls. Also, in the first example, second vias 121 are arranged along the aperture conductor 117, connecting the aperture conductor 117 to the electrically conductive layer 111.
[0057] Furthermore, in accordance with the present disclosure, the first layer structure 103, 703 is arranged relative the second layer structure 106, 306, 706 such that the respective beamlead conductors 114A, 114B are connected to the respective trench side conductors 115A, 1 15B; 315A, 315B. In this manner, the first layer structure 103, 703 at least partly closes the trench 109, 309, 709, the first signal conductor 113, 113A runs along to the trench 109, 309, 709, and the probe 116, 116A is configured to couple the signal between the transmission line and a waveguide mode into or from the waveguide aperture 112, 312, 712. Furthermore, the backshort 319, 719 is connected to the aperture conductor 117, 317.
[0058] Figure 2A and Figure 4A show corresponding section views where the first layer structure 103 is positioned above the second layer structure 106, 306, and Figure 2B and Figure 4B show corresponding section views where the first layer structure 103 has been positioned on the second layer structure 106, 306 and the respective beamlead conductors 114A, 114B are connected to the respective trench side conductors 115A, 115B; 315A, 315B.
[0059] It is to be noted that Figure 5 and Figure 6 show section views of Figure 3 where the backshort 319 is present, while the backshort is not shown in Figure 3 for reasons of clarity. According to some aspects, the probe 116 is configured to couple the signal between the transmission line 120, 320 and a first order Transverse Electric, TE01 , mode into or from the waveguide aperture 112, 312. In this configuration, the probe 116 may be called an E-plane probe.
[0060] Also, although not explicitly shown, a backshort such as the one shown in Figure 5 and Figure 6 can of course be mounted to the layer structures 103, 106 in the first example illustrated in Figure 1 , Figure 2A and Figure 2B such that a complete waveguide transition arrangement according to the first example is formed.
[0061] By means of the present disclosure, there is provided a waveguide transition arrangement 300 that supports a relatively wide bandwidth and presents relatively low losses at frequencies above 100 GHz. At the same time the production cost is kept at a low level, while enabling a small size and compatibility with standard printed circuit board (PCB) technology. The expensive mechanics in prior art designs are here replaced with a low-cost planar carrier board, e.g. a PCB or a thin-film board, as the second layer structure 106. It is thereby possible to combine an excellent RF performance with a relatively low production cost for the full D-band spectrum and for frequencies beyond 200 GHz up to at least 300 GHz. Possible applications are wireless radio, instrumentation and imaging.
[0062] It should be understood that many other structures are possible for the waveguide transition arrangement, for example the first vias 110 may be connected to a metallization formed on a dielectric carrier material instead of the electrically conductive layer 111. Also, one of the trench walls may be formed by an electrically conductive layer 111 as in the first example while the other walls are formed by trench wall metallizations as in the second example. For example, if the depth of the trench 109 extends all the way through the second dielectric carrier material 107, the surface underneath is preferably electrically conductive as in the first example. According to some aspects, the bottom of the trench 109 may be a metallization layer sandwiched inside the second layer structure 106 that then is constituted by a multilayer PCB. If the depth of the trench 309 does not extend all the way through the second dielectric carrier material 307, the bottom surface is preferably metallized as in the second example.
[0063] Clearly, many possibilities exist for forming the trench 109, 309 and its walls 110, 111 ; 318.
[0064] According to some aspects, the waveguide aperture 112, 312, 712 defines a waveguide that has a signal propagation extension E perpendicular to a plane P that runs through the second metallization layer 108, 308 as illustrated in Figure 6. This means that a waveguide transition arrangement 300 is provided where the waveguide runs perpendicular to the layer structures 103, 106; 306, which has never been disclosed before for an air-suspended circuit in the form of the first layer structure 103 that is placed over the trench 109, 309, closing it, as described above.
