High isolation conversion design for differential signal ports

Abstract

This document describes techniques, apparatus, and systems that utilize a high-isolation conversion design for a differential signal port. A differential input conversion structure includes a first layer and a second layer made of a conductive metal, and a substrate positioned between the first layer and the second layer. The second layer includes a first portion electrically connected to a single-ended signal contact and electrically connected to a first contact of the differential signal port. The first portion includes a first stub based on an input impedance of the single-ended signal contact and a second stub based on a differential input impedance associated with the differential signal port. The second layer includes a second portion electrically connected to a second contact of the differential signal port and electrically connected to the first layer through a via housed in a pad. The second portion includes a third stub associated with the differential input impedance.

Description

BACKGROUND

[0001] Some devices (e.g., radars) use electromagnetic signals to detect and track objects. For example, many devices include monolithic microwave integrated circuits (MMICs) on printed circuit boards (PCBs) for analog signal processing of microwave and / or radar signals, such as power amplification, mixing, etc. Substrate integrated waveguides (SIWs) provide a low-cost and production-friendly mechanism for routing microwave and / or radar signals between the MMICs and antennas. However, connecting MMIC signal ports to SIWs presents challenges. To illustrate, MMICs typically include differential signal ports for receiving and / or transmitting signals, while SIWs propagate single-ended signals. To conserve space on the PCB, the differential signal ports of the MMICs can be positioned close together, which can cause RF power leakage between channels and signal degradation. Shielding structures further exacerbate the problem by reflecting the radiated signals back to the source, causing further signal degradation, which adversely affects the detection / tracking accuracy and field of view of the radar signals. SUMMARY

[0002] This document describes techniques, apparatuses, and systems that leverage a high-isolation transition design for differential signal ports. In aspects, a differential input transition structure includes a first layer made of a conductive metal and positioned at a bottom of the differential input transition structure. The differential input transition structure also includes a substrate positioned above (and adjacent to) the first layer and a second layer made of a conductive metal, where the differential input transition structure positions the second layer above and adjacent to the substrate. The second layer of the differential input transition structure includes a first portion formed to electrically connect a substrate integrated waveguide (SIW) to a first contact point of a differential signal port, the first portion including a first stub based on an input impedance of the SIW and a second stub based on a differential input impedance associated with the differential signal port. The second layer of the differential input transition structure also includes a second portion separate from the first portion, where the second portion is formed to electrically connect to a second contact point of the differential signal port and to the first layer through a via. The second portion includes a third stub associated with the differential input impedance and a pad to electrically connect the via to the second layer.

[0003] This summary introduces simplified concepts related to a high-isolation transition design for differential signal ports, which are further described in the DETAILED DESCRIPTION and the accompanying drawings. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for determining the scope of the claimed subject matter. BRIEF DESCRIPTION OF DRAWINGS

[0004] Details of techniques, apparatuses, and systems that utilize high-isolation transition designs for differential signal ports are described in this document with reference to the following drawings. Like numbers refer to like features throughout the drawings:

[0005] Figure 1 An example system including a differential input transition structure is shown in accordance with the techniques, apparatuses, and systems of this disclosure;

[0006] Figure 2 An example system including a differential input transition structure is shown in accordance with the techniques, apparatuses, and systems of this disclosure;

[0007] Figure 3 An example printed circuit board (PCB) including a MMIC, one or more substrate integrated waveguides (SIWs), and one or more differential input transition structures is shown in accordance with the techniques, apparatuses, and systems of this disclosure; and

[0008] Figure 4 An example system including one or more differential input transition structures is shown in accordance with the techniques, apparatuses, and systems of this disclosure. DETAILED DESCRIPTION

[0009] SUMMARY

[0010] Many industries use radar systems as a sensing technology, including the automotive industry, to acquire information about the surrounding environment. Some radar systems include one or more monolithic microwave integrated circuits (MMICs) on a printed circuit board (PCB) for processing microwave and / or radar signals. To illustrate, an antenna receives an over-the-air radar signal, which is then routed through a substrate integrated waveguide (SIW) to a receiver port of the MMIC for processing, such as mixing to down-convert the received signal to an intermediate frequency (IF) signal, amplifying power of the transmitted signal, etc. Thus, the SIW routes the signal between the antenna and the MMIC signal port.

[0011] Connecting the MMIC signal port to the SIW presents challenges. To illustrate, the MMIC typically implements the signal port as a differential signal port, while the SIW propagates a single-ended signal. Generally, a differential signal corresponds to a pair of differential signals, where signal processing focuses on the electrical difference between the pair of signals, as opposed to the electrical difference between a single signal and a ground plane. In contrast, a single-ended signal corresponds to a single signal with reference to a ground plane. A transition structure connects the differential signal to the single-ended signal and / or vice versa. As one example, a transition structure connects a MMIC differential signal port to a single-ended SIW signal port. Alternatively or additionally, other examples include (by way of example and not limitation) air waveguides that feed differential antennas (e.g., for cellular communications), low voltage differential signaling systems (LVDS), high voltage (HVD) signaling systems, audio systems, display devices, etc.

[0012] When used on a PCB, many factors can affect how well the transition structure performs. To illustrate, PCBs are often space constrained, which can result in a compact design. An MMIC that includes multiple differential signal ports can position the differential signal ports close together. Poor isolation between the differential signal ports, and the transition structure connecting the differential signal ports to the SIW, can result in RF power leakage between different signals and degrade signal quality. Shielding structures exacerbate the problem by reflecting (leaking) the radiated signal back to the source, resulting in further signal degradation that adversely impacts radar signal detection / tracking accuracy and field of view. Placing the MMIC and antenna on opposite sides of the PCB also presents challenges. Vertical transition structures used to route signals through the PCB can result in unwanted radio frequency (RF) power loss. Moreover, vertical transition structure designs utilize multiple PCB layers (e.g., greater than two), which increases cost as more layers are added to the vertical transition structure.

[0013] This document describes techniques, apparatuses, and systems that utilize a high-isolation transition design for differential signal ports (also referred to as a differential input transition structure). In aspects, a first layer of conductive metal, a second layer of conductive metal, and a substrate positioned between the first layer and the second layer form a two-layer, horizontal differential input transition structure that provides high isolation between channels and mitigates RF leakage that degrades signal quality. The two-layer, horizontal differential input transition structure also accommodates PCB configurations that place the MMIC and antenna on the same side, thereby mitigating unwanted RF power loss. Using two layers also helps reduce production costs relative to using multiple PCB layers (e.g., greater than two). In other aspects, the differential input transition structure can be implemented using a single layer of low temperature co-fired ceramic (LTCC) material that feeds electromagnetic signals to other LTCC structures (e.g., antennas, laminated waveguides).

[0014] As one example of a differential input transition structure, a second layer of a two-layer, horizontal differential input transition structure includes a first portion formed to electrically connect a SIW to a first contact point of a differential signal port, where the first portion includes (i) a first stub based on an input impedance of the SIW and (ii) a second stub based on a differential input impedance associated with the differential signal port. The second layer of the two-layer, horizontal differential input transition structure also includes a second portion formed to electrically connect to a second contact point of the differential signal port and to the first layer through a via. In aspects, the second portion includes a third stub associated with the differential input impedance and a pad that electrically connects the via to the second layer. This is just one example of the techniques, apparatuses, and systems described for a high-isolation transition design for differential signal ports. This document describes other examples and implementations.

[0015] Example system

[0016] Figure 1 An example system 100 including a differential input conversion structure is shown in accordance with the techniques, apparatus, and systems of the present disclosure. The system includes a device 102 formed using a first layer 104, a substrate 106, and a second layer 108. The system uses conductive material and / or metal as the first layer 104 and the second layer 108, which can include one or more of copper, gold, silver, tin, nickel, metal compounds, conductive ink, and the like. In some aspects, the first layer of conductive material (e.g., layer 104) includes a ground plane. The substrate 106 includes a dielectric material, such as a laminate (e.g., Rogers RO3003), germanium, silicon, silicon dioxide, aluminum oxide, and the like.

[0017] The system 100 includes a two-layer, horizontal differential input conversion structure 110 (differential input conversion structure 110) composed of the first layer 104, the substrate 106, and the second layer 108. To illustrate, the differential input conversion structure uses the second layer 108 to form a first portion 112 and a second portion 114. The first portion includes a stub 116 having a size and / or shape based on impedance characteristics of a contact point, shown here as a substrate integrated waveguide 118 (SIW). For example, the shape, size, and / or form of the SIW 118 (e.g., number of vias included, spacing between vias) can be based on an operating frequency and / or frequency range of a signal routed by the SIW. In turn, this can affect the shape and / or size of the stub 116. In aspects, the differential input conversion structure 110 places the stub 116 at an entrance of the SIW 118. The second portion 114 uses vias 120 and pads 122 to electrically connect the second layer 108 to the first layer 104. Because the vias 120 connect to both the second layer 108 and the first layer 104, and assuming the first layer 104 includes a ground plane, the vias 120 route the signal to the ground plane, which forces a 180° phase shift and allows for conversion between a single-ended signal and a differential signal. In other words, the introduction of the 180° phase shift allows the differential signal to be added together at a common point. The differential input conversion structure 110 also separates the second portion 114 or pads 112 from the SIW 118 such that the pads 122 are disconnected (electrically disconnected) from and separated from the SIW 118. The portion of the second layer forming the second portion of the differential input conversion structure 110 and / or the pads do not physically contact the portion of the second layer forming the SIW 118.

[0018] Figure 2 A partial view of an example system 200 including a differential input conversion structure 202 implemented using aspects of a high-isolation conversion design for differential signal ports is shown. Some aspects use aspects described with respect to Figure 1The differential input conversion structure 202 is implemented using the techniques described for the two-layer, horizontal differential input conversion structure 110 of FIG. 1. In the system 200, a first end of the differential input conversion structure 202 is connected to the SIW 204, and a second end of the differential input conversion structure 202 is connected to the differential signal port 206 of the MMIC 208. In other words, the differential input conversion structure 202 uses the differential signal port 206 to connect and route signals between the SIW 204 and the MMIC 208.

[0019] The first portion 210 of the differential input conversion structure (e.g., formed using the second layer of the PCB) includes a first stub 212 placed at an entrance of the SIW 204 and a second stub connected to a first signal ball 216 of the differential signal port 206. The second portion 218 of the differential input conversion structure 202 (e.g., also formed using the second layer of the PCB) includes a third stub 220 and a pad 222. The third stub 220 is connected to a second signal ball 224 of the differential signal port 206, and the pad 222 electrically connects the second layer of the PCB to the first layer of the PCB (not shown) using a via 226. The first signal ball 216 and the second signal ball 224 are electrically connected to each other using the differential signal port 206. Figure 2 The connections in the MMIC 208 are shown using dashed lines to represent that these connections are within and / or part of the MMIC 208. Similar to the description of FIG. 1, the differential input conversion structure 202 is electrically connected to the SIW 204 and the MMIC 208. Figure 1 Similar to the description of FIG. 1, the pad 222 and the SIW 204 are disconnected from each other.

[0020] The size and / or shape of the stub 212 can be based on a combination of factors. To illustrate, the stub 212 has a rectangular shape with a width 228 and a height 230 that are based on an input impedance of the SIW 204. Alternatively or additionally, the size and / or shape of the stub 212 can be based on: a material of a substrate (e.g., the substrate 106) used to form the differential input conversion structure 202; a dielectric property of the substrate; an operating frequency of a signal converted by the differential input conversion structure 202 (e.g., an operating frequency of the differential signal port 206 and / or the SIW 204); a combined thickness of the first layer, the substrate, and the second layer used to form the differential input conversion structure 202; and / or the like. As one example, the width 228 generally has a length of 0.42 millimeters (mm), and the height 230 generally has a length of 0.43 mm. The term “generally” indicates that real-world implementations can be above or below the absolute and exact values within an error threshold. To illustrate, the width 228 can be 0.42 mm within an error threshold, and the height 230 can be 0.43 mm within an error threshold.

[0021] In aspects, the size and / or shape of the pads 222 can be based on the size and / or shape of the vias 226. For example, in the system 200, the pads 222 have a rectangular shape with a width 232 and a height 234, where the width 232 generally has a length of 0.35 millimeters (mm) and the height 234 generally has a length of 0.35 mm, each within an error threshold. In aspects, the error threshold corresponds to an error percentage, such as a 0.1% error, a 0.5% error, a 1% error, a 5% error, and the like.

[0022] The size and shape of the stubs 214 and / or 220 can alternatively or additionally be based on any combination of the differential signal port 206 input impedance, the substrate material, the dielectric properties of the substrate, the thickness of the PCB used to implement the differential input conversion structure 202, the frequency of operation of the differential input conversion structure 202, the SIW 204, and / or the differential signal port 206, and the like. Some aspects collectively determine the size and / or shape of the stubs 214 and 220. In other words, the size and / or shape of the stubs 214 and 220 are dependent on one another. As one example, the size and / or shape of the stubs 214 and 220 are based on a quarter-wave impedance transformer collectively forming for microwave and / or radar signals transmitted / received by the MMIC 208 through the signal balls 216 and 224. Example frequency ranges include the millimeter wave band defined as 40-100 gigahertz (GHz), the Ka band defined as 25.5-40 GHz, the K band defined as 18-26.6 GHz, and the Ku band defined as 12.5-18 GHz.

[0023] Figure 3 A partial view of an example system 300 including differential input conversion structures in accordance with the techniques, apparatus, and systems of this disclosure is shown. The example system 300 includes a MMIC 302 embedded on a PCB 304 having a plurality of differential signal ports, three transmit differential signal ports 306 and four receive differential signal ports 308. Each differential signal port of the MMIC 302 is connected to a respective SIW using a band-delayed balun structure or a differential input conversion structure. As described further below, the combination and placement of the differential input conversion structures and the band-delayed balun structures helps to improve isolation between transmit and / or receive channels.

[0024] A transmit substrate integrated waveguide 310 (TX SIW 310) is connected to a first delay-balun structure 312, a transmit substrate integrated waveguide 314 (TX SIW 314) is connected to a first differential-input conversion structure 316, and a transmit substrate integrated waveguide 318 (TX SIW 318) is connected to a second delay-balun structure 320. The first delay-balun structure 312, the first differential-input conversion structure 316, and the second delay-balun structure 320 are each connected to a respective pair of transmit differential signal balls of the transmit differential signal port 306. In a similar manner, a receive substrate integrated waveguide 322 (RX SIW 322), a receive substrate integrated waveguide 324 (RX SIW 324), a receive substrate integrated waveguide 326 (RX SIW 326), and a receive substrate integrated waveguide 328 (RX SIW 328) are each connected to a respective pair of receive differential signal balls of the receive differential signal port 308 using a delay-balun structure or a differential-input conversion structure, respectively. Each connection to a SIW (e.g., receive SIW, transmit SIW), whether using a differential-input conversion structure or a delay-balun structure, corresponds to a single-ended signal connection. Similarly, each connection to a differential signal port, whether using a differential-input conversion structure or a delay-balun structure, corresponds to a differential signal connection.

[0025] The combination and placement of differential-input conversion structures and delay-balun structures helps to improve isolation between signal channels. As one example, the combination shown in the image 330 places structures with different radiation patterns adjacent to one another to reduce RF coupling. The image 330 represents a magnified view of receive-side functionality included in the system 300. The receive differential signal port 308 is labeled as receive differential signal port 332, receive differential signal port 334, receive differential signal port 336, and receive differential signal port 338, respectively. These connections are shown as dashed lines to represent that the signal ports are within and / or part of the MMIC 302. While the image 330 illustrates receive-side functionality, the various aspects described can alternatively or additionally relate to transmit-side functionality.

[0026] A third delay-balun structure 340 of the system 300 connects to the RX SIW 322 and the receive differential signal port 332 using a first portion 342 and a second portion 344. The first portion 342 includes a delay line that introduces a 180° phase shift in the signal carried by the first portion, as well as a stub (e.g., an impedance-matched stub), while the second portion 344 includes a stub. The 180° phase shift allows the differential signals to be added together at a common point. The system 300 also positions a second differential-input conversion structure 346 adjacent to the delay-balun structure 340. In some aspects, the second differential-input conversion structure 346 is positioned to be within 1 mm of the delay-balun structure 340. The second differential-input conversion structure 346 includes a delay line that introduces a 180° phase shift in the signal carried by the second differential-input conversion structure 346, as well as a stub (e.g., an impedance-matched stub). The 180° phase shift allows the differential signals to be added together at a common point. Figure 2The differential input conversion structure 346 corresponds to the differential input conversion structure 202 of FIG. 2. The differential input conversion structure 346 is connected to the RX SIW 324 and the receive differential signal port 334. Because the band-delayed balun structure 340 has a different radiation pattern than the second differential input conversion structure 346, positioning the two structures adjacent to each other reduces coupling between signals propagating with the radiation patterns and helps improve channel isolation, reduce RF leakage between channels, and improve signal quality. This also improves detection accuracy calculated by analyzing the signals. While described with reference to receive-side functionality, this positioning alternatively or additionally reduces transmit-side coupling between signals, as shown by the placement of the first band-delayed balun structure 312, the first differential input conversion structure 316, and the second band-delayed balun structure 320.

[0027] On the receive side, the third differential input conversion structure 348 and the fourth band-delayed balun structure 350 mirror the positioning of the second differential input conversion structure 346 and the third band-delayed balun structure 340. The third differential input conversion structure 348 is connected to the RX SIW 326 and the receive differential signal port 336, while the fourth band-delayed balun structure 350 is connected to the RX SIW 328 and the receive differential signal port 338. Because the second differential input conversion structure 346 and the third differential input conversion structure 348 are positioned adjacent to each other, mirroring or flipping portions of the positions helps improve channel isolation and reduce RF leakage between channels. To illustrate, because the second differential input conversion structure 346 and the third differential input conversion structure 348 have similar radiation patterns, flipping and / or mirroring portions of the placement helps separate the propagation of the radiation patterns and reduces RF leakage. The isolation between the second differential input conversion structure 346 and the third differential input conversion structure 348 can be proportional to the distance between respective vias of each differential input conversion structure (e.g., further distance improves isolation). Accordingly, the system 300 positions a first portion 352 of the differential input conversion structure 346 adjacent to a first portion 354 of the differential input conversion structure 348. This positions a second portion 356 of the differential input conversion structure 346 and a second portion 358 of the differential input conversion structure 348, which house respective vias, away from each other rather than adjacent to each other (e.g., like the first portions), and further improves isolation between channels.

[0028] While the example 300 illustrates a combination of differential input conversion structures and band-delayed balun structures, alternative implementations can use only differential input conversion structures. For example, with reference to the image 330, some implementations can replace the band-delayed balun structure 340 with a differential input conversion structure whose portions of placement can mirror those of the differential input conversion structure 346 and / or replace the band-delayed balun structure 350 with a differential input conversion structure whose portions of placement can mirror those of the differential input conversion structure 348.

[0029] Figure 4 An example system 400 including one or more differential input conversion structures using aspects of a high-isolation conversion design for differential signal ports is shown. Figure 4 A partial view 402 of the system 400 and a side view 404 of the system 400 are included. As shown in the partial view 402, the system 400 includes a shielding structure 406 covering the MMIC 408 on the PCB 410. In some aspects, the system places a thermally and electromagnetically absorbing material and / or a radio frequency (RF) absorber (not shown) on the MMIC 408 such that the shielding structure 406 covers the MMIC 408 as well as the thermally and electromagnetically absorbing material. Any suitable type of material can be used to form the shielding structure, such as any suitable metal (e.g., copper, aluminum, carbon steel, pre-tinned steel, zinc, nickel, nickel silver). Similarly, any suitable metal can be used for the thermally and electromagnetically absorbing material, such as a dielectric foam absorber, a polymer-based material, a magnetic absorber, etc. Lines 412 provide additional reference for MMIC package port locations.

[0030] The shielding structure 406 also covers the transmit differential signal ports 414, the receive differential signal ports 416, the transmit sideband delay baluns and / or differential input conversion structures 418, and the receive sideband delay baluns and / or differential input conversion structures 420. In some aspects, the shielding structure 406 covers portions of the SIWs. To illustrate, the PCB 410 includes three transmit SIWs (represented by reference line 422) and four receive SIWs (represented by reference line 424). Each transmit SIW is connected to a respective structure of the transmit sideband delay baluns and / or differential input conversion structures 418 and an antenna having transmit capabilities. Similarly, each receive SIW is connected to a respective structure of the receive sideband delay baluns and / or differential input conversion structures 420 and an antenna having receive capabilities. In aspects, the shielding structure 406 covers a portion of each receive SIW and transmit SIW (e.g., the portion connected to the respective band delay balun and / or differential input conversion structure). Thus, the shielding structure 406 covers the MMIC 408 and various structures for connecting single-ended signals to differential signals. Alternatively or additionally, the shielding structure 406 covers the thermally and electromagnetically absorbing material, as further described. In some aspects, the MMIC 408, transmit differential signal ports 414, receive differential signal ports 416, transmit sideband delay baluns and / or differential input conversion structures 418, receive sideband delay baluns and / or differential input conversion structures 420, transmit SIWs, and receive SIWs are in reference to the shielding structure 406. Figure 3 The described correspond to those described.

[0031] The shield structure 406 shown in the example system 400 has a rectangular shape with a width 426 and a height 428. However, any other suitable geometry can be utilized. In one example, the width 426 generally has a length of 15.2 mm within an error threshold, and the height 428 generally has a length of 15.2 mm within an error threshold. In some aspects, the error threshold corresponds to an error percentage, such as a 0.1% error, a 0.5% error, a 1% error, a 5% error, and the like.

[0032] The side view 404 shows an expanded and rotated view of a portion of the system 400. The side view 404 includes the shield structure 406, the PCB 410, and the metal lid 432. As further shown, the shield structure 406 has a thickness 434. In one example, the thickness 434 generally has a length of 1.85 mm within an error threshold. In some aspects, the error threshold corresponds to an error percentage, such as a 0.1% error, a 0.5% error, a 1% error, a 5% error, and the like.

[0033] The two-layer, horizontal differential input structure (e.g., differential input transition structure) provides high isolation between channels for differential signals to single-ended signals and mitigates RF leakage that degrades signal quality. The two-layer, horizontal differential input transition structure also accommodates PCB configurations that place MMICs and antennas on the same side and mitigates unwanted RF power loss. Using two layers also helps reduce production costs by reducing the number of layers included in the design relative to using multiple PCB layers (e.g., greater than two). However, in other aspects, the differential input transition structure can be implemented using a single layer of low temperature co-fired ceramic (LTCC) material that feeds electromagnetic signals to other LTCC structures (e.g., antennas, laminated waveguides). In some aspects, placing the differential input transition structure adjacent other transition structures, such as a band-delayed balun structure, reduces RF coupling by placing different radiation patterns adjacent to each other. However, alternative implementations use only the differential input transition structure.

[0034] Additional Examples

[0035] In the following sections, additional examples of high-isolation transition designs for differential signal ports are provided.

[0036] Example 1 : A differential input conversion structure comprising: a first layer made of a conductive metal and positioned at a bottom of the differential input conversion structure; a substrate positioned above and adjacent to the first layer; and a second layer made of a conductive metal and positioned above and adjacent to the substrate, the second layer comprising: a first portion shaped to electrically connect a single-ended signal contact to a first contact of a differential signal port, the first portion comprising a first stub based on an input impedance of an SIW and a second stub based on a differential input impedance associated with the differential signal port; and a second portion separate from the first portion, the second portion shaped to electrically connect to a second contact of the differential signal port and to the first layer through a via, the second portion comprising a third stub associated with the differential input impedance and a pad electrically connecting the via to the second layer.

[0037] Example 2: The differential input conversion structure of example 1, wherein the second portion of the second layer is disconnected from and separate from the single-ended signal contact.

[0038] Example 3: The differential input conversion structure of any of the preceding examples, wherein the second stub of the first portion and the third stub of the second portion form a quarter-wave impedance transformer.

[0039] Example 4: The differential input conversion structure of any of the preceding examples, wherein the quarter-wave impedance transformer is based on a waveform in a frequency range of 70 to 85 gigahertz (GHz).

[0040] Example 5: The differential input conversion structure of any of the preceding examples, wherein the via connecting the second layer to the first layer and the pad shaped to surround the via are positioned at an entrance of a substrate integrated waveguide (SIW), the SIW being the single-ended signal contact.

[0041] Example 6: The differential input conversion structure of any of the preceding examples, wherein the differential input impedance is based on a monolithic microwave integrated circuit (MMIC) transmitter or receiver port.

[0042] Example 7: The differential input conversion structure of any of the preceding examples, wherein a size of the first stub, the second stub, or the third stub is based on at least one of: an operating frequency of the differential signal port or the single-ended signal contact; a combined thickness of the first layer, the substrate, and the second layer; or a material of the substrate.

[0043] Example 8: The differential input conversion structure of any of the preceding examples, wherein the first stub has a rectangular shape, a width of the first stub is 43 millimeters (mm) within an error threshold, and a height of the first stub is 43 mm within the error threshold.

[0044] Example 9: A system comprising: a monolithic microwave integrated circuit (MMIC) having one or more differential signal ports; one or more substrate integrated waveguides (SIWs); one or more delay-balun structures; and one or more differential input conversion structures, each differential input conversion comprising: a first layer made of electrically conductive metal and positioned at a bottom of the differential input conversion structure; a substrate positioned above and adjacent to the first layer; and a second layer made of electrically conductive metal and positioned above and adjacent to the substrate, the second layer comprising: a first portion electrically connecting a respective SIW of the one or more SIWs to a respective differential signal port of the one or more differential signal ports, the first portion comprising a first stub based on a SIW input impedance of the respective SIW and a second stub based on a differential input impedance of the respective differential signal port; and a second portion separate from the first portion, the second portion electrically connected to the respective differential signal port and to the first layer through a via, the second portion comprising a third stub associated with the differential input impedance of the respective differential signal port and comprising a pad shaped to enclose the via.

[0045] Example 10: The system of any of the preceding examples, wherein the system comprises: a first delay-balun structure of the one or more delay-balun structures connected to a first differential signal port of the one or more differential signal ports of the MMIC; and a first differential input conversion structure of the one or more differential input conversion structures connected to a second differential signal port of the one or more differential signal ports of the MMIC, wherein the first differential signal port is positioned adjacent to the second differential signal port, and wherein the first delay-balun structure is positioned adjacent to the first differential signal input conversion structure.

[0046] Example 11: The system of any of the preceding examples, wherein: the first differential signal port is a first transmit port of the MMIC, the second differential signal port is a second transmit port of the MMIC, the first delay-balun structure connects the first transmit port to a first SIW of the one or more SIWs, and the first differential signal port connects the second transmit port to a second SIW of the one or more SIWs.

[0047] Example 12: The system of any of the preceding examples, wherein: the first differential signal port is a first receive port of the MMIC, the second differential signal port is a second receive port of the MMIC, the first delay-balun structure connects the first receive port to a first SIW of the one or more SIWs, and the first differential signal port connects the second receive port to a second SIW of the one or more SIWs.

[0048] Example 13: The system of any of the preceding examples, wherein the system further comprises: a second differential input conversion structure of the one or more differential input conversion structures, the second differential input conversion structure connecting a third differential signal port of the one or more differential signal ports of the MMIC to a third SIW of the one or more SIWs, the third differential signal port being a third receive port of the MMIC; wherein the second differential input conversion structure is positioned adjacent to the first differential input conversion structure, and wherein the second differential input conversion structure is flipped relative to the first differential input conversion structure such that: the first portion of the first differential input conversion structure is positioned adjacent to the first portion of the second differential input conversion structure; and the second portion of the first differential input conversion structure is positioned adjacent to the first delay-balun structure.

[0049] Example 14: The system of any of the preceding examples, wherein the system comprises: a second delay-balun structure of the one or more delay-balun structures, the second delay-balun structure connecting a fourth differential signal port of the one or more differential signal ports of the MMIC to a fourth SIW of the one or more SIWs, the fourth differential signal port being a fourth receive port of the MMIC, wherein the second delay-balun structure is positioned adjacent to the second portion of the second differential input conversion structure.

[0050] Example 15: The system of any of the preceding examples, further comprising: a metal shield positioned over the MMIC, the one or more delay-balun structures, and the one or more differential input conversion structures.

[0051] Example 16: The system of any of the preceding examples, wherein the dimensions of the shield comprise: a width of 15.2 millimeters (mm) within an error threshold; and a length of 15.2 mm within the error threshold.

[0052] Example 17: The system of any of the preceding examples, wherein for at least one differential input conversion structure of the one or more differential input conversion structures, the second stub of the first portion and the third stub of the second portion combine to form a quarter-wave impedance transformer.

[0053] Example 18: The system of any of the preceding examples, wherein the second stub of the first portion and the third stub of the second portion combine to form a quarter-wave impedance transformer based on a waveform within a frequency range of 70 to 85 gigahertz (GHz).

[0054] Example 19: The system of any of the preceding examples, wherein for at least one differential input conversion structure of the one or more differential input conversion structures, the system positions the pad and the via of the second portion at an entrance of at least one SIW of the one or more SIWs.

[0055] Example 20: The system of any of the preceding examples, wherein for at least one of the one or more differential input conversion structures, the first stub included in the first portion has dimensions comprising: a width of 0.42 millimeters (mm) within an error threshold; and a length of 0.43 mm within the error threshold.

[0056] CONCLUSION

[0057] While various embodiments of the present disclosure have been described and illustrated in the foregoing description, it is understood that the present disclosure is not limited to the embodiments described and illustrated herein but can be embodied in various ways within the scope of the claims that follow. It will be apparent from the foregoing description that various changes can be made without departing from the spirit and scope of the present disclosure as defined by the following claims.

[0058] The use of “or” and grammatically related terms herein is intended to encompass the meaning of “and / or” unless the context clearly dictates otherwise. As used herein, the phrase “at least one of a list of items refers to any combination of those items, including single members. As an example, “at least one of a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c, or any other ordering of a, b, and c).

Claims

1. A differential input conversion structure comprising: a first layer made of a conductive metal and positioned at a bottom of the differential input conversion structure; a substrate positioned above and adjacent to the first layer; and a second layer made of the conductive metal and positioned above and adjacent to the substrate, the second layer comprising: a first portion formed to electrically connect a single-ended signal contact to a first contact of a differential signal port, the first portion comprising a first stub based on an input impedance of the single-ended signal and a second stub based on a differential input impedance associated with the differential signal port; and a second portion separate from the first portion, the second portion formed to electrically connect a second contact of the differential signal port and to the first layer through a via, the second portion comprising a third stub associated with the differential input impedance and a pad electrically connecting the via to the second layer. The second portion of the second layer is disconnected from and separate from the single-ended signal contact. The second stub of the first portion and the third stub of the second portion form a quarter-wave impedance transformer.

2. The differential input conversion structure of claim 1, wherein, The quarter-wave impedance transformer is based on a waveform in a frequency range of 70 to 85 gigahertz (GHz).

3. The differential input conversion structure of claim 1, wherein, The via connecting the second layer to the first layer and the pad shaped to enclose the via are positioned at an entrance of a substrate integrated waveguide (SIW), wherein the SIW is a single-ended signal contact.

4. The differential input conversion structure of claim 3, wherein, The differential input impedance is based on a monolithic microwave integrated circuit (MMIC) transmitter or receiver port.

5. The differential input conversion structure of claim 1, wherein, The first stub, the second stub, or the third stub has a dimension based on at least one of:

6. The differential input conversion structure of claim 1, wherein, an operating frequency of the differential signal port or the single-ended signal contact; 7. The differential input conversion structure of claim 1, wherein, a combined thickness of the first layer, the substrate, and the second layer; or a material of the substrate. The first stub has a rectangular shape, a width of the first stub is 43 millimeters within an error threshold, and a height of the first stub is 43 millimeters within the error threshold.

9. A radar system comprising:

8. The differential input conversion structure of claim 7, wherein, a monolithic microwave integrated circuit (MMIC) having one or more differential signal ports; one or more substrate integrated waveguides (SIWs); one or more band-delayed balun structures; and one or more differential input conversion structures each comprising: a first layer made of a conductive metal and positioned at a bottom of the differential input conversion structure; a substrate positioned above and adjacent to the first layer; and a second layer made of the conductive metal and positioned above and adjacent to the substrate, the second layer comprising: ​ ​ ​ a first portion electrically connecting a respective SIW of the one or more SIWs to a respective differential signal port of the one or more differential signal ports, the first portion including a first stub based on a SIW input impedance of the respective SIW and a second stub based on a differential input impedance of the respective differential signal port; and a second portion separate from the first portion, the second portion electrically connected to the respective differential signal port and to the first layer through a via, the second portion including a third stub associated with the differential input impedance of the respective differential signal port and including a pad shaped to enclose the via.

10. The radar system of claim 9, wherein, The system includes: a first delay-based balun structure of the one or more delay-based balun structures, the first delay-based balun structure connected to a first differential signal port of the one or more differential signal ports of the MMIC; and a first differential input conversion structure of the one or more differential input conversion structures, the first differential input conversion structure connected to a second differential signal port of the one or more differential signal ports of the MMIC, wherein the first differential signal port is positioned adjacent to the second differential signal port, and wherein the first delay-based balun structure is positioned adjacent to the first differential input conversion structure.

11. The radar system of claim 10, wherein: the first differential signal port is a first transmit port of the MMIC, the second differential signal port is a second transmit port of the MMIC, the first delay-based balun structure connects the first transmit port to a first SIW of the one or more SIWs, and the first differential signal port connects the second transmit port to a second SIW of the one or more SIWs.

12. The radar system of claim 10, wherein: the first differential signal port is a first receive port of the MMIC, the second differential signal port is a second receive port of the MMIC, the first delay-based balun structure connects the first receive port to a first SIW of the one or more SIWs, and the first differential signal port connects the second receive port to a second SIW of the one or more SIWs.

13. The radar system of claim 12, wherein, The system further includes: a second differential input conversion structure of the one or more differential input conversion structures, the second differential input conversion structure connecting a third differential signal port of the one or more differential signal ports of the MMIC to a third SIW of the one or more SIWs, the third differential signal port being a third receive port of the MMIC, wherein the second differential input conversion structure is positioned adjacent to the first differential input conversion structure, and wherein the second differential input conversion structure is flipped relative to the first differential input conversion structure, such that: the first portion of the first differential input conversion structure is positioned adjacent to the first portion of the second differential input conversion structure; and the second portion of the first differential input conversion structure is positioned adjacent to the second portion of the second differential input conversion structure. The second portion of the first differential input conversion structure is positioned adjacent to the first delay-balun structure.

14. The radar system of claim 13, wherein, The system includes: a second delay-balun structure of the one or more delay-balun structures, the second delay-balun structure connecting a fourth differential signal port of the MMIC to a fourth SIW of the one or more SIWs, the fourth differential signal port being a fourth receive port of the MMIC, wherein the second delay-balun structure is positioned adjacent to the second portion of the second differential input conversion structure.

15. The radar system of claim 9, further comprising: a metal shield positioned over the MMIC, the one or more delay-balun structures, and the one or more differential input conversion structures.

16. The radar system of claim 15, wherein, The shield has dimensions including: a width of 15.2 millimeters within an error threshold; and a length of 15.2 millimeters within the error threshold.

17. The radar system of claim 9, wherein, For at least one differential input conversion structure of the one or more differential input conversion structures, the second stub of the first portion and the third stub of the second portion combine to form a quarter-wave impedance transformer.

18. The radar system of claim 17, wherein, The second stub of the first portion and the third stub of the second portion combine to form a quarter-wave impedance transformer based on waveforms within a frequency range of 70 to 85 gigahertz (GHz).

19. The radar system of claim 9, wherein, For at least one differential input conversion structure of the one or more differential input conversion structures, the system positions the pad and the via of the second portion at an entrance of at least one SIW of the one or more SIWs.

20. The radar system of claim 9, wherein, For at least one differential input conversion structure of the one or more differential input conversion structures, the first stub included in the first portion has dimensions including: a width of 0.42 millimeters within an error threshold; and a length of 0.43 millimeters within the error threshold.

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