Compact broadband transformer-based quadrature hybrid coupler

Abstract

Compared to the conventional QHC (30), the compact broadband transformer-based quadrature hybrid coupler (QHC) (34) exhibits improved gain and phase imbalance over a broadband frequency range. The QHC (34) comprises a combination of the conventional transformer-based QHC (30) and a constant-impedance bridge T-type all-pass delay element (32). The QHC (34) operates as a 90° phase-shift splitter and combiner. Applications of the QHC (34) include balanced amplifiers and load-modulated balanced PAs (LMBA). The constant-impedance network provides a discrete equivalent of a broadband dispersion-free transmission line, increasing the bandwidth of the QHC (34). It introduces a constant phase delay for all frequencies. However, more than just a combination of these two circuits, the QHC (34) of this invention incorporates several passive components (inductors / transformers) to reduce the number of components, and some capacitors are conveniently placed in the center of the transformer, forming a compact broadband QHC (34).

Description

Technical Field

[0001] This disclosure generally relates to wireless communication, and more particularly to an orthogonal hybrid coupler that has excellent performance over a wide bandwidth and a compact physical layout. Background Technology

[0002] Wireless communication networks are ubiquitous in many parts of the world. These networks are constantly growing in capacity and complexity. To accommodate more users, different types of devices, and diverse use cases, the technical standards governing the operation of wireless communication networks continue to evolve. The fourth-generation (4G) network standard has been deployed, the fifth generation (5G) is under development and early deployment, and the sixth generation (6G) is in the design phase. With each generation, technological advancements have improved the capacity and spectral efficiency of wireless communication systems. For example, 5G added new frequency bands and applied beamforming. This trend is expected to continue in 6G by utilizing additional frequency bands and applying more advanced beamforming.

[0003] 5G adds a second frequency range, FR2. This provides a large amount of new available spectrum in the 24.25 to 52.6 GHz range. At these high frequencies, wavelengths are small. This is advantageous because antenna elements are also small, allowing for antenna arrays with hundreds or even thousands of antenna elements. However, carriers at these high frequencies suffer higher path loss compared to conventional radio operating frequencies, and therefore have limited range. Beamforming is a technique employed in 5G and 6G to improve both coverage and capacity.

[0004] Beamforming refers to the use of antennas with increased and controllable directivity, resulting in a narrow RF transmission (or receive sensitivity) that is "aimed" in a specific direction. This is enabled by transmitting or receiving signals with controlled relative phase and gain in antenna elements (or subarrays of antenna elements). For example, the relative phase of the transmitted signal sent to each antenna element is controlled to create constructive or destructive interference, thereby amplifying the signal in some directions and attenuating it in others, and thus controlling the direction in which the beam is transmitted. Similar phase manipulation of signals from antenna elements (or subarrays) in the receiving antenna can also result in beamforming, increasing the sensitivity of the antenna array in the received signal. Furthermore, multiple orthogonal beams can be formed and aligned in different directions to simultaneously address multiple wireless devices, also known as user equipment (UEs).

[0005] To form robust beams, antenna elements are typically placed close together. For example, a distance of λ / 2 (where λ is the RF wavelength) is often used to form an undulating arbitrary beam. However, this tight antenna spacing leads to high electromagnetic coupling between the antennas, and further, to signal leakage between them. Beam pointing, combined with antenna coupling, causes the impedance seen by each power amplifier (PA) driving the antenna element (or subarray) to deviate from its design impedance.

[0006] A power amplifier (PA) is designed assuming a nominal load impedance to achieve optimal output power, linearity, and efficiency. The PA amplifies and delivers power to the antenna elements / subarrays, which convert it into electromagnetic signals. However, if the load impedance seen by the PA deviates from its designed (optimal) value, impedance mismatch occurs, degrading PA performance.

[0007] To direct the beam in the desired direction, a phase shift is required between the signals sent to the different antenna elements (or subarrays). Besides the phase shift, the same signal exists on all antenna elements, and the electromagnetic energy of the signal leaks between them. The PA (Power Amplifier) ​​considers this a mismatch with optimal (matched) impedance, which does not exist when no phase shift is introduced to control the beam. The design impedance seen by the PA is called the impedance in the line-of-sight direction (i.e., the direction in which the RF signal is radiated perpendicular to the antenna element plane). When there is coupling between antenna elements (due to spacing), and the same signal is sent on all antennas but with different phases, this situation is perceived by the PA as a load impedance variation and mismatch, even though it stems from antenna leakage and delays introduced by the phase shifter (i.e., the mismatch typically becomes more pronounced with increasing beam angle because of the increased relative phase shift between antennas). Because impedance mismatch causes the RF signal to be partially reflected back to the PA from the antenna elements (or subarrays), a standing wave (SWR) is generated along the transmission line connecting the two. This is quantified in the art as the antenna impedance voltage standing wave ratio (VSWR), which is calculated based on the reflection coefficient or return loss (also known as the S11 parameter). Assuming the antenna and PA are impedance matched for the signal transmitted in the line-of-sight direction, the active impedance load, or VSWR, typically increases with increasing beam angle because of the increased relative phase shift between antenna elements (or subarrays).