[0065] As mentioned, the probe 116, 116A is configured to couple the signal between the transmission line and a waveguide mode into or from the waveguide aperture 112, 312, 712. At the other opening of the waveguide defined by the waveguide aperture (e.g., the bottom of the waveguide aperture 312 in Figure 6), an external waveguide may be attached. The backshort 319 preferably has an electrically conductive connection with the metalized waveguide aperture 112, 312 to reassure an unbroken waveguide connection. This electrically conductive connection, here between the backshort 319 and the aperture conductor 317, can for example be realized with e.g. conductive adhesive or solder. If the backshort 319 is partly placed on top of the beamlead conductors 114A, 114B, this seam or contact interface should be adapted for the height differences that are incurred. The positioning of the waveguide backshort 319 is important as a lateral misalignment will cause a discontinuity in the waveguide that is formed by the waveguide aperture 312.
[0066] This means that an air-suspended circuit in the form of the first layer structure 103, is placed over the trench 109, 309, closing it, where sufficient mechanical support is provided by the beamlead conductors 114A, 114B which are attached to the trench side conductors 115A, 115B; 315A, 315B with e.g. ultrasonic clamping with a bonding machine tool head and / or conductive adhesive.
[0067] According to some aspects, the first dielectric carrier material 104 forms a very thin membrane. According to some aspects, each of the first and the second dielectric carrier materials 104, 107; 307 is made in an organic or ceramic material, and where the thickness t of the first dielectric carrier material 104 falls below 0,1 A, and more preferably falls below 0,05A, where A is a wavelength that corresponds to a center frequency in a frequency band of operation. Having a relatively thin first dielectric carrier material 104, transmission losses can be kept very low, and also enables the probe 116 to have a wideband functionality with low losses.
[0068] Generally, the material of the dielectric carrier materials 104, 107; 307 can be organic, ceramic, or metal, as long as the surfaces can be partly or fully metallized where needed. It should be noted that a carrier board in an organic or ceramic dielectric material has the benefit of allowing planar conducting lines for e.g. direct current (DC) supply or intermediate frequency (IF) signals which for example may be needed for electronic components. Potential heat management of such components can then be solved in traditional way with a via farm or a metal coin if necessary. A radio unit component comprising the waveguide transition arrangement as described herein and an integrated circuit will be described later. The use of metal as carrier board material allows other machining methods than for organic and ceramic materials, e.g. milling and Electrical Discharge Machining (EDM), which might be beneficial from a cost or precision perspective.
[0069] According to some aspects, the backshort 319 comprises a backshort aperture 322 through which the first signal conductor 113, 113A passes into an interior cavity 323 of the backshort 319, 719 from outside the interior cavity 323 such that the first signal conductor 113 and the probe 116 extends across a part of the waveguide aperture 112, 312. According to some further aspects, the backshort aperture 322 has an inner width Wb that presents a cut-off frequency for higher waveguide modes relative to a frequency band of operation of the waveguide transition arrangement. This means that undesired waveguide modes do not propagate via the backshort aperture 322. The backshort aperture 322 also has an inner height hb. In other words, the backshort 319 thus has an opening 322 where the air-suspended first signal conductor 113 enters the waveguide aperture inside the backshort 319, the first signal conductor 113 would otherwise be short-circuited to a ground potential. The dimensions of the backshort aperture 322 should be small enough such that the cut-off frequency for a waveguide mode lies above the frequency band of operation.
[0070] It should be noted that in the present example, the backshort 319 is adapted to be connected to a ground potential, and is connected to the aperture conductor 117, 317, the electrically conductive inner waveguide walls 321 , the trench walls 110, 111 ; 318 and the beamlead conductors 114A, 114B, which consequently also are adapted to be connected to a ground potential. It should be noted that other alternatives exist, these parts not necessarily having to be adapted to be connected to a ground potential.
[0071] Similarly, according to some aspects, the trench 109, 309 has an inner trench width Wtthat presents a cut-off frequency for higher waveguide modes relative to a frequency band of operation of the waveguide transition arrangement. The inner trench width wtshould thus be chosen such that the cut-off frequency lies above the frequency band of operation. If a dielectric material is used for the carrier, RF radiation into the carrier dielectric should be prevented as well, for example by means of mode-suppressing vias. This means that undesired waveguide modes do not propagate in the trench 109, 309. The trench 109, 309 also has an inner height ht.
