Hybrid compact differential i / q signal generator

Abstract

The present disclosure provides various techniques for implementing a hybrid differential in-phase / quadrature (I / Q) generator in an integrated circuit. A conductive layout on a substrate includes an I / Q generation core occupying a core footprint region and implemented as a transformer (TF)-based differential coupler formed by concentrically arranged conductive loop segments. A first coupled-line differential coupler stage is disposed around the I / Q generation core within a footprint region that includes the core footprint region, and includes an in-phase coupled-line coupler and a quadrature coupled-line coupler that receive differential in-phase and quadrature outputs from the I / Q generation core and provide corresponding differential outputs. Additional coupled-line differential coupler stages can be disposed around prior stages as outer-ring conductive structures to support multi-stage implementations without duplicating additional TF-based differential couplers. The coupled-line stages can be implemented coplanar and / or using vertically stacked metal layers, and grounded isolation conductors can be provided to improve isolation.

Description

Attorney Docket No. EMTAR8003WO PATENTHYBRID COMPACT DIFFERENTIAL l / Q SIGNAL GENERATORCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 752,582, filed January 31, 2025, titled “Miniaturized Low-Loss In-Phase and Quadrature Signal Generator Using Mixed-Type Cascaded Coupled Lines and Transformers,” the disclosure of which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] This present disclosure relates generally to analog and radio frequency (RF) electronic circuit design, and more specifically, to in-phase and quadrature signal generation using differential couplers implemented on integrated circuits.BACKGROUND

[0003] Radio frequency (RF) systems and their applications including, e.g., sixth-generation (6G) and beyond telecommunications networks, Wi-Fi systems, satellite and non-terrestrial networks (NTN), integrated sensing and communication (ISAC), vehicle-to-everything (V2X) systems, Internet-of-Things (loT) applications, industrial and private networks, defense and aerospace systems, and medical and wearable devices, have become an integral part of modern society.

[0004] In-phase and quadrature signal generation is widely used in radio frequency transceivers, frequency conversion stages, phase-based modulation and demodulation schemes, and other communication and sensing systems. In many applications, a differential in-phase / quadrature (l / Q) generator receives a differential input signal and produces differential outputs corresponding to in-phase components and quadrature components. Phase accuracy, amplitude balance, and loss of the in-phase and quadrature signals can affect overall system performance, including error vector magnitude and image rejection.

[0005] Traditional l / Q generators have been implemented using passive coupler structures, such as transformer-based (or “TF-based”) couplers and coupled-line couplers. A TF-based differential coupler can be formed using patternedAttorney Docket No. EMTAR8003WO PATENTconductive loops and interconnects in one or more metallization layers. Coupled-line couplers can be formed using adjacent conductive traces that exchange energy through electromagnetic coupling and can be used to generate phase-shifted signals and distribute signals among ports.

[0006] To extend bandwidth, designers have employed multi-stage implementations in which multiple coupler stages are cascaded or combined. In some traditional approaches, extending a design to additional stages can be accomplished by replicating a complete coupler block and connecting stages using inter-stage routing. However, traditional multi-stage l / Q generator implementations can present drawbacks. Replicating full coupler blocks for additional stages can increase layout area, which can be difficult to accommodate in area-constrained integrated circuits. Inter-stage routing between separately placed coupler blocks can add conductive path length and parasitic effects, which can degrade insertion loss, phase accuracy, and amplitude balance, and increase sensitivity to process, voltage, and temperature variations. Conventional coupler layouts can also introduce asymmetries between differential paths due to routing constraints and non-uniform electromagnetic environments, which can contribute to phase and amplitude mismatch and require additional layout iterations and tuning.

[0007] Consequently, there remains a need for improved techniques for generating wideband differential in-phase and quadrature signals in integrated circuit implementations.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] One or more embodiments of the present disclosure are illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, in which like references indicate similar elements. These drawings are not necessarily drawn to scale.

[0009] FIG. 1 A illustrates a plan view of an example transformer (TF)-based in-phase / quadrature (l / Q) generation core implemented using concentrically arranged conductive loop segments.

[0010] FIG. 1 B illustrates a corresponding functional block diagram of the TF-based l / Q generation core of FIG. 1 A.Attorney Docket No. EMTAR8003WO PATENT

[0011] FIG. 2 illustrates a functional block diagram of an example multi-stage l / Q generator architecture implemented by cascading multiple TF-based l / Q generator blocks of FIG. 1 B.

[0012] FIG. 3A illustrates a plan view of another example TF-based l / Q generation core with improved symmetry.

[0013] FIG. 3B illustrates a corresponding functional block diagram of the TF-based l / Q generation core of FIG. 3A.

[0014] FIG. 3C illustrates a schematic diagram of an example coupled-line differential coupler.

[0015] FIG. 3D illustrates perspective views of example coupled-line conductive trace structures for implementing a coupled-line differential coupler.

[0016] FIG. 3E illustrates a functional block diagram of an example coupled-line differential coupler-based l / Q generator that can be used as one or more subsequent stages to a TF-based core generator, in accordance with some embodiments.

[0017] FIG. 4 illustrates a functional block diagram of an example two-stage l / Q generator in which a core stage l / Q generation core is coupled to a subsequent coupled-line differential coupler stage.

[0018] FIG. 5A illustrates a plan view of an example layout of a two-stage l / Q generator including an l / Q generation core and a first coupled-line differential coupler stage disposed around the l / Q generation core in the same metal layer.

[0019] FIG. 5B illustrates a plan view of an example layout of a two-stage l / Q generator in which portions of the first coupled-line differential coupler stage are implemented vertically stacked in different metal layers.

[0020] FIG. 6A illustrates a plan view of an example layout of a two-stage l / Q generator similar to FIG. 5A and further including one or more grounded isolation conductors.

[0021] FIG. 6B illustrates a plan view of an example layout of a two-stage l / Q generator similar to FIG. 5B and further including one or more grounded isolation conductors.

[0022] FIG. 7A illustrates a plan view of an example layout of a three-stage l / Q generator including an l / Q generation core, a first coupled-line differential coupler stage, and a second coupled-line differential coupler stage, where outputs from theAttorney Docket No. EMTAR8003WO PATENTfirst coupled-line differential coupler stage are combined and fed into the second coupled-line differential coupler stage.

[0023] FIG. 7B illustrates a functional block diagram and interconnection scheme corresponding to the example three-stage l / Q generator of FIG. 7A.

[0024] FIG. 8A illustrates a plan view of another example layout of a three-stage l / Q generator including an l / Q generation core, a first coupled-line differential coupler stage, and a second coupled-line differential coupler stage, where outputs from the first coupled-line differential coupler stage are fed separately into the second coupled-line differential coupler stage.

[0025] FIG. 8B illustrates a functional block diagram and interconnection scheme corresponding to the example three-stage l / Q generator of FIG. 8A.

[0026] FIG. 9 illustrates an example physical layout of an l / Q generator and includes example overall footprint dimensions.DETAILED DESCRIPTION

[0027] In many radio frequency (RF) integrated circuit (IC) implementations, it is desirable to generate differential in-phase and quadrature signals from a differential input while meeting target specifications for phase balance, amplitude balance, insertion loss, and operational bandwidth. These specifications can be difficult to satisfy in practice because the physical layout of passive coupler structures and the routing of differential signals influence electromagnetic coupling, parasitic capacitance, and parasitic inductance. Accordingly, the achievable performance of an in-phase / quadrature (l / Q) generator is often constrained not only by circuit topology but also by the manner in which the topology is realized in metallization layers of an integrated circuit.

[0028] As described above, conventional in-phase and quadrature signal generation techniques often rely on passive coupler structures that are extended to wider bandwidths by cascading additional stages through replication of full coupler blocks and the use of inter-stage routing. In a number of implementations, replicating complete coupler blocks increases layout area, and the inter-stage routing between separately placed blocks introduces additional conductive path length and parasitic effects.Attorney Docket No. EMTAR8003WO PATENT

[0029] More specifically, in some conventional approaches, bandwidth is improved by cascading multiple couplers having different coupling characteristics. For example, a multi-coupler cascade can be implemented using distributed transmission-line sections between couplers to achieve target phase relationships and impedance transformations across frequency. However, in a number of such implementations, the design uses quarter-wavelength sections at a design frequency, which can occupy substantial physical length on an integrated circuit and therefore increases the overall layout area. Moreover, when multiple quarterwavelength sections are used to interconnect multiple couplers, the cumulative routing length and associated spacing requirements can further increase the area and complicate layout integration. These factors can make it difficult to scale to additional stages while maintaining phase accuracy and amplitude balance between differential signal paths, and can increase design complexity in area-constrained integrated circuit layouts.

[0030] Introduced here, therefore, are techniques that can be used to implement a hybrid differential l / Q generator in which a transformer (TF)-based differential coupler serves as an l / Q generation core and one or more coupled-line differential coupler stages are disposed around the l / Q generation core within a core footprint region. In a number of embodiments, the coupled-line differential coupler stages can be arranged as successive outer-ring conductive structures that surround the conductive loop segments implementing the TF-based differential coupler, and can be conductively coupled to prior stages to support two-stage, three-stage, or N-stage implementations without duplicating additional TF-based differential couplers. Furthermore, in various implementations, the coupled-line differential coupler stages can be implemented coplanar within a metallization layer or can be implemented using vertically stacked metallization layers, and can include grounded isolation conductors disposed between differential conductive traces. In some embodiments, a subsequently added coupled-line differential coupler stage can be configured to receive differential outputs from a prior coupled-line differential coupler stage through a combining network that provides combined differential in-phase and combined differential quadrature signals. In some other embodiments, the subsequently added coupled-line differential coupler stage can be configured to receive differentialAttorney Docket No. EMTAR8003WO PATENToutputs from the prior coupled-line differential coupler stage through separate signal paths using multiple coupled-line couplers.

[0031] Overall, the embodiments of the present disclosure can provide a scalable l / Q generator architecture that can be extended to additional stages through layout-driven reuse of a common TF-based differential coupler that serves as the l / Q generation core and the addition of outer coupled-line stages. By reducing reliance on replicated standalone TF-based differential coupler blocks and by controlling inter-stage coupling through compact conductive structures disposed around the core, the disclosed approaches can support improved integration in area-constrained layouts and can facilitate maintaining differential symmetry and balanced phase relationships as additional stages are added. In a number of embodiments, implementing coupled-line stages coplanar or vertically stacked and employing grounded isolation conductors can further support design flexibility while managing electromagnetic interactions between adjacent differential traces.

[0032] In the following, numerous specific details are set forth to provide a thorough understanding of the presently disclosed techniques. In other embodiments, the techniques introduced here can be practiced without these specific details. In other instances, well-known features, such as specific fabrication techniques, are not described in detail in order to avoid unnecessarily obscuring the present disclosure. References in this description to “an embodiment,” “one embodiment,” or the like, mean that a particular feature, structure, material, or characteristic being described is included in at least one embodiment of the present disclosure. Thus, the appearances of such phrases in this specification do not necessarily all refer to the same embodiment. On the other hand, such references are not necessarily mutually exclusive either. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments. Also, it is to be understood that the various embodiments shown in the figures are merely illustrative representations and are not necessarily drawn to scale.

[0033] Certain details relating to structures or processes commonly associated with the integrated circuit design, including physical layouts of certain typical components, e.g., inductors, capacitors, resistors, filters, and related subcomponents, may not be set forth in the following description, as inclusion ofAttorney Docket No. EMTAR8003WO PATENTsuch well-known details could obscure significant aspects of the disclosed techniques. Moreover, although the following disclosure sets forth several embodiments of different aspects of the present disclosure, several other embodiments can have different configurations or different components than those described in this section. Accordingly, the introduced techniques can have other embodiments with additional elements or without several of the elements described below.

[0034] For purposes of discussion here, the terms “coupled” and “connected,” along with their derivatives, can be used to describe structural relationships between components. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” can be used to indicate that two or more elements are in direct contact with each other. Unless otherwise made apparent in the context, the term “coupled” can be used to indicate that two or more elements are in either direct or indirect (with other intervening elements between them) contact with each other, or that the two or more elements co-operate or interact with each other (e.g., as in a cause and effect relationship), or both. Notwithstanding the above, and unless otherwise specified or made clear by the context, references to components being “connected in series” or “connected in parallel” refer to their functional electrical relationship rather than requiring uninterrupted physical conductors.

[0035] For purposes of discussion here, the terms “plan view,” “viewed in plan,” “top view,” and “top plan view,” or wording to the equivalent, refer to a view of an integrated circuit layout projected onto a plane parallel to the surface of the semiconductor wafer, without regard to the vertical positions of elements on different metal layers. In such a view, elements disposed on different layers may appear to overlap or coincide, even though they can be physically separated in the vertical direction.

[0036] For purposes of discussion here, the terms “vertical” and “horizontal” are defined with respect to the surface of a semiconductor wafer on which an integrated circuit is fabricated. A vertical direction refers generally to a direction normal (or perpendicular) to the plane of the wafer, while a horizontal direction refers generally to a direction parallel to the plane of the wafer.Attorney Docket No. EMTAR8003WO PATENT

[0037] For purposes of discussion here, the term “primarily,” when used to describe the disposition of a component on a particular layer or in a particular orientation, means that a larger portion of the component is disposed on that layer or in that orientation than on any other single layer or orientation, even if less than a majority of the component is so disposed.

[0038] For purposes of discussion here, “vertical stacking” refers to implementing conductive traces on different metal layers separated by one or more interlayer dielectric regions, where at least portions of the conductive traces overlap in plan view.

[0039] For purposes of discussion here, a “core footprint region” refers to a plan-view region of the conductive layout occupied by an l / Q generation core that includes a TF-based differential coupler. An “outer-ring conductive structure” refers to a conductive structure of a coupled-line differential coupler stage that surrounds, in plan view, at least a portion of a conductive structure of a prior stage within a footprint region that includes the core footprint region.

[0040] For purposes of discussion here, “shape symmetry,” in the context of describing a property of differential couplers, refers to the correspondence, about a reference axis, between geometric shapes of conductive routing on a first differential side and geometric shapes of conductive routing on a second differential side. In practical examples, the correspondence in geometric shapes can be assessed based on whether a first conductive trace on the first differential side and a second conductive trace on the second differential side have substantially mirror-symmetric shapes in plan view, including corresponding bends, turns, curvature, and relative positioning along a signal path.

[0041] For purposes of discussion here, “length symmetry,” in the context of describing a property of differential couplers, refers to the correspondence between conductive path lengths on a first differential side and conductive path lengths on a second differential side, measured between corresponding nodes along corresponding signal paths. Note that conductive path lengths can be considered length-symmetric when a difference is within a reasonable tolerance (e.g., associated with fabrication process variations and layout quantization).

[0042] FIG. 1 A illustrates a plan view of an example TF-based l / Q generation core 100 implemented as a conductive layout on a substrate. The TF-based l / QAttorney Docket No. EMTAR8003WO PATENTgeneration core 100 includes a plurality of concentrically arranged conductive loop segments that are configured to provide transformer action through magnetic coupling among the loop segments.

[0043] As shown in FIG. 1 A, the TF-based l / Q generation core 100 includes a first differential input port having a first input node (ln / 0) and a second input node ( I n / 180). The TF-based l / Q generation core 100 further includes a first differential in-phase output port having a first in-phase output node (Out / O) and a second in-phase output node (Out / 180), and a first differential quadrature output port having a first quadrature output node (Out / 90) and a second quadrature output node (Out / 270). In operation, the TF-based l / Q generation core 100 can receive a differential input signal at the first differential input port and, through electromagnetic coupling provided by the concentrically arranged conductive loop segments, generate (i) a differential output corresponding to an in-phase component (e.g., Out / O and Out / 180) and (ii) a differential output corresponding to a quadrature component (e.g., Out / 90 and Out / 270) that is in quadrature with the in-phase component. The TF-based l / Q generation core 100 also includes isolation nodes (labeled Isolation) that can be used as isolated ports.

[0044] In various implementations, the TF-based l / Q generation core can include conductive interconnect segments (e.g., bridge connections and crossover connections) disposed between or among the concentrically arranged conductive loop segments, or other suitable layout features configured to adjust coupling and balance of the TF-based l / Q generation core for a target operating frequency range. For example, such conductive interconnect segments can be placed at selected locations along the conductive loop segments to adjust effective coupling between differential sides and to manage symmetry between signal paths, depending on layout constraints and desired electrical characteristics.

[0045] Note that, in the illustrated example, the conductive loop segments have a generally rectilinear shape in plan view. However, in some implementations, TF-based couplers can be implemented using conductive loop segments having generally octagonal shapes in plan view, and other polygonal or rounded geometries can also be used, depending on layout constraints, routing objectives, and desired coupling characteristics.Attorney Docket No. EMTAR8003WO PATENT

[0046] Also note that, although the present disclosure describes a number of embodiments in which an l / Q generation core is implemented as a TF-based differential coupler, this description is provided for purposes of illustration and explanation and is not intended to be limiting. The techniques disclosed here for implementing one or more coupled-line differential coupler stages as conductive structures disposed around an l / Q generation core within a footprint region (including the core footprint region) can be similarly applicable to, or adapted for use with, other suitable types of differential couplers or l / Q generation cores, depending on target specifications and layout constraints of a given integrated circuit implementation.

[0047] FIG. 1 B illustrates a corresponding functional block diagram 105 of the TF-based l / Q generation core 100 of FIG. 1 A. As shown in FIG. 1 B, the TF-based l / Q generation core 100 receives the differential input signal at ln / 0 and ln / 180, and provides the differential in-phase output at Out / O and Out / 180 and the differential quadrature output at Qut / 90 and Qut / 270. The isolation ports shown in FIG. 1 B correspond to the isolation nodes labeled Isolation in FIG. 1 A, and in some embodiments, can be coupled to suitable terminations to improve isolation.

[0048] FIG. 2 illustrates a functional block diagram of an example multi-stage l / Q generator architecture 200 implemented by cascading multiple TF-based l / Q generator blocks (e.g., TF-based l / Q generation cores as described with respect to FIG. 1 B). In the illustrated example, a first TF-based l / Q generator block receives a differential input signal at a first input node (ln / 0) and a second input node (ln / 180). In response to the differential input signal, the first TF-based l / Q generator block generates a first differential in-phase output (corresponding to 0° and 180° components) and a first differential quadrature output (corresponding to 90° and 270° components). The first TF-based l / Q generator block further includes isolation ports (labeled Isolation) that can be coupled to suitable terminations in particular implementations.

[0049] As further shown in FIG. 2, one or more differential outputs from the first TF-based l / Q generator block are routed, via interconnection conductors, to provide differential inputs to one or more subsequent TF-based l / Q generator blocks. In the illustrated example, two additional TF-based l / Q generator blocks can be coupled to the first TF-based l / Q generator block through respective interconnection paths, such that the TF-based l / Q generator blocks are cascaded to form the multiAttorney Docket No. EMTAR8003WO PATENTstage l / Q generator architecture 200. The interconnection paths can include differential interconnect segments that are arranged to preserve differential pairing and to provide phase matching between corresponding paths.

[0050] In operation, the cascaded TF-based l / Q generator blocks of FIG. 2 can be configured to provide wider operational bandwidth than a single TF-based l / Q generation core operating alone, for example by distributing coupling and phase response across multiple stages. However, the cascade configuration can require phase-matching interconnection lines between stages. In integrated circuit implementations, these interconnection lines can be relatively long and can introduce conductor loss and parasitic effects, and the cumulative routing length and spacing requirements can occupy additional layout area. These drawbacks motivate the improved techniques introduced here for implementing l / Q generators where a TF-based l / Q generation core can be integrated with one or more additional stages within a shared footprint region, thereby reducing reliance on long phase-matching interconnection lines between cascaded TF-based blocks.

[0051] FIG. 3A illustrates a plan view of another example TF-based l / Q generation core 300 implemented as a conductive layout on a substrate. The TF-based l / Q generation core 300 can be generally similar to the TF-based l / Q generation core 100 of FIG. 1 A, but includes additional conductive interconnect segments that are arranged to provide improved symmetry in the conductive routing of the TF-based differential coupler.

[0052] As shown in FIG. 3A, the TF-based l / Q generation core 300 includes a first differential input port having a first input node (ln / 0) and a second input node ( I n / 180). The TF-based l / Q generation core 300 further includes a first differential in-phase output port having a first in-phase output node (Out / O) and a second in-phase output node (Out / 180), and a first differential quadrature output port having a first quadrature output node (Qut / 90) and a second quadrature output node (Qut / 270). The TF-based l / Q generation core 300 also includes isolation nodes (labeled Isolation) that can be used as isolated ports for the TF-based l / Q generation core 300. In operation, similar to the TF-based l / Q generation core 100 in FIG. 1 A, the TF-based l / Q generation core 300 can receive a differential input signal at the first differential input port and, through electromagnetic coupling provided by the concentrically arranged conductive loop segments, generate (i) a differential inAttorney Docket No. EMTAR8003WO PATENTphase output and (ii) a differential quadrature output that is in quadrature with the differential in-phase output.

[0053] In the illustrated example of FIG. 1 A, the TF-based l / Q generation core 100 includes an innermost conductive loop and at least one additional conductive loop surrounding the innermost conductive loop. It is recognized in the present disclosure that, in the layout shown in FIG. 1 A, the conductive trace for the innermost conductive loop can be shorter than a conductive trace for the surrounding conductive loop, and because the conductive-trace length is imbalanced, the geometry of the conductive routing can also be less symmetric than desired. Such length and shape asymmetries can contribute to differential imbalance that can manifest as amplitude mismatch and / or phase mismatch in generated differential outputs.

[0054] To address these effects observed in the example of FIG. 1A, the TF-based l / Q generation core 300 further includes a first bridge 312 and a second bridge 314 that physically connect the innermost conductive loop to an adjacent surrounding conductive loop at respective connection locations along a perimeter of the innermost conductive loop. Further, in some embodiments, the connection locations of the first bridge 312 and the second bridge 314 can be arranged symmetrically about a reference axis (e.g., the centerline shown in FIG. 3A), such that conductive routing on a first differential side and conductive routing on a second differential side exhibit improved shape symmetry and / or length symmetry as compared to implementations without the two bridges. With the bridges 312 and 314, the innermost conductive loop can be electrically and physically coupled to the surrounding conductive loop at two spaced-apart connection locations, which can effectively increase an electrical path length associated with the innermost conductive loop and can reduce a length mismatch relative to the surrounding conductive loop. In some embodiments, because the bridges 312 and 314 are positioned at connection locations that are symmetric about the reference axis, resulting current paths on opposite differential sides can be made more symmetric in both geometry and effective path length, thereby improving shape symmetry and length symmetry of the TF-based differential coupler. By reducing path length and geometric asymmetries between corresponding differential signal paths, the bridges 312 and 314 can reduce differential imbalance that would otherwise contribute toAttorney Docket No. EMTAR8003WO PATENTamplitude mismatch and / or phase mismatch between the generated in-phase and quadrature outputs. In other words, by improving shape symmetry and length symmetry of corresponding conductive routing on opposite differential sides, the TF-based l / Q generation core 300 of FIG. 3A can provide improved amplitude balance and phase balance between differential signal paths as compared to the TF-based l / Q generation core 100 of FIG. 1 A.

[0055] FIG. 3B illustrates a corresponding functional block diagram 305 of the TF-based l / Q generation core 300 of FIG. 3A. As shown in FIG. 3B, the TF-based l / Q generation core 300 receives the differential input signal at ln / 0 and ln / 180, and provides the differential in-phase output at Out / O and Out / 180 and the differential quadrature output at Qut / 90 and Qut / 270. The isolation ports shown in FIG. 3B correspond to the isolation nodes labeled Isolation in FIG. 3A, and in some embodiments, can be coupled to suitable terminations to improve isolation. The TF-based l / Q generation core 300 of FIGS. 3A and 3B can be used as a TF-based l / Q generation core (e.g., as an alternative to the TF-based l / Q generation core 100 of FIGS. 1 A and 1 B, or another suitable l / Q generation core) for subsequent architectures described in this disclosure.

[0056] FIG. 3C illustrates a schematic diagram of an example coupled-line differential coupler 302. Coupled-line directional couplers are fairly commonly adapted planar quadrature signal generation circuits in practice, and FIG. 3C is provided as a reference representation of such a coupled-line differential coupler. In a number of implementations, a coupled-line coupler includes adjacent conductive traces (or transmission-line conductors) arranged to provide electromagnetic coupling over a coupling region.

[0057] In the illustrated example, the coupled-line differential coupler 302 includes an in-phase differential input port having a first input node (ln / 0) and a second input node (ln / 180). The coupled-line differential coupler 302 further includes an in-phase differential output port having a first in-phase output node (Out / O) and a second in-phase output node (Out / 180), and a quadrature differential output port having a first quadrature output node (Qut / 90) and a second quadrature output node (Qut / 270). In such implementations, a differential input signal can be applied at the in-phase differential input port (e.g., ln / 0 and ln / 180), and the coupled-line structure can provide (i) a differential through or in-phase output (e.g., Out / O andAttorney Docket No. EMTAR8003WO PATENTOut / 180) and (ii) a differential quadrature output (e.g., Out / 90 and Out / 270) that is in quadrature with the differential in-phase output.

[0058] In some implementations, the coupled-line coupler can include one or more isolated ports (Iso.) corresponding to a coupled port that is intended to be isolated from the input and / or through ports. In various embodiments, the isolated port can be coupled to a suitable termination (e.g., a matching impedance) to support isolation performance and to reduce undesired reflections. Note that the coupler 302 in FIG. 3C is merely an example; other suitable input / output configures and port arrangements can be used in other implementations.