[0008] Therefore, when the PA is coupled to the antenna, the PA and the antenna elements interact through antenna coupling. Consequently, due to beamforming, the PA effectively experiences time-varying impedance mismatch, denoted by VSWR. VSWR affects the PA's output power, efficiency, and linearity, and thus, the phased array beam and its orientation.

[0009] At low frequencies, isolators can be inserted between the PA and its antenna elements / subarrays to ensure that VSWR is not propagated to the PA. In high-frequency advanced antenna systems (AAS), there is no space to install isolators at each PA output.

[0010] Therefore, reducing the PA's sensitivity to varying load impedance will improve the performance of the RF system. Various methods for reducing PA load sensitivity are known in the art.

[0011] As shown in Figure 1, a known method to reduce the sensitivity of a power amplifier (PA) to impedance mismatch is to use a balanced PA circuit. A balanced PA consists of two amplifiers, each amplifying the same RF signal but with a 90° phase offset (quadrature). An input splitter, such as a quadrature hybrid coupler (QHC), splits the RF signal to be amplified into two RF signals with a quadrature phase relationship. The output QHC acts as a signal combiner, combining the amplified quadrature RF signals into a single output RF signal. Figure 1 shows the impedance matching circuit at the PA output. As is known in the art, input impedance matching can also be implemented, or alternatively, a balanced PA can be implemented without input or output matching. Balanced PAs are highly insensitive to changes in load impedance and are therefore a good choice for RF PAs used in beamforming systems.

[0012] However, traditional QHCs have many limitations. They are inherently narrowband and offer good amplitude balance and phase coherence, but only within a limited frequency range. QHCs can be implemented using transmission lines or lumped reactance elements, both of which require significant amounts of die space on integrated circuits. This makes layout challenging, especially for driven phased array antennas with tight spacing between antenna elements.

[0013] The background section of this document is provided to place aspects of this disclosure within a technical and operational context to assist those skilled in the art in understanding their scope and applicability. The methods described in the background section may be employed, but are not necessarily methods previously conceived or employed. Unless expressly stated otherwise, no statement herein should be construed as prior art solely by incorporating it into the background section. Summary of the Invention

[0014] The following is a simplified summary of the invention disclosed to provide a basic understanding to those skilled in the art. This summary is not a broad overview of the disclosure and is not intended to identify key / essential elements of any aspect of the disclosure or to define its scope. The sole purpose of this summary is to present some of the concepts disclosed herein in a simplified form as a prelude to a more detailed description that follows.

[0015] The compact broadband transformer-based transmission line quadrature hybrid coupler (QHC) addresses the limitations of traditional QHCs. The QHC consists of a combination of a traditional transformer-based QHC and a constant-resistance (constant-R) bridge T-type all-pass delay element. The QHC traditionally operates—as a 90° phase-shift splitter and combiner. This isolated port provides the possibility of use as a load-modulated balanced PA (LMBA). The constant-resistance network provides a discrete equivalent of a broadband, dispersion-free transmission line (ideally down to DC) and introduces a nearly constant phase delay across all frequencies, while simultaneously increasing the QHC bandwidth.

[0016] Constant-impedance networks provide a discrete equivalent of a broadband, dispersion-free transmission line (ideally down to DC) and introduce a nearly constant phase delay for all frequencies, while increasing the QHC bandwidth. However, the circuit of this invention is not simply a combination of these two circuits, but rather incorporates several passive components (inductors / transformers) to reduce the number of components, and some capacitors are conveniently arranged in the center of the transformer, thus forming a compact, broadband QHC.

[0017] One aspect relates to a compact broadband QHC. The QHC includes a transformer comprising a primary winding connected between a first port and a second port, the primary winding including a first inductor portion and a second inductor portion connected at a first node. The transformer also includes a secondary winding connected between a third port and a fourth port, the secondary winding including a third inductor portion and a fourth inductor portion connected at a second node. All first, second, third, and fourth inductor portions are configured to be inductively coupled. The QHC also includes a first capacitor connected between the first and third ports; a second capacitor connected between the second and fourth ports; a third capacitor connected between the first and second nodes; a first parallel capacitor connected between the first node and a ground node; and a second parallel capacitor connected between the second node and a ground node.