[0072] According to some aspects, the backshort aperture 322 together with the trench 309 forms an interface waveguide, with an extension direction along the longitudinal extension of the trench 309, formed at the overlap between the backshort aperture 322 and the trench 309. A part of the first layer structure 103 is sandwiched in the interface waveguide. The inner widths wt>, wtof the backshort aperture 322 and the trench 309 are preferably selected such that the interface waveguide presents a cut-off frequency for higher waveguide modes relative to a frequency band of operation of the waveguide transition arrangement 300. In the above, the term "interface” in "interface waveguide” is to be regarded as arbitrary nomenclature.
[0073] According to some aspects, the backshort aperture 322 is aligned with the trench 109, 309. This way lateral misalignment that can cause a discontinuity in the waveguide that is formed by the waveguide aperture 312 can be avoided.
[0074] The first dielectric carrier material 104 provides mechanical support for the first signal conductor 113 and the probe 116. If the mechanical strength of the conductor metal is sufficient, the first dielectric carrier material 104 can optionally be removed such that it does not extend into the waveguide aperture 112, 312. This will completely remove the dielectric losses of the probe 116 as only the metallization remains, i.e., the probe 116 is effectively a beamlead.
[0075] In other words, according to some aspects, the first dielectric carrier material 104 only extends until the trench 109, 309 connects to the waveguide aperture 112, 312. This means that the first layer structure 103 mostly comprises only the first metallization layer 105 in the waveguide aperture 112, 312, i.e., the first signal conductor 113 and the probe 116 extend in the waveguide aperture 112, 312 at least mainly without support from the first dielectric carrier material 104 directly at the area of the probe. The partial absence of the first dielectric carrier material 104 further reduces losses.
[0076] According to some aspects, the waveguide transition arrangement 300 is adapted for a center frequency in a frequency band of operation that at least partly lies within the D-band, 130GHz-174.8GHz and / or higher frequency bands. This means that the waveguide transition arrangement 300 is suitable for these frequency bands, which today presents a challenge using existing technology.
[0077] An alternative waveguide transition arrangement 10T is shown in Figure 11. This waveguide transition arrangement utilizes differential signal conductors 113A, 113B and the beamlead conductors 114A , 114B, and a dipole probe 116A, 116B is used to couple to the waveguide aperture 112. This means that, according to some aspects, the first metallization layer 105 comprises a second signal conductor 1 13B, where the first and the second signal conductors 113A, 113B are positioned between the beamlead conductors 114A, 114B and are comprised in the transmission line, and wherein a corresponding probe 116A, 116B is connected to the first and the second signal conductors 113A, 113B. Here, the where the probe is a dipole probe that is a two-part probe with respective parts 116A, 116B connected to the first and the second signal conductors 113A, 113B, respectively. In this way an alternative waveguide transition arrangement 10T is provided.
[0078] Although the alternative waveguide transition arrangement 101' is described for a configuration according to the first example above, it is of course applicable for any suitable waveguide transition arrangement. All the above-described features for the first example and the second example are thus applicable also for this alternative waveguide transition arrangement 10T.
[0079] With reference to Figure 5-Figure 9, the present disclosure also relates to a radio unit component 330, 730, 800 comprising the waveguide transition arrangement 300, 700 as described herein and an integrated circuit (IC) 124, 324, 724 that is connected to the first signal conductor 113 and the beamlead conductors 114A, 114B. The integrated circuit 124, 324, 724 may for example be of the type Radio Frequency Integrated Circuit (RFIC).
[0080] The first signal conductor 113and the beamlead conductors 114A, 114B are connected to IC bond pads forming a ground-signal-ground connection. The beamlead conductors 114A, 114B to the IC 724 may be omitted if the IC 724 has backside ground. The second layer structure 706 has a waveguide aperture 712, a trench 709 for the airsuspended first layer structure 703, an IC cavity 725 adapted to accommodate the IC 724, and conductor lines 731 for e.g. DC, IF, and local oscillator (LO) signals. On top of the waveguide aperture 712, a backshort 719 is placed.
[0081] The IC 724 is placed in the IC cavity 725 such that the top surfaces of the second dielectric carrier material 707 and the IC 724 align. The depth of the IC cavity 725 can either extend partly through the second dielectric carrier material 707 such that the IC 724 rests on the second dielectric carrier material, or the depth can extend through the entire second dielectric carrier material 707 such that the IC 724 rests on the material below the second dielectric carrier material.
[0082] This means that in the case of the alternative waveguide transition arrangement 101' described above where there is a first signal conductor 113A and a second signal conductor 113B, the signal conductors 113A, 113B and the beamlead conductors 114A, 114B are connected to a differential IC 124'.
[0083] According to some aspects, as shown in Figure 7 and Figure 8, the second metallization layer 708 comprises bias conductors 731 that are connected to the integrated circuit 724. In this manner, bias conductors 731 are integrated into the design of the second layer structure 706.
[0084] According to some aspects, as shown in Figure 8 and an exploded view in Figure 9, the radio unit component 800 further comprises a cover housing part 732 such that a system-on-chip, SoC, device 800 is formed. Such an SoC device 800 is for example suitable for a pick-and-place manufacturing process.
[0085] With reference to Figure 10, the present disclosure also relates to a radio unit 900 comprising the radio unit component 800 as described herein.
[0086] According to some aspects, the present disclosure is applicable for many types of microwave applications.
Claims
CLAIMS1 . A waveguide transition arrangement (300, 700) for coupling a signal between a transmission line (120, 320) and a waveguide aperture (112, 312, 712), where the transition arrangement (300) comprises- an electrically conductive backshort (319, 719),- a first layer structure (103, 703) comprising a first dielectric carrier material (104) and a first metallization layer (105), and- a second layer structure (106, 306, 706) comprising a second dielectric carrier material (107, 307), a second metallization layer (108, 308), a trench (109, 309, 709) provided with electrically conductive trench walls (110, 111 ; 318), and a waveguide aperture (112, 312, 712) that is connected to the trench (109, 309, 709), comprises electrically conductive inner waveguide walls (321), and defines a waveguide that has a signal propagation extension (E) into the second layer structure (106, 306, 706), where:- the first metallization layer (105) comprises a probe (116, 116A), a first signal conductor (113, 133A), and a pair of beamlead conductors (114A, 114B) that are formed on each side of the first signal conductor (113, 113A), wherein the first signal conductor (113, 113A) is comprised in the transmission line (120, 320), and wherein an end of the first signal conductor (113, 133A) is connected to the probe (116, 116A);- the second metallization layer (108, 308) comprises trench side conductors (115A, 115B; 315A, 315B) that are formed on opposite sides along the trench (109, 309, 709), and an aperture conductor (117, 317) that partially circumvents the waveguide aperture (112, 312, 712);- the first layer structure (103, 703) is arranged relative the second layer structure (106, 306, 706) such that the respective beamlead conductors (114A, 114B) are connected to the respective trench side conductors (115A, 115B; 315A, 315B), such that the first layer structure (103, 703) at least partly closes the trench (109, 309, 709), such that the first signal conductor (113, 113A) runs along to the trench (109, 309, 709), and such that the probe (116, 116A) is configured to couple the signal between the transmission line and a waveguide mode into or from the waveguide aperture (112, 312, 712); and where- the backshort (319, 719) is connected to the aperture conductor (117, 317).
2. The waveguide transition arrangement (300, 700) according to claim 1 , wherein the trench walls (110, 111) comprise first vias (110) and an electrically conductive layer (111) that is comprised in the second layer structure (106, 306, 706), the first vias (110) being connected to the electrically conductive layer (111).
3. The waveguide transition arrangement (300, 700) according to claim 1 , wherein the trench walls (318) comprise a trench wall metallization (318) that is formed in the trench (309).
4. The waveguide transition arrangement (300, 700) according to any one of the previous claims, wherein each of the first and the second dielectric carrier materials (104, 107; 307) is made in an organic or ceramic material, and where the thickness (t) of the first dielectric carrier material (104) falls below 0,1 A, and more preferably falls below 0, 057, where A is a wavelength that corresponds to a center frequency in a frequency band of operation.
5. The waveguide transition arrangement (300, 700) according to any one of the previous claims, wherein the backshort (319, 719) comprises a backshort aperture (322) through which the first signal conductor (113, 113A) passes into an interior cavity (323) of the backshort (319, 719) from outside the interior cavity (323) such that the first signal conductor (113, 113A) and the probe (116, 116A) extends across a part of the waveguide aperture (112, 312, 712).
6. The waveguide transition arrangement (300, 700) according to claim 5, wherein the first dielectric carrier material (104) only extends until the trench (109, 309, 709) connects to the waveguide aperture (112, 312, 712).
7. The waveguide transition arrangement (300, 700) according to any one of the claims 5 or 6, wherein the backshort aperture (322) has an inner width (wt>) that presents a cut-off frequency for higher waveguide modes relative to a frequency band of operation of the waveguide transition arrangement.
8. The waveguide transition arrangement (300, 700) according to any one of the claims 5-7, wherein the backshort aperture (322) is aligned with the trench (109, 309, 709).
9. The waveguide transition arrangement (300, 700) according to any one of the previous claims, being adapted for a center frequency in a frequency band of operation that at least partly lies within 130GHz-174.8GHz and / or higher frequency bands.
10. The waveguide transition arrangement (300, 700) according to any one of the previous claims, wherein the first metallization layer (105) comprises a second signal conductor (113B), wherein the first and the second signal conductors (113A, 113B) are positioned between the beamlead conductors (114A, 114B) and are comprised in the transmission line, and wherein a corresponding probe (116A, 116B) is connected to the first and the second signal conductors (113A, 113B).11 . The waveguide transition arrangement (300, 700) according to any one of the previous claims, wherein the waveguide aperture (112, 312, 712) defines a waveguide that has a signal propagation extension (E) perpendicular to a plane (P) that runs through the second metallization layer (108, 308).
12. The waveguide transition arrangement (300, 700) according to any one of the previous claim, wherein the transmission line (120, 320) is a planar transmission line.
13. The waveguide transition arrangement (300, 700) according to any one of the previous claim, wherein the first metallization layer (105) and the second metallization layer (108, 308) are mutually parallel.
14. The waveguide transition arrangement (300, 700) according to any one of the previous claim, wherein the probe (116; 116A, 116B) is configured to couple the signal between the transmission line (120, 320) and a first order Transverse Electric, TE01 , mode into or from the waveguide aperture (112, 312).
15. The waveguide transition arrangement (300, 700) according to any one of the previous claim, wherein the first signal conductor (113, 113A), together with the beamlead conductors (114A, 114B) and / or the trench walls (110, 111 ; 318) are comprised in the transmission line (120, 320),16. The waveguide transition arrangement (300, 700) according to any one of the previous claims, wherein the trench (109, 309, 709) has an inner trench width (wt) that presents a cut-off frequency for higher waveguide modes relative to a frequency band of operation of the waveguide transition arrangement.
17. A radio unit component (330, 730, 800) comprising the waveguide transition arrangement (300, 700) according to any one of the previous claims and an integrated circuit (124, 324, 724) that is connected to the first signal conductor (113; 113A, 113B) and the beamlead conductors (114A, 114B).
18. The radio unit component (800) according to claim 17, wherein the second metallization layer (108, 308) comprises bias conductors (731) that are connected to the integrated circuit (124, 324, 724).
19. The radio unit component (800) according to any one of the claims 17 or 18, further comprising a cover housing part (732) such that a system-on-chip, SoC, device (800) is formed.
20. A radio unit (900) comprising the radio unit component (800) according to any one of the claims 17-19.