[0059] FIG. 3D illustrates perspective views of example coupled-line conductive trace structures 304 and 308 for implementing the coupled-line differential coupler 302 of FIG. 3C. In the illustrated example, the coupled-line conductive trace structure 304 corresponds to a coplanar implementation in which the coupled-line traces are primarily implemented in the same metal layer.

[0060] The coupled-line conductive trace structure 308 corresponds to a vertically stacked implementation in which portions of the coupled-line traces are primarily implemented in different metal layers and overlap, in plan view, over at least a portion of a coupling region while being separated by one or more interlayer dielectric regions. In various implementations, the coupled-line geometry (e.g., trace width, trace spacing, coupling length, overlap length, and layer separation) can be selected to achieve a target coupling and phase response, and isolated nodes associated with the coupled-line structure can be routed to support external terminations and / or test access, as appropriate for a given integrated circuit layout. Further, in some embodiments, multiple metal layers can be used to implement portions of the coupled-line traces.

[0061] FIG. 3E illustrates a functional block diagram of an example coupled-line differential coupler based l / Q generator 350 that can be used as, e.g., a subsequent stage to a TF-based l / Q generation core, in accordance with some embodiments. In the illustrated example, the coupled-line differential coupler based l / Q generator 350 can receive a differential input signal (e.g., an in-phase differential input at ln / 0 and ln / 180) and provide a differential in-phase output (e.g., Out / O and Out / 180) and a differential quadrature output (e.g., Out / 90 and Out / 270). In some embodiments, the l / Q generator 350 can include an in-phase coupled-line couplerAttorney Docket No. EMTAR8003WO PATENTconfigured to receive a differential in-phase signal and a quadrature coupled-line coupler configured to receive a differential quadrature signal, where the differential quadrature signal is in quadrature with the differential in-phase signal. Each coupled-line coupler can provide corresponding differential outputs, and each coupled-line coupler can further include one or more isolated ports (Iso.) that, in some embodiments, can be coupled to suitable terminations to improve isolation.

[0062] The coupled-line differential coupler based l / Q generator 350 is provided here to illustrate that coupled-line differential coupler stages can serve as subsequent stages that are conductively coupled to a TF-based l / Q generation core (e.g., as introduced starting with FIG. 4 and implemented in the layouts starting with FIG. 5A), thereby enabling hybrid multi-stage l / Q generator implementations in which a TF-based core stage provides differential in-phase and quadrature signals that are then processed by one or more coupled-line stages.

[0063] FIG. 4 illustrates a functional block diagram of an example two-stage hybrid differential l / Q generator 400. In the illustrated example, the two-stage l / Q generator 400 includes a core stage l / Q generation core 410 and a subsequent stage 420 that is coupled to the core stage l / Q generation core 410. The l / Q generation core 410 can be implemented as a TF-based differential coupler (e.g., the TF-based l / Q generation core 100 of FIGS. 1 A-1 B, the TF-based l / Q generation core 300 of FIGS. 3A-3B, or another suitable TF-based l / Q generation core).

[0064] As shown in FIG. 4, the core stage l / Q generation core 410 receives a differential input signal at a first input node (ln / 0) and a second input node (ln / 180), and generates (i) a differential in-phase output (Out / O and Qut / 180) and (ii) a differential quadrature output (Qut / 90 and Qut / 270) that is in quadrature with the differential in-phase output. The l / Q generation core 410 also includes isolation ports (Iso.) that correspond to isolated ports of the TF-based differential coupler.

[0065] The subsequent stage 420 of the two-stage l / Q generator 400 includes an in-phase coupled-line coupler 420(1 ) and a quadrature coupled-line coupler 420(2). The in-phase coupled-line coupler 420(1) is configured to receive a first differential signal from the l / Q generation core 410, such as a differential signal from the differential in-phase output provided at Out / O and Qut / 180, and to provide a differential in-phase and quadrature output at the second stage. The quadrature coupled-line coupler 420(2) is configured to receive a second differential signal fromAttorney Docket No. EMTAR8003WO PATENTthe l / Q generation core 410, such as a differential signal from the differential quadrature output provided at Out / 90 and Out / 270, and to provide a differential in-phase and quadrature output at the second stage. Each of the coupled-line couplers 420(1) and 420(2) can also include one or more isolation ports (Iso.).

[0066] In addition, in some embodiments, the l / Q generation core 410 can be configured for operation at a first center frequency f1 , and the in-phase coupled-line coupler 420(1 ) and the quadrature coupled-line coupler 420(2) can be configured for operation at a second center frequency f2 that is different from the first center frequency f1. For example, the second center frequency f2 can be selected such that a frequency response associated with the subsequent stage 420 overlaps a frequency response associated with the l / Q generation core 410, thereby providing an operational bandwidth that is wider than the bandwidth of the l / Q generation core 410 alone. Nevertheless, in some other embodiments, the second center frequency f2 can be the same as the first center frequency f1.

[0067] As further shown in FIG. 4, the subsequent stage 420 can be coupled to the core stage l / Q generation core 410 through differential interconnection conductors that preserve differential pairing between corresponding nodes. In some embodiments, the interconnection conductors can be arranged to support phase matching between corresponding differential paths and to reduce discontinuities between coupled stages.

[0068] FIG. 5A illustrates a plan view of an example physical layout of a two-stage l / Q generator 500 formed as a conductive layout on a substrate. The two-stage l / Q generator 500 includes an l / Q generation core 510 and a first coupled-line differential coupler stage 520 disposed around the l / Q generation core 510. In the illustrated example, the l / Q generation core 510 is implemented as a TF-based differential coupler using a plurality of concentrically arranged conductive loop segments, e.g., as described above with respect to FIGS. 1 A-1B and FIGS. 3A-3B. In the illustrated example, the first coupled-line differential coupler stage is implemented within a footprint region that includes the core footprint region such that conductive structures of the first coupled-line differential coupler stage are disposed around the l / Q generation core while occupying the same general plan-view region as the l / Q generation core.Attorney Docket No. EMTAR8003WO PATENT

[0069] As shown, the first coupled-line differential coupler stage 520 surrounds, in plan view, at least a portion of the conductive loop segments implementing the l / Q generation core 510, such that the first coupled-line differential coupler stage 520 is disposed around the l / Q generation core 510 within a footprint region that includes the core footprint region. In the embodiment in FIG. 5A, the first coupled-line differential coupler stage 520 includes an in-phase coupled-line coupler 520(1 ) and a quadrature coupled-line coupler 520(2). The in-phase coupled-line coupler 520(1) and the quadrature coupled-line coupler 520(2) are formed as conductive trace structures that extend around the l / Q generation core 510 and are arranged as an outer-ring conductive structure relative to the conductive loop segments of the l / Q generation core 510. In accordance with some of the present embodiments, the in-phase coupled-line coupler and the quadrature coupled-line coupler can be implemented using conductive loop segments arranged as one or more outer loops that surround the concentrically arranged conductive loop segments of the TF-based differential coupler. In a number of embodiments, the in-phase coupled-line coupler 520(1) and the quadrature coupled-line coupler 520(2) are arranged symmetrically about a centerline of the core footprint region.

[0070] The l / Q generation core 510 includes a first differential input port having a first input node (ln / 0) and a second input node (ln / 180). The l / Q generation core 510 further includes a first differential in-phase output port having a first in-phase output node (Out / O) and a second in-phase output node (Qut / 180), and a first differential quadrature output port having a first quadrature output node (Qut / 90) and a second quadrature output node (Qut / 270). In the illustrated implementation, conductive interconnect segments route the differential in-phase outputs (Out / O and Qut / 180) from the l / Q generation core 510 to the in-phase coupled-line coupler 520(1), and route the differential quadrature outputs (Qut / 90 and Qut / 270) from the l / Q generation core 510 to the quadrature coupled-line coupler 520(2). Then, the in-phase coupled-line coupler 520(1) and the quadrature coupled-line coupler 520(2) provide corresponding differential outputs that can be taken from output nodes located toward the periphery of the layout, as shown in FIG. 5A (e.g., Out / O and Qut / 180 on a first side, and Qut / 90 and Qut / 270 on a second side). Further, illustrated in FIG. 5A are isolation nodes (labeled Isolation) associated with the coupled-line structures. In some embodiments, these isolation nodes can be usedAttorney Docket No. EMTAR8003WO PATENTas isolated ports of one or more coupled-line couplers and, in particular implementations, can be coupled to suitable terminations to improve isolation. In some embodiments, each of the in-phase coupled-line coupler and the quadrature coupled-line coupler includes a respective pair of isolation ports.

[0071] In the example of FIG. 5A, the in-phase coupled-line coupler 520(1 ) and the quadrature coupled-line coupler 520(2) are implemented coplanar, such that conductive traces implementing the in-phase coupled-line coupler 520(1) and conductive traces implementing the quadrature coupled-line coupler 520(2) are primarily implemented in a same metal layer. Implementing the coupled-line differential coupler stage 520 as an outer-ring conductive structure around the l / Q generation core 510 can reduce reliance on long phase-matching interconnection lines between separately placed coupler blocks, because the second stage is integrated in close physical proximity to the TF-based l / Q generation core 510. In addition, arranging the in-phase coupled-line coupler 520(1) and the quadrature coupled-line coupler 520(2) around the l / Q generation core 510 can facilitate maintaining routing symmetry between corresponding differential signal paths, which can support amplitude balance and phase balance in the generated differential outputs.

[0072] FIG. 5B illustrates a plan view of another example physical layout of a two-stage l / Q generator 505 formed as a conductive layout on a substrate. The two-stage l / Q generator 505 can be generally similar to the two-stage l / Q generator 500 of FIG. 5A, and includes an l / Q generation core 515 and a first coupled-line differential coupler stage 525 disposed around the l / Q generation core 515. The l / Q generation core 515 can be implemented as a TF-based differential coupler using a plurality of concentrically arranged conductive loop segments, e.g., as described above with respect to FIGS. 1 A-1 B and FIGS. 3A-3B.

[0073] As shown in FIG. 5B, the first coupled-line differential coupler stage is implemented within a footprint region that includes the core footprint region such that conductive structures of the first coupled-line differential coupler stage are disposed around the l / Q generation core while occupying the same general plan-view region as the l / Q generation core. In the illustrated implementation, the first coupled-line differential coupler stage 525 is integrated in close physical proximity to the l / Q generation core 515, such that the second stage is implemented as conductiveAttorney Docket No. EMTAR8003WO PATENTstructures that extend around the TF-based conductive loop segments of the l / Q generation core 515 rather than as a separately placed coupler block.

[0074] In the embodiment illustrated in FIG. 5B, the first coupled-line differential coupler stage 525 surrounds, in plan view, at least a portion of the conductive loop segments implementing the l / Q generation core 515, such that the first coupled-line differential coupler stage 525 is disposed around the l / Q generation core 515 within a footprint region that includes the core footprint region. The first coupled-line differential coupler stage 525 includes an in-phase coupled-line coupler 525(1 ) and a quadrature coupled-line coupler 525(2). The in-phase coupled-line coupler 525(1) and the quadrature coupled-line coupler 525(2) can be formed as conductive trace structures that extend around the l / Q generation core 515 and are arranged as an outer-ring conductive structure relative to the conductive loop segments of the l / Q generation core 515. In accordance with some of the present embodiments, the in-phase coupled-line coupler and the quadrature coupled-line coupler can be implemented using conductive loop segments arranged as one or more outer loops that surround the concentrically arranged conductive loop segments of the TF-based differential coupler. In a number of embodiments, the in-phase coupled-line coupler 525(1) and the quadrature coupled-line coupler 525(2) are arranged symmetrically about a centerline of the core footprint region. In comparison to FIG. 5A, FIG. 5B illustrates an implementation in which portions of the in-phase coupled-line coupler 525(1) and portions of the quadrature coupled-line coupler 525(2) are implemented using different metal layers and are vertically stacked.

[0075] More specifically, in one or more embodiments, the in-phase coupled-line coupler 525(1) can be primarily implemented in a first metal layer and the quadrature coupled-line coupler 525(2) can be primarily implemented in a second metal layer that is different from the first metal layer. The first metal layer and the second metal layer can be separated by, e.g., one or more interlayer dielectric regions. Further, in a plan view of the substrate (e.g., as shown in FIG. 5B), at least a portion of the in-phase coupled-line coupler 525(1 ) can vertically overlap at least a portion of the quadrature coupled-line coupler 525(2), even though the overlapping portions are disposed on different metal layers. Such vertical overlap can enable the first coupled-line differential coupler stage 525 to occupy a reduced planar footprintAttorney Docket No. EMTAR8003WO PATENTrelative to a fully coplanar implementation, because at least some conductive traces associated with one coupled-line coupler can be routed over or under conductive traces associated with the other coupled-line coupler. In some embodiments, the extent and location of vertical overlap between the in-phase coupled-line coupler 525(1) and the quadrature coupled-line coupler 525(2) can be selected to satisfy layout-density constraints while maintaining desired coupling characteristics for the coupled-line structures.

[0076] Further, the l / Q generation core 515 includes a first differential input port having a first input node (ln / 0) and a second input node (ln / 180). The l / Q generation core 515 further includes a first differential in-phase output port having a first in-phase output node (Out / O) and a second in-phase output node (Out / 180), and a first differential quadrature output port having a first quadrature output node (Out / 90) and a second quadrature output node (Out / 270). Conductive interconnect segments route the differential in-phase outputs (Out / O and Out / 180) from the l / Q generation core 515 to the in-phase coupled-line coupler 525(1), and route the differential quadrature outputs (Out / 90 and Out / 270) from the l / Q generation core 515 to the quadrature coupled-line coupler 525(2). Then, the in-phase coupled-line coupler 525(1) and the quadrature coupled-line coupler 525(2) provide corresponding differential in-phase and quadrature outputs that can be taken from output nodes located toward the periphery of the layout, as shown. In various implementations, the conductive interconnect segments can be arranged to preserve differential pairing and to provide phase matching between corresponding differential paths between the l / Q generation core 515 and the coupled-line structures of the first coupled-line differential coupler stage 525.

[0077] The two-stage l / Q generator 505 also includes a number of isolation nodes (labeled Isolation) associated with the coupled-line structures. In some embodiments, the isolation nodes can be used as isolated ports of one or more coupled-line couplers and, in particular implementations, can be coupled to suitable terminations to improve isolation. In some embodiments, each of the in-phase coupled-line coupler and the quadrature coupled-line coupler includes a respective pair of isolation ports. In some embodiments, the routing of isolation nodes and associated access traces can be selected to reduce unwanted coupling to adjacentAttorney Docket No. EMTAR8003WO PATENTdifferential traces while maintaining connectivity to external terminations or test structures.

[0078] In one or more embodiments, implementing portions of the first coupled-line differential coupler stage 525 using vertically stacked metal layers can provide additional routing flexibility as compared to a fully coplanar implementation. For example, vertical stacking can facilitate routing the coupled-line structures around the l / Q generation core 515 while maintaining differential pairing and managing layout density in the footprint region that includes the core footprint region. Further, because at least some conductive traces overlap in plan view while being separated by an interlayer dielectric, the degree of electromagnetic coupling between vertically adjacent traces can be managed through selection of layer spacing and trace geometry in particular implementations.

[0079] FIG. 6A illustrates a plan view of an example physical layout of a two-stage l / Q generator 600 formed as a conductive layout on a substrate. The two-stage l / Q generator 600 can be generally similar to the two-stage l / Q generator 500 of FIG. 5A, and includes an l / Q generation core (implemented as a TF-based differential coupler using concentrically arranged conductive loop segments) and a first coupled-line differential coupler stage disposed around the l / Q generation core within a footprint region that includes the core footprint region. In the illustrated implementation, the first coupled-line differential coupler stage includes an in-phase coupled-line coupler and a quadrature coupled-line coupler that are implemented coplanar, and conductive interconnect segments route differential in-phase outputs of the l / Q generation core to the in-phase coupled-line coupler and route differential quadrature outputs of the l / Q generation core to the quadrature coupled-line coupler.

[0080] In addition to the structures described with respect to FIG. 5A, FIG. 6A further illustrates one or more grounded isolation conductors 640 and 642. In one or more embodiments, the grounded isolation conductors 640 and 642 are conductive traces that are electrically coupled to a ground reference (e.g., through one or more vias or other ground connections, not shown for simplicity) and disposed between conductive traces that carry differential signals in the first coupled-line differential coupler stage. For example, a grounded isolation conductor can be disposed between differential conductive traces of the in-phase coupled-line coupler and / or between differential conductive traces of the quadrature coupled-line coupler, andAttorney Docket No. EMTAR8003WO PATENTcan extend along at least a portion of a length of the corresponding coupled-line structure. In this manner, the grounded isolation conductors 640 and 642 can provide an electromagnetic shielding effect that can reduce undesired coupling (e.g., crosstalk) between adjacent differential traces and can improve isolation in the two-stage l / Q generator 600. In some embodiments, inclusion of grounded isolation conductors can slightly increase layout real estate (e.g., by consuming routing space and / or increasing spacing between traces), and the placement and geometry of the grounded isolation conductors can be selected to balance isolation improvement with layout density and coupling targets for the coupled-line structures.

[0081] FIG. 6B illustrates a plan view of another example physical layout of a two-stage l / Q generator 605 formed as a conductive layout on a substrate. The two-stage l / Q generator 605 can be generally similar to the two-stage l / Q generator 505 of FIG. 5B, in that portions of the first coupled-line differential coupler stage can be implemented using different metal layers and can be vertically stacked, including implementations in which at least portions of an in-phase coupled-line coupler and a quadrature coupled-line coupler overlap in plan view while being separated by one or more interlayer dielectric regions. Similar to FIG. 6A, FIG. 6B further illustrates one or more grounded isolation conductors 645 and 647.

[0082] In one or more embodiments, the grounded isolation conductors 645 and 647 are disposed between one or more pairs of conductive traces that carry differential signals, including between differential conductive traces of the in-phase coupled-line coupler and / or between differential conductive traces of the quadrature coupled-line coupler. In vertically stacked implementations, grounded isolation conductors can be provided in a same metal layer as a corresponding coupled-line structure and / or in a different metal layer than the coupled-line structure, depending on routing objectives and isolation targets. For example, a grounded isolation conductor can be routed along a length of a coupled-line structure to reduce undesired coupling between adjacent differential traces, while the degree of intended electromagnetic coupling in the coupled-line structures can be maintained through selection of trace geometry, spacing, and layer separation. As noted above, grounded isolation conductors can enhance isolation with a slight compromise in layout real estate, and other grounded isolation configurations can also be utilized in place of (or in addition to) a simple grounded line between differential conductiveAttorney Docket No. EMTAR8003WO PATENTtraces (e.g., multiple grounded guard traces, grounded shielding patterns, or other grounded isolation structures), depending on isolation requirements and layout constraints.

[0083] FIG. 7A illustrates a plan view of an example physical layout of a three-stage l / Q generator 700 formed as a conductive layout on a substrate. The three-stage l / Q generator 700 includes an l / Q generation core 710, a first coupled-line differential coupler stage 720 disposed around the l / Q generation core 710, and a second coupled-line differential coupler stage 730 disposed around the first coupled-line differential coupler stage 720 within a footprint region that includes a core footprint region. In the illustrated implementation, the l / Q generation core 710 is implemented as a TF-based differential coupler using a plurality of concentrically arranged conductive loop segments (e.g., as described above with respect to FIGS.1 A-1 B and FIGS. 3A-3B). The first coupled-line differential coupler stage 720 and the second coupled-line differential coupler stage 730 can each be implemented as respective outer-ring conductive structures relative to the TF-based conductive loop segments of the l / Q generation core 710, such that successive coupled-line stages are integrated in close physical proximity to the l / Q generation core 710 rather than being implemented as separately placed coupler blocks connected by long phasematching interconnections.

[0084] In the example of FIG. 7A, the first coupled-line differential coupler stage 720 includes a first-stage in-phase coupled-line coupler and a first-stage quadrature coupled-line coupler arranged around the l / Q generation core 710.Conductive interconnect segments are implemented to route differential in-phase outputs produced by the l / Q generation core 710 to the first-stage in-phase coupled-line coupler, and to route differential quadrature outputs produced by the l / Q generation core 710 to the first-stage quadrature coupled-line coupler. The first coupled-line differential coupler stage 720 provides differential outputs that include a differential in-phase output and a differential quadrature output, and in some implementations can further provide additional differential components (e.g., a differential quadrature component on the in-phase side and a differential in-phase component on the quadrature side) that are used for inter-stage combining as described below. FIG. 7A also illustrates isolation nodes (labeled Isolation) associated with one or more coupled-line structures, which can be used as isolatedAttorney Docket No. EMTAR8003WO PATENTports and, in particular implementations, can be coupled to suitable terminations to improve isolation. Additionally, in some embodiments, the first coupled-line differential coupler stage 720 and / or the second coupled-line differential coupler stage 730 can further include one or more grounded isolation conductors (e.g., as described with respect to FIGS. 6A-6B) disposed between differential conductive traces to improve isolation.

[0085] In the example shown in FIG. 7A, outputs from the first coupled-line differential coupler stage 720 are combined and fed into the second coupled-line differential coupler stage 730. More specifically, in one or more embodiments, a combining network is implemented by conductive interconnect segments that (i) combine a differential in-phase output provided by the first-stage in-phase coupled-line coupler with a differential in-phase component provided by the first-stage quadrature coupled-line coupler to form a combined differential in-phase signal, and (ii) combine a differential quadrature output provided by the first-stage quadrature coupled-line coupler with a differential quadrature component provided by the first-stage in-phase coupled-line coupler to form a combined differential quadrature signal. The second coupled-line differential coupler stage 730 can include a second-stage in-phase coupled-line coupler and a second-stage quadrature coupled-line coupler that receive, as respective differential inputs, the combined differential in-phase signal and the combined differential quadrature signal. The second coupled-line differential coupler stage 730 can then generate a second-stage set of differential outputs that include an in-phase component (e.g., corresponding to 0° and 180° components) and a quadrature component (e.g., corresponding to 90° and 270° components). In a number of embodiments, the second coupled-line differential coupler stage 730 can be implemented as a second outer-ring conductive structure surrounding the conductive structures of the first coupled-line differential coupler stage 720, thereby extending the architecture to additional stages through layout-driven addition of outer coupled-line structures around a common TF-based l / Q generation core 710.

[0086] More specifically, it is recognized in the present disclosure that implementing the combined-input feed to the second coupled-line differential coupler stage 730 can represent an engineering tradeoff that can be selected based on target specifications and layout constraints of a given integrated circuitAttorney Docket No. EMTAR8003WO PATENTimplementation. On one hand, implementing a combined-input feed can reduce the number of coupled-line couplers and associated feed structures used in the second coupled-line differential coupler stage 730, which can reduce routing density and reduce routing discontinuities (e.g., bends, jogs, crossovers, and transitions) in the inter-stage feed region. Reducing routing discontinuities can reduce parasitic perturbations that can otherwise affect amplitude balance and phase balance in the differential paths. On the other hand, because the combined-input embodiment utilizes signal combining prior to the second coupled-line differential coupler stage 730, the combining network can introduce additional insertion loss and can increase matching sensitivity in particular implementations. Accordingly, for a given application, a combined-input feed can be preferred where area efficiency and routing simplicity are prioritized, while a separate-feed architecture (e.g., as described later with respect to FIGS. 8A-8B) can be preferred to reduce pre-stage combining loss or to provide additional degrees of freedom in tuning, depending on requirements such as noise tolerance, loss budget, bandwidth targets, and area constraints.

[0087] FIG. 7B illustrates a corresponding functional block diagram 705 and interconnection scheme for the example three-stage l / Q generator 700 of FIG. 7A. As shown, a first-stage l / Q generation core 710 (e.g., a TF-based l / Q generation core tuned to a first center frequency f 1 ) provides differential in-phase and quadrature signals to a first coupled-line differential coupler stage 720 (e.g., tuned to a second center frequency f2). The outputs of the first coupled-line differential coupler stage 720 can be routed through interconnection paths that implement the combining network to form combined differential in-phase and combined differential quadrature signals, which are then provided as differential inputs to a second coupled-line differential coupler stage 730 (e.g., tuned to a third center frequency f3). In various embodiments, the interconnection paths shown in FIG. 7B (e.g., interconnection paths associated with 0°, 180°, 90°, and 270° components) can be arranged to preserve differential pairing and to support phase matching between corresponding inter-stage paths. In operation, selecting different center frequencies for different stages and arranging the stages such that at least some frequency responses overlap can support a wider operational bandwidth than a single stageAttorney Docket No. EMTAR8003WO PATENTalone. The particular choice of combined-input versus separate-feed inter-stage routing can be selected based on the implementation tradeoffs described above.

[0088] FIG. 8A illustrates a plan view of another example physical layout of a three-stage l / Q generator 800 formed as a conductive layout on a substrate. The three-stage l / Q generator 800 can be generally similar to the three-stage l / Q generator 700 of FIG. 7A, and includes an l / Q generation core 810, a first coupled-line differential coupler stage 820 disposed around the l / Q generation core 810, and a second coupled-line differential coupler stage 830 disposed around the first coupled-line differential coupler stage 820 within a footprint region that includes a core footprint region. In the illustrated implementation, the l / Q generation core 810 is implemented as a TF-based differential coupler using a plurality of concentrically arranged conductive loop segments. The first coupled-line differential coupler stage 820 and the second coupled-line differential coupler stage 830 can each be implemented as respective outer-ring conductive structures relative to the TF-based conductive loop segments of the l / Q generation core 810, such that successive coupled-line stages are integrated in close physical proximity to the l / Q generation core 810.

[0089] In the example of FIG. 8A, the first coupled-line differential coupler stage 820 includes a first-stage in-phase coupled-line coupler and a first-stage quadrature coupled-line coupler arranged around the l / Q generation core 810.Conductive interconnect segments are implemented to route differential in-phase outputs produced by the l / Q generation core 810 to the first-stage in-phase coupled-line coupler, and to route differential quadrature outputs produced by the l / Q generation core 810 to the first-stage quadrature coupled-line coupler. As described above with respect to multi-stage coupled-line implementations, the first coupled-line differential coupler stage 820 can provide (i) a differential in-phase output and (ii) a differential quadrature output, and in some implementations can further provide additional differential components (e.g., a differential quadrature component on the in-phase side and a differential in-phase component on the quadrature side). FIG.8A also illustrates isolation nodes (labeled Isolation) associated with one or more coupled-line structures, which can be used as isolated ports and, in particular implementations, can be coupled to suitable terminations to improve isolation.Moreover, in some embodiments, the first coupled-line differential coupler stage 820Attorney Docket No. EMTAR8003WO PATENTand / or the second coupled-line differential coupler stage 830 can further include one or more grounded isolation conductors (e.g., grounded guard traces, such as those introduced in FIGS. 6A-6B) disposed between differential conductive traces to improve isolation, with placement and geometry selected based on layout density and coupling targets.

[0090] In contrast to FIGS. 7A and 7B, FIGS. 8A and 8B illustrate an implementation in which outputs from the first coupled-line differential coupler stage 820 are fed separately into the second coupled-line differential coupler stage 830 rather than being combined prior to the second coupled-line stage. More specifically, in one or more embodiments, the second coupled-line differential coupler stage 830 includes multiple coupled-line couplers (e.g., four coupled-line couplers) configured to receive, as respective differential inputs, separate differential outputs produced by the first coupled-line differential coupler stage 820. For example, a first set of one or more second-stage coupled-line couplers can be configured to receive a differential signal corresponding to a 07180° component produced by the first coupled-line differential coupler stage 820, and a second set of one or more second-stage coupled-line couplers can be configured to receive a differential signal corresponding to a 90 270° component produced by the first coupled-line differential coupler stage 820. The second coupled-line differential coupler stage 830 can then generate a second-stage set of differential outputs that include an in-phase component (e.g., corresponding to 0° and 180° components) and a quadrature component (e.g., corresponding to 90° and 270° components). In a number of embodiments, the second coupled-line differential coupler stage 830 can be implemented as a second outer-ring conductive structure surrounding the conductive structures of the first coupled-line differential coupler stage 820, thereby extending the architecture to additional stages through layout-driven addition of outer coupled-line structures around a common TF-based l / Q generation core 810.

[0091] It is recognized in the present disclosure that implementing the separate-feed inter-stage routing of FIGS. 8A and 8B can represent an engineering tradeoff that can be selected based on target specifications and layout constraints of a given integrated circuit implementation. On one hand, because a separate-feed implementation can avoid a pre-stage combining network, the separate-feed implementation can reduce combining-related insertion loss and can reduceAttorney Docket No. EMTAR8003WO PATENTsensitivity to combining-network impedance matching in particular implementations. Further, by maintaining separate signal paths into the second coupled-line differential coupler stage 830 (e.g., via multiple second-stage coupled-line couplers), the separate-feed implementation can provide additional degrees of freedom for inter-stage tuning (e.g., through selection of trace geometry, spacing, and coupling for each feed path) in a manner that can be useful for meeting phase-balance and amplitude-balance targets over a desired bandwidth. On the other hand, because the separate-feed implementation uses additional coupled-line couplers and associated feed structures in the second coupled-line differential coupler stage 830, the separate-feed implementation can increase routing density and can introduce additional routing discontinuities (e.g., bends, jogs, crossovers, and transitions) in the inter-stage feed region, which can increase layout complexity and can consume additional real estate in some implementations. Accordingly, for a given application, the separate-feed embodiment can be preferred where loss budget, noise tolerance, and tuning flexibility are prioritized, while a combined-input embodiment (e.g., as described above with respect to FIGS. 7A and 7B) can be preferred where area efficiency and routing simplicity are prioritized, depending on requirements such as operational bandwidth, insertion loss, matching robustness, and area constraints.

[0092] FIG. 8B illustrates a corresponding functional block diagram 805 and interconnection scheme for the example three-stage l / Q generator 800 of FIG. 8A. As shown, a first-stage l / Q generation core 810 (e.g., a TF-based l / Q generation core tuned to a first center frequency f 1 ) provides differential in-phase and quadrature signals to a first coupled-line differential coupler stage 820 (e.g., tuned to a second center frequency f2). The outputs of the first coupled-line differential coupler stage 820 are routed through interconnection paths and provided as separate differential inputs to the second coupled-line differential coupler stage 830 (e.g., tuned to a third center frequency f3), for example without combining the outputs into a single combined differential in-phase signal and a single combined differential quadrature signal prior to the second coupled-line stage. In various embodiments, the interconnection paths shown in FIG. 8B (e.g., interconnection paths associated with 0°, 180°, 90°, and 270° components) can be arranged to preserve differential pairing and to support phase matching between corresponding inter-stage paths. In operation, selecting different center frequencies for differentAttorney Docket No. EMTAR8003WO PATENTstages and arranging the stages such that at least some frequency responses overlap can support a wider operational bandwidth than a single stage alone. The particular choice of separate-feed versus combined-input inter-stage routing can be selected based on the implementation tradeoffs described above.

[0093] FIG. 9 illustrates a plan view of an example physical layout of an l / Q generator 900 formed as a conductive layout on a substrate, and further illustrates example overall footprint dimensions for the l / Q generator 900. In the illustrated example, the l / Q generator 900 implements the presently disclosed techniques as a two-stage architecture that includes a TF-based l / Q generation core disposed within a footprint region and a coupled-line differential coupler stage disposed around the TF-based l / Q generation core within a footprint region that includes a core footprint region.

[0094] As shown in FIG. 9, the example overall footprint of the l / Q generator 900 is approximately 620 micrometers (pm) by 620 pm, corresponding to an area of approximately 0.384 square millimeters (mm2). This footprint can represent an overall plan-view region of the conductive layout (e.g., an approximate bounding box that encompasses the TF-based conductive loop segments, the surrounding coupled-line conductive structures, and associated routing to and from the generator).

[0095] FIG. 9 also provides an illustrative comparison to a reference implementation in which multiple TF-based cores are replicated to realize a multistage configuration. For example, a TF-based core of the type illustrated in FIG. 9 can have an individual footprint on the order of about 400 pm by 400 pm (approximately 0.16 mm2). In a conventional approach that implements a two-stage configuration by cascading and routing among three TF-based cores, the corresponding layout area can be on the order of about 3 x (400 pm x 400 pm), or approximately 0.48 mm2, exclusive of any additional routing keep-out regions or spacing constraints. As such, relative to that illustrative reference, the example two-stage layout of FIG. 9 (approximately 0.384 mm2) can reduce the area budget by about 20 percent.

[0096] Overall, the embodiments of the present disclosure can provide a compact and scalable differential l / Q generator architecture in which a TF-based l / Q generation core is reused while one or more coupled-line differential coupler stagesAttorney Docket No. EMTAR8003WO PATENTare implemented as surrounding outer-ring conductive structures within a footprint region that includes the core footprint region. By extending bandwidth or multi-stage behavior through layout-driven addition of outer coupled-line stages, rather than through replication of standalone TF-based coupler blocks and long phase-matching interconnects, the disclosed approaches can reduce overall layout area for a given set of target specifications while maintaining suitable amplitude balance, phase balance, insertion loss, and operational bandwidth.

[0097] The foregoing description of various embodiments of the claimed subject matter has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed. Many modifications and variations will be apparent to one skilled in the art. Embodiments were chosen and described in order to best describe the principles of the invention and its practical applications, thereby enabling those skilled in the relevant art to understand the claimed subject matter, the various embodiments, and the various modifications that are suited to the particular uses contemplated.

[0098] Although the Detailed Description describes certain embodiments and the best mode contemplated, the technology can be practiced in many ways no matter how detailed the Detailed Description appears. Embodiments may vary considerably in their implementation details, while still being encompassed by the specification. Particular terminology used when describing certain features or aspects of various embodiments should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific embodiments disclosed in the specification, unless those terms are explicitly defined herein. Accordingly, the actual scope of the technology encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the embodiments.

[0099] The language used in the specification has been principally selected for readability and instructional purposes. It may not have been selected to delineate or circumscribe the subject matter. It is therefore intended that the scope of the technology be limited not by this Detailed Description, but rather by any claims thatAttorney Docket No. EMTAR8003WO PATENTissue on an application based hereon. Accordingly, the disclosure of various embodiments is intended to be illustrative, but not limiting, of the scope of the technology as set forth in the following claims. Further, it should be noted that the various circuits disclosed herein may be described using computer-aided design tools and expressed (or represented), as data and / or instructions embodied in various computer-readable media, in terms of their behavioral, register transfer, logic component, transistor, layout geometries, and / or other characteristics. Formats of files and other objects in which such circuit expressions may be implemented include, but are not limited to, formats supporting behavioral languages such as C, Verilog, and VHDL; formats supporting register- 1 eve I description languages like RTL; formats supporting geometry description languages such as GDSII, GDSIII, GDSIV, CIF, MEBES; and any other suitable format or language. Computer-readable media in which such formatted data and / or instructions may be embodied include, but are not limited to, non-volatile storage media in various forms (e.g., optical, magnetic, or semiconductor storage media).

Claims

Attorney Docket No. EMTAR8003WO PATENT CLAIMSWhat is claimed is:1 . An in-phase / quadrature (l / Q) generator comprising:a substrate;a conductive layout formed on the substrate and having:(1) an l / Q generation core occupying a core footprint region, the l / Q generation core having a transformer (TF)-based differential coupler that includes:a first differential input port including a first input node (ln / 0) and a second input node (ln / 180);a first differential in-phase output port including a first in-phase output node (Out / O) and a second in-phase output node (Qut / 180); anda first differential quadrature output port including a first quadrature output node (Qut / 90) and a second quadrature output node (Qut / 270); and(2) a first coupled-line differential coupler stage disposed around the l / Q generation core within a footprint region that includes the core footprint region, the first coupled-line differential coupler stage including:an in-phase coupled-line coupler configured to receive a first differential signal from the first differential in-phase output port of the l / Q generation core and to provide a differential in-phase and quadrature output; anda quadrature coupled-line coupler configured to receive a second differential signal, that is in quadrature with the first differential signal, from the first differential quadrature output port of the l / Q generation core and to provide a differential in-phase and quadrature output,wherein the conductive layout includes a plurality of concentrically arranged conductive loop segments that implement the TF-based differential coupler and are surrounded, within a footprint region that includes the core footprint region, by conductive loop segments that implement the first coupled-line differential coupler stage.

2. The l / Q generator of claim 1 , wherein the in-phase coupled-line coupler and the quadrature coupled-line coupler are primarily implemented in a same metal layer.Attorney Docket No. EMTAR8003WO PATENT3. The l / Q generator of claim 1 , wherein the in-phase coupled-line coupler and the quadrature coupled-line coupler are primarily implemented in different metal layers.

4. The l / Q generator of claim 3, wherein, in a plan view of the substrate, a portion of the in-phase coupled-line coupler vertically overlaps a portion of the quadrature coupled-line coupler.

5. The l / Q generator of claim 1 , wherein the first coupled-line differential coupler stage further includes a grounded isolation conductor disposed between one or more pairs of conductive traces that carry differential signals in the first coupled-line differential coupler stage.

6. The l / Q generator of claim 1 , wherein the first coupled-line differential coupler stage further includes a grounded isolation conductor disposed between differential conductive traces of the in-phase coupled-line coupler and / or between differential conductive traces of the quadrature coupled-line coupler.

7. The l / Q generator of claim 6, wherein the grounded isolation conductor extends along a length of the in-phase coupled-line coupler and / or the quadrature coupled-line coupler.

8. The l / Q generator of claim 1 ,wherein the in-phase coupled-line coupler and the quadrature coupled-line coupler are primarily implemented in a same metal layer, andwherein the first coupled-line differential coupler stage further includes a grounded isolation conductor disposed between differential conductive traces of the in-phase coupled-line coupler and between differential conductive traces of the quadrature coupled-line coupler.

9. The l / Q generator of claim 1 ,wherein the in-phase coupled-line coupler and the quadrature coupled-line coupler are primarily implemented in different metal layers, andAttorney Docket No. EMTAR8003WO PATENTwherein the first coupled-line differential coupler stage further includes a grounded isolation conductor disposed between differential conductive traces of the in-phase coupled-line coupler and between differential conductive traces of the quadrature coupled-line coupler.

10. The l / Q generator of claim 1 , further comprising:(3) a second coupled-line differential coupler stage disposed around, and conductively coupled to, the first coupled-line differential coupler stage, wherein the second coupled-line differential coupler stage is disposed around the first coupled-line differential coupler stage within a footprint region that includes the core footprint region.

11. The l / Q generator of claim 10, wherein the second coupled-line differential coupler stage is implemented as a second outer ring conductive structure that surrounds the conductive loop segments implementing the first coupled-line differential coupler stage.

12. The l / Q generator of claim 10, wherein the l / Q generation core is reused by the second coupled-line differential coupler stage as a common TF-based differential coupler.

13. The l / Q generator of claim 12, wherein the first and / or the second coupled-line differential coupler stage further includes a grounded isolation conductor disposed between one or more pairs of conductive traces that carry differential signals.

14. The l / Q generator of claim 10,wherein the second coupled-line differential coupler stage includes two coupled-line couplers that are configured to receive differential signals from outputs of the first coupled-line differential coupler stage.

15. The l / Q generator of claim 14,Attorney Docket No. EMTAR8003WO PATENTwherein the in-phase coupled-line coupler of the first coupled-line differential coupler stage further provides a first differential quadrature component in addition to the differential in-phase output, andwherein the quadrature coupled-line coupler of the first coupled-line differential coupler stage further provides a second differential in-phase component in addition to the differential quadrature output.

16. The l / Q generator of claim 15, further comprising a combining network configured to:combine the differential in-phase output provided by the in-phase coupled-line coupler with the second differential in-phase component provided by the quadrature coupled-line coupler to form a combined differential in-phase signal; and combine the differential quadrature output provided by the quadrature coupled-line coupler with the first differential quadrature component provided by the in-phase coupled-line coupler to form a combined differential quadrature signal.

17. The l / Q generator of claim 15, wherein the second coupled-line differential coupler stage is configured to:receive the combined differential in-phase signal and the combined differential quadrature signal as respective differential inputs, andgenerate, based on the respective differential inputs, a second-stage set of in-phase and quadrature differential outputs.

18. The l / Q generator of claim 10, wherein the second coupled-line differential coupler stage includes four coupled-line couplers that are configured to receive outputs produced by the first coupled-line differential coupler stage.

19. The l / Q generator of claim 18, wherein the four coupled-line couplers include:(a) a first second-stage coupled-line coupler configured to receive a first differential signal corresponding to a 07180° component produced by the first coupled-line differential coupler stage;Attorney Docket No. EMTAR8003WO PATENT(b) a second second-stage coupled-line coupler configured to receive a second differential signal corresponding to a 907270° component produced by the first coupled-line differential coupler stage;(c) a third second-stage coupled-line coupler configured to receive a third differential signal corresponding to a 0 180° component produced by the first coupled-line differential coupler stage; and(d) a fourth second-stage coupled-line coupler configured to receive a fourth differential signal corresponding to a 907270° component produced by the first coupled-line differential coupler stage.

20. The l / Q generator of claim 10,wherein the TF-based differential coupler of the l / Q generation core is tuned to a first center frequency,wherein the first coupled-line differential coupler stage is tuned to a second center frequency,wherein the second coupled-line differential coupler stage is tuned to a third center frequency, andwherein the second center frequency and the third center frequency are different from the first center frequency.

21. The l / Q generator of claim 20, wherein the second center frequency and the third center frequency are selected such that frequency responses of at least some of the stages overlap to provide a wider operational bandwidth than a single stage alone.

22. The l / Q generator of claim 1 ,wherein the l / Q generation core is tuned to a first center frequency, and wherein the in-phase coupled-line coupler and the quadrature coupled-line coupler are tuned to a second center frequency that is different from the first center frequency.Attorney Docket No. EMTAR8003WO PATENT23. The l / Q generator of claim 1 , wherein each of the in-phase coupled-line coupler and the quadrature coupled-line coupler includes a respective pair of isolation ports.

24. The l / Q generator of claim 1 , wherein the in-phase coupled-line coupler and the quadrature coupled-line coupler are arranged symmetrically about a centerline of the core footprint region.

25. The l / Q generator of claim 1 ,wherein the plurality of concentrically arranged conductive loop segments that implement the TF-based differential coupler include an innermost conductive loop and a second conductive loop surrounding the innermost conductive loop, wherein the innermost conductive loop is physically connected to the second conductive loop via two bridges, each at a connection location, along a perimeter of the innermost conductive loop, andwherein the two bridges’ respective connection locations are symmetrical about a central axis of the conductive layout.

26. The l / Q generator of claim 25, wherein the TF-based differential coupler has an improved shape symmetry and / or length symmetry as compared to without two bridges.

27. The l / Q generator of claim 1 , wherein the TF-based differential coupler includes a pair of conductive loop segments that are mirror symmetric about the centerline of the core footprint region.

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