[0018] On the other hand, a balanced RF power amplifier (PA) is involved. The balanced RF PA includes: an input QHC as described above, configured to receive an RF signal at a first port and output quadrature RF signals at a second and a third port; two RF PAs, each configured to amplify one of the quadrature RF signals output from the input QHC; and an output QHC configured to receive the amplified quadrature RF signals output from the RF PAs at the second and a third port and output a single combined amplified RF signal at the first port.

[0019] Another aspect relates to a wireless device operating in a wireless communication network. The wireless device includes processing circuitry and communication circuitry operatively connected to the processing circuitry. The communication circuitry includes one or more compact broadband transformer-based QHCs. Each QHC includes a transformer comprising a primary winding connected between a first port and a second port, the primary winding including a first inductor portion and a second inductor portion connected at a first node. The transformer also includes a secondary winding connected between a third port and a fourth port, the secondary winding including a third inductor portion and a fourth inductor portion connected at a second node. All first, second, third, and fourth inductor portions are configured to be inductively coupled. Each QHC also includes a first capacitor connected between the first and third ports; a second capacitor connected between the second and fourth ports; a third capacitor connected between the first and second nodes; a first parallel capacitor connected between the first node and a ground node; and a second parallel capacitor connected between the second node and a ground node.

[0020] Another aspect relates to a base station operating in a wireless communication network. The base station includes processing circuitry and communication circuitry operatively connected to the processing circuitry. The communication circuitry includes one or more compact broadband QHCs. Each QHC includes a transformer comprising a primary winding connected between a first port and a second port, the primary winding including a first inductor portion and a second inductor portion connected at a first node. The transformer also includes a secondary winding connected between a third port and a fourth port, the secondary winding including a third inductor portion and a fourth inductor portion connected at a second node. All first, second, third, and fourth inductor portions are configured to be inductively coupled. Each QHC also includes a first capacitor connected between the first and third ports; a second capacitor connected between the second and fourth ports; a third capacitor connected between the first and second nodes; a first parallel capacitor connected between the first node and a ground node; and a second parallel capacitor connected between the second node and the ground node. Attached Figure Description

[0021] This disclosure will now be described more fully below with reference to the accompanying drawings, in which various aspects of this disclosure are illustrated. However, this disclosure should not be construed as limited to the aspects set forth herein. Rather, these aspects are provided so that this disclosure will be thorough and complete and will fully convey the scope of this disclosure to those skilled in the art. The same numerals refer to the same elements throughout.

[0022] Figure 1 illustrates a known balanced power amplifier (PA) circuit that uses an orthogonal hybrid coupler (QHC) as both a splitter and combiner.

[0023] Figure 2 illustrates a known implementation of QHC using transmission lines or microstrips.

[0024] Figure 3A depicts a known implementation of QHC using coupled transmission lines.

[0025] Figure 3B is the equivalent circuit model of the coupled transmission line QHC in Figure 3A.

[0026] Figure 4 depicts the known Lange QHC.

[0027] Figure 5A depicts a known inductor-based QHC.

[0028] Figure 5B depicts a known transformer-based QHC.

[0029] Figure 6 illustrates the general case of a known transformer-based QHC.

[0030] Figure 7 shows a known constant-impedance bridge T-type all-pass delay circuit.

[0031] Figure 8 A compact broadband transformer-based QHC is described, which is formed by replacing each winding in the transformer-based QHC of Figure 6 with the constant-impedance bridge T-type all-pass delay circuit of Figure 7.

[0032] Figure 9 Describing the target Figure 8 Compact broadband QHC multi-layer layout options based on transformers.

[0033] Figure 10 The figure shows the simulated phase difference between the coupled port and the through port for a conventional transformer-based QHC in the FR2 operating band of 37-43.5 GHz.

[0034] Figure 11 It is for the FR2 operating frequency band of 37-43.5GHz. Figure 8 A plot of the simulated phase difference between the coupled port and the through port of a compact broadband transformer-based QHC.

[0035] Figure 12 The graph shows the simulated gain imbalance between the coupled port and the through port for a conventional transformer-based QHC in the FR2 operating band of 37-43.5 GHz, as shown in Figure 6.

[0036] Figure 13 It is for the FR2 operating frequency band of 37-43.5GHz. Figure 8 A graph of the gain imbalance of a compact broadband transformer-based QHC between coupled and through ports.

[0037] Figure 14The graph shows the input port voltage reflection coefficient (S11) of the conventional transformer-based QHC simulation in the FR2 operating band of 37-43.5 GHz.

[0038] Figure 15 It is targeting the FR2 operating band of 37-43.5GHz. Figure 8 A graph showing the input port voltage reflection coefficient (S11) of a compact broadband transformer-based QHC simulation.

[0039] Figure 16 This is a block diagram of a wireless device operating in a wireless communication network.

[0040] Figure 17 This is a block diagram of a base station operating in a wireless communication network. Detailed Implementation

[0041] For purposes of brevity and explanation, this disclosure is described primarily by reference to exemplary aspects thereof. Numerous specific details are set forth in the following description in order to provide a thorough understanding of this disclosure. However, it will be readily apparent to those skilled in the art that this disclosure may be practiced without being limited to these specific details. Well-known methods and structures are not described in detail in this specification so as not to unnecessarily obscure this disclosure.

[0042] As mentioned above, compact, wideband, low component count, and highly integrable QHCs will benefit modern wireless communication systems, especially those that implement beamforming.

[0043] A QHC is a special case of a general category of directional couplers, for which coupling is 3dB. An ideal QHC is a symmetrical, lossless, passive four-port network. The ports of a QHC are typically labeled SIGNAL, COUPLED, THROUGH, and ISOLATED. When configured as a splitter, the RF signal input to the SIGNAL port appears at the COUPLED port with a -3dB attenuation and no phase shift. The same signal appears at the THROUGH port with the same -3dB attenuation and a -90° phase difference. Because it is symmetrical, a QHC can combine two orthogonal input signals (i.e., with a 90° phase shift) at the THROUGH and COUPLED ports into a single output signal at the SIGNAL port. When configured as a splitter or combiner, the ISOLATED port is typically terminated to ground via a characteristic impedance (e.g., 50Ω).

[0044] QHC can also be a device that can replace a traditional quadrature coupler and, in some cases, a multiphase filter (PPF), for example, in a vector modulator or phase shifter with a Gilbert unit design employing quadrature inputs, and in a mixer (upconverter or downconverter) with quadrature LO drive for LO suppression and / or image suppression via quadrature IF / RF input / output.

[0045] Figure 2 illustrates one implementation of a QHC using a transmission line or microstrip (referred to as a branch-line coupler). The transmission line has an electrical length of λ / 4, where λ is the wavelength of the fundamental frequency. Since the transmission line is determined by a single frequency, this type of QHC is inherently narrowband. The evolution of modern wireless communication is clearly moving towards greater bandwidth. Furthermore, transmission lines require a significant amount of valuable IC die space, especially for phased array antennas, where the spacing between antenna elements on the PCB / substrate is decreasing and must be compatible with the on-chip TX / RX port spacing.

[0046] Other implementations of QHC include the coupled-line configuration shown in Figure 3A with the equivalent circuit model in Figure 3B, and the Lange configuration QHC shown in Figure 4.

[0047] For on-chip implementation, inductor- or transformer-based coupled QHCs are preferred. Figure 5A illustrates the inductor-based option, and Figure 5B illustrates the transformer-based QHC. As described in the paper "2 GHz Quadrature Hybrid Implementation in CMOS Technology" by Robert C. Frye et al., published on page 287 of the IEEE 2002 Custom Integrated Circuits Conference, the design equations for tuning and coupling capacitors, as well as the inductor dimensions with the necessary coupling factor, are derived from the required characteristic impedance and operating frequency; the entire contents of that paper are incorporated herein by reference. As shown in Figures 5A and 5B, lumped-element QHCs require six capacitors for tuning and correcting signal phase. The layout of these circuits is challenging and requires accurate modeling of the effects of wiring to capture the correct frequency characteristics. Furthermore, Frye's paper concludes that the relative bandwidth of a lumped-element QHC with good amplitude balance (within 0.1 dB) and the desired phase difference (within 2 degrees) is approximately 30% of the resonant frequency. However, that is the performance of an ideal QHC. When implemented on a chip, performance may be expected to deviate significantly, primarily due to the non-negligible series resistance of the inductor windings and substrate losses.

[0048] It is also known to use RC polyphase networks in IC design to generate quadrature signals. However, these typically suffer from high losses, especially if they are widened by adding several poles.

[0049] Figure 6 depicts a transformer-based QHC 30, similar to, but more generally generalized to, the transformer-based QHC depicted in Figure 5B. The primary and secondary windings of the transformer are implemented as inductors L1. Inductors L1 have the same inductance, so transformer 30 neither raises nor lowers its input voltage. The term k is a coupling factor, for example 0.707, which depends on the inductor coupling. The coupling factor k is engineered by controlling the size and length of the inductor L1 traces and their proximity on the die. As described above, the transformer-based QHC 30 exhibits good amplitude balance and maintains a 90° phase shift only over a relatively narrow bandwidth.

[0050] Figure 7 depicts a constant-impedance bridge T-type all-pass delay circuit 32. The inductor bridge T-type circuit (also known as a T-coil) is a form of inductor peaking circuit. It is commonly used to extend the bandwidth of an amplifier (e.g., double it) and can improve the rise time of the output signal. Circuit 32 includes an inductor L1 with a center tap formed by parallel capacitors and a bridging capacitor spanning from the input to the output. A coupling factor k inductively couples the left and right sides of the inductor (which can be implemented as two series inductors). The bridging capacitor ensures that the input impedance of the bridge T-type circuit 32 is constant and resistive—hence the characteristic "constant-impedance bridge T-type".

[0051] According to aspects of this disclosure, by replacing each of the inductor L1 (i.e., transformer winding) and capacitor CG of the transformer-based QHC 30 with a constant-resistance bridge T-type circuit 32, the bandwidth of the transformer-based QHC 30 is improved. The equivalent circuit of Cshunt in Figure 7 is shown in Figure 7. Figure 8 The network is split into C2a, C2b, and C3. This can be viewed as a “hybrid” between two coupled bridge T-networks and a traditional transformer-based cascaded two-stage design. This provides a discrete equivalent of a broadband (ideally down to DC) dispersion-free transmission line. The result is... Figure 8 The compact broadband based on transformer QHC 34 described in the paper.

[0052] Each transformer winding includes a pair of inductors connected in series, which are inductively coupled, as indicated by the left and right curved arrows. The primary and secondary windings are similarly inductively coupled, as indicated by the up and down curved arrows. Furthermore, as indicated by the crossed curved arrows, each inductor is inductively cross-coupled to an inductor at a diagonal location. Each arrow represents a different coupling factor k between any pair of inductors. Therefore, the compact broadband transformer-based QHC 34 divides the two windings of the transformer-based QHC 30 (Figure 5) into four inductors L1, all of which are inductively cross-coupled. Although not required for operation of the compact broadband transformer-based QHC 34, the inductive cross-coupling between all four inductors L1 is a design parameter that can be optimized for broadband amplitude and phase balance.

[0053] The compact broadband transformer-based QHC 34 function is divided into a broadband section, which adds more degrees of freedom in terms of more coupling and cross-coupling coefficients as well as cross-coupling and parallel capacitors to optimize frequency characteristics.

[0054] Figure 9 One method of physical layout for a compact broadband transformer-based QHC 34 is shown. Figure 9 In this configuration, each transformer winding (including two inductors L1) comprises metal traces on adjacent layers of the die, one trace covering the other, and inductively coupled through a dielectric layer between them. That is, for example, Figure 8 V SIG and V THRU The inductor between the ports covers V CPL and V ISO Inductors between ports (or vice versa). Figure 9 This demonstrates the compactness of this layout option in terms of area.

[0055] like Figure 9 As shown, several tuning capacitors C2 and C3 are placed in the center of the transformer, further reducing the bare die area. Furthermore, the coupling capacitance C4 between each pair of terminals of the inductor (the bridging capacitor in bridge T-circuit 32) may be consumed by layout parasitic effects. This leaves only one unit-sized tuning capacitor C1 between the signal and coupling ports, and another unit-sized tuning capacitor C1 between the through and isolation ports. Therefore, in the physical implementation, instead of six capacitors at the QHC 34 terminal (as shown in QHC 30 in Figure 6), the number is reduced to two capacitors C1. The remaining tuning capacitors can be placed in the center of the transformer, where they are "unaffected" by area considerations.

[0056] right Figure 8A compact broadband transformer-based QHC 34 was simulated and compared with a simulation of a conventional transformer-based QHC 30 (Figure 6). The results are electromagnetic simulations based on QHC structures 30 and 34, with capacitors modeled using millimeter waves.

[0057] Figure 10 The phase difference of 5.60 degrees between the coupled port and the through port is shown for the conventional transformer-based QHC30 in Figure 6 in the FR2 operating band of 37-43.5 GHz. Figure 11 It shows that on the same frequency band, for Figure 8 The compact broadband based transformer QHC 34 has a phase difference of 0.68 degrees between the coupled port and the through port.

[0058] Figure 12 The gain imbalance of 1.71 dB between the coupled port and the through port is shown for the conventional transformer-based QHC30 in Figure 6 in the FR2 operating band of 37-43.5 GHz. Figure 13 This shows that, within the same frequency band, for Figure 8 The compact broadband transformer-based QHC 34 has a gain imbalance of 0.61 dB between the coupled port and the through port.

[0059] Figure 14 The input port voltage reflection coefficient, also known as the S11 parameter, for the conventional transformer-based QHC 30 in Figure 6 in the FR2 operating band of 37-43.5 GHz is shown. The input port voltage reflection coefficient is -18.2 dB. Figure 15 It shows that for Figure 8 The compact broadband transformer-based QHC 34 has an input port voltage reflection coefficient, or S11 parameter, of -18.5 dB in the same frequency band.

[0060] Table 1 lists these simulation values, along with some other parameters of interest.

[0061]

[0062] Table 1: Performance Comparison

[0063] At this frequency range, while the S11 parameters are comparable for both the QHC 30 and 34, the compact broadband transformer-based QHC 34 exhibits a gain imbalance of only ~0.6 dB (compared to ~1.7 dB for the conventional QHC 30) and a phase difference of only ~0.7 degrees (compared to 5.6 degrees for the conventional QHC 30). Furthermore, the compact broadband transformer-based QHC 34 achieves this performance while consuming less than half the die area of ​​the conventional QHC 30, thanks to its compact layout options.

[0064] As described herein (and depicted in Figure 1), one application of the compact broadband transformer-based QHC 34 is in balanced power amplifiers (PAs), particularly in beamforming communication systems, where widely varying load impedances detrimentally affect the performance of conventional PAs. However, the QHC 34 is not subject to this strict limitation. For example, the compact broadband transformer-based QHC 34 is also a preferred option for generating I / Q signals for local oscillators, frequency conversion circuits, and the like.

[0065] The compact broadband transformer-based QHC 34 can be used in a variety of ways. For example, the compact broadband transformer-based QHC 34 can be used to form a balanced PA for driving an antenna array that achieves beamforming.

[0066] PCT patent application No. PCT / EP2023 / 051188, filed January 19, 2023, describes a power amplifier device comprising two balanced amplifiers, each having two PAs and one QHC, and additionally at least one delay line applying a phase shift, and optionally, an output combining network to achieve line averaging, which reduces the sensitivity of the PAs to dynamic load impedance variations (e.g., caused by beamforming). This application references G. Berretta, D. Cristaudo, and S. Scaccianoce's "A Balanced CDMA2000 SiGe HBT Load-Insensitive Power Amplifier," IEEE Radio and Wireless Symposium 2006, pp. 523-526, the contents of which are incorporated herein by reference in their entirety. A compact broadband transformer-based QHC 34 can be advantageously used as the QHC in such applications.

[0067] Figure 16A hardware block diagram of a wireless device 40 implemented according to one or more embodiments is shown. Wireless device 40 is any type of device capable of communicating with network nodes and / or access points using radio signals. Therefore, wireless device 40 can refer to a machine-to-machine (M2M) device, a machine-type communication (MTC) device, a narrowband Internet of Things (NB-IoT) device, etc. Wireless device 40 can also be referred to as user equipment (UE), such as a cellular phone or "smartphone"; however, the term UE should be understood to include any wireless device 40. Wireless device 40 can also be referred to as a radio device, radio communication device, wireless device, wireless terminal, or simply a terminal—unless the context otherwise requires, the use of any of these terms is intended to include device-to-device UE or device, machine-type device or device capable of machine-to-machine communication, sensor equipped with a wireless device, wireless-enabled desktop computer, mobile terminal, smartphone, laptop embedded device (LEE), laptop-installed device (LME), USB dongle, wireless customer premises equipment (CPE), etc. In the discussion herein, the terms machine-to-machine (M2M) device, machine-type communication (MTC) device, wireless sensor, and sensor may also be used. It should be understood that these devices, although referred to as UEs, can be configured to send and / or receive data without direct human interaction.

[0068] In some embodiments, the wireless device 40 includes a user interface 42 (display, touchscreen, keyboard or keypad, microphone, speaker, etc.); in other embodiments, such as in many M2M, MTC, or NB-IoT scenarios, the wireless device 40 may include only a minimal user interface 42 or may not include a user interface 42 at all (e.g., ...). Figure 16 (Indicated by the dashed line in the middle frame 42). The wireless device 40 also includes processing circuitry 44; memory 46; and communication circuitry 48 for wireless communication with one or more radio network nodes (such as base stations and / or access points) via an air interface. The communication circuitry 48 is connected to an antenna element array 49, such as an AAS, which performs beamforming via phase control. As shown by the dashed line, the antenna array 49 may protrude outwards from the wireless device 40, or it may be internal. In some embodiments, the wireless device 40 may include a sophisticated user interface 42 and may additionally include features such as a camera, accelerometer, satellite navigation signal receiver circuitry, vibration motors, etc. Figure 16 (Not depicted in the text).

[0069] According to aspects of this disclosure, the communication circuit 48 includes a parallel structure of balanced PAs constructed using a compact broadband transformer-based QHC 34 as an input and / or output combiner, wherein the balanced PAs have an inherent 90° phase shift between the PAs. This makes the balanced PAs less susceptible to the detrimental effects of dynamic impedance mismatch at the antenna, such as that caused by beamforming. In some embodiments, the balanced PAs may be arranged as described in the aforementioned PCT patent application.

[0070] Figure 17 A hardware block diagram of a base station 50 operating in a wireless communication network is depicted. Base station 50 includes processing circuitry 52; memory 54; and communication circuitry 56 for wireless communication with one or more wireless devices 40 via an air interface. Communication circuitry 56 is connected to an antenna element array 58, such as an AAS, which performs beamforming through phase control. As shown by disconnection from antenna array 58, antenna array 58 can be physically separated from base station 50, for example, mounted on a tower, building, etc. Although memory 56 is depicted as being internal to processing circuitry 54, those skilled in the art will understand that memory 56 can also be external. Those skilled in the art will also understand that virtualization technology allows some functions nominally performed by processing circuitry 54 to actually be performed by other hardware, which may be located remotely (e.g., in the so-called "cloud"). Base station 50 is referred to as an eNodeB or eNB in ​​LTE and as a gNB in ​​New Radio (NR). Typically, in other wireless communication networks, base station 50 may be referred to as a radio base station, base transceiver station, access point, etc.

[0071] According to aspects of this disclosure, the communication circuit 56 includes a parallel structure of balanced PAs constructed using a compact broadband transformer-based QHC 34 as an input and / or output combiner, wherein the balanced PAs have an inherent 90° phase shift between the PAs. This makes the balanced PAs less susceptible to the detrimental effects of dynamic impedance mismatch at the antenna, such as that caused by beamforming. In some embodiments, the balanced PAs may be arranged as described in the aforementioned PCT patent application.

[0072] The circuitry or circuitry portion may include circuitry dedicated to performing certain functional processing and / or one or more microprocessors combined with memory. For example, the circuitry portion may include one or more microprocessors or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), application-specific digital logic, etc. The processing circuitry portion may be configured to execute program code stored in memory, which may include one or more types of memory, such as read-only memory (ROM), random access memory, cache memory, flash memory devices, optical storage devices, etc. In several embodiments, the program code stored in memory may include program instructions for executing one or more telecommunications and / or data communication protocols, and instructions for executing one or more techniques described herein. In embodiments employing memory, the memory stores program code that, when executed by one or more processors, performs the techniques described herein.

[0073] Those skilled in the art will also understand that aspects of this document also include corresponding computer programs.

[0074] A computer program includes instructions that, when executed on at least one processor of the device, cause the device to perform any of the corresponding processes described above. In this respect, the computer program may include one or more code modules corresponding to the aforementioned components or units.

[0075] The aspect also includes a carrier containing such a computer program. This carrier may include one of the following: electronic signals, optical signals, radio signals, or computer-readable storage media.

[0076] In this respect, aspects of this document also include a computer program product stored on a non-transitory computer-readable (storage or recording) medium and comprising instructions that, when executed by a processor of a device, cause the device to perform as described above.

[0077] The aspect also includes a computer program product comprising program code portions for performing the steps of any of the embodiments herein when the computer program product is executed by a computing device. The computer program product may be stored on a computer-readable recording medium.

[0078] Compared to existing technologies, the aspects disclosed herein present numerous advantages. The compact broadband transformer-based QHC34 is wider than the conventional transformer-based QHC32 and is therefore less sensitive to component variations and modeling defects. In particular, simulations show that the amplitude and phase imbalance of the compact broadband transformer-based QHC34 is improved compared to conventional lumped element implementations. In terms of layout, the compact broadband transformer-based QHC34 eliminates the need for λ / 4 transmission lines, reducing die area and improving broadband performance by eliminating the need for designing for a single specific frequency. The transformer windings can be formed by placing loops of metal traces side-by-side on the same layer or stacking loops of metal traces vertically on different layers, choosing the more feasible option depending on the available metal stacks. Both variants work equally well at the theoretical level, provided the desired coupling factor can be achieved. The unavoidable inductive coupling between windings on each side of the center tap, as well as inductive cross-coupling, is a key design feature of the compact broadband transformer-based QHC 34—unlike the conventional transformer-based QHC 30, where these effects are not used or must be compensated for to reduce or eliminate their negative impact on performance. Several tuning capacitors can be placed at the center of the transformer, thereby reducing the occupied die area. Compared to conventional implementations, the number of tuning capacitors at the terminals of the compact broadband transformer-based QHC 34 can be reduced to four, further reducing the footprint and wiring complexity. In some aspects of this disclosure, bridging capacitors with parasitic capacitances caused by the transformer winding layout are implemented (…). Figure 8 The number of capacitors (C4 in the original text) can be reduced to as few as two. The reduced die area required to implement a compact broadband transformer-based QHC 34 is particularly beneficial in the millimeter-wave frequency range, where the spacing between antenna elements on the PCB / substrate is decreasing and must be compatible with the on-chip TX / RX ports. The compact broadband transformer-based QHC 34 can be used to cover a wider bandwidth and allows for non-ideals and model limitations / inaccuracies, especially at millimeter-wave frequencies and as we move toward terahertz frequencies. Possible (non-limiting) applications of the compact broadband transformer-based QHC 34 include 0° / 90° I / Q phase generation and load-insensitive balanced PA designs.

[0079] Generally, all terms used herein should be interpreted according to their ordinary meaning in the relevant art, unless a different meaning is explicitly given and / or implied from the context in which they are used. Unless otherwise expressly stated, all references to an element, device, component, element, step, etc., should be interpreted as referring to at least one instance of the element, device, component, element, step, etc. The steps of any method disclosed herein need not be performed in the exact order disclosed, unless a step is explicitly described as occurring after or before another step and / or implies that a step must occur after or before another step. Any feature of any aspect disclosed herein may be applied to any other aspect, as appropriate. Similarly, any advantage of any aspect may be applied to any other aspect, and vice versa. Other objects, features, and advantages of the appended aspects will be apparent from the description.

[0080] The term “unit” may have a conventional meaning in the field of electronic devices, electrical equipment and / or electronic equipment, and may include, for example, electrical and / or electronic circuits, devices, modules, processors, memories, logic solid-state and / or discrete devices, computer programs or instructions for performing corresponding tasks, programs, calculations, output and / or display functions, as those described herein.

[0081] As used herein, the term “configured to” means to be set, organized, adjusted, or arranged to operate in a particular manner; the term is synonymous with “designed to”.

[0082] Some aspects contemplated herein are described more fully with reference to the accompanying drawings. However, other aspects are included within the scope of the subject matter disclosed herein. The disclosed subject matter should not be construed as limited to the aspects described herein; rather, these aspects are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0083] Of course, this disclosure may be implemented in ways other than those specifically set forth herein without departing from its essential characteristics. This aspect should be considered illustrative rather than restrictive in all respects, and all variations falling within the meaning and equivalents of the appended aspect are intended to be included therein.

Claims

1. A compact broadband orthogonal hybrid coupler QHC (34), comprising: Transformer, the transformer comprising: A primary winding (L1) connected between a first port and a second port, the primary winding comprising a first inductor portion (L1a) and a second inductor portion (L1b) connected at a first node (N1), and A secondary winding (L2) is connected between the third and fourth ports, the secondary winding including a third inductor portion (L2a) and a fourth inductor portion (L2b) connected at the second node (N2). Wherein, all of the first inductor portion, the second inductor portion, the third inductor portion and the fourth inductor portion are configured to be inductively coupled; A first capacitor (C1a) is connected between the first port and the third port. A second capacitor (C1b) is connected between the second port and the fourth port. A third capacitor (C3) is connected between the first node (N1) and the second node (N2); The first parallel capacitor (C2a) connected between the first node (N1) and the ground node (G); and A second parallel capacitor (C2b) is connected between the second node (N2) and the ground node (G).

2. The QHC (34) of claim 1, wherein The primary winding and the secondary winding (L1, L2) are implemented as a loop of metal traces on a semiconductor die, wherein at least one of the first capacitor (C1a), the second capacitor (C1b), the third capacitor (C3), the first parallel capacitor (C2a), and the second parallel capacitor (C2b) is arranged inside the loop.

3. The QHC (34) of claim 2, wherein, The loops that implement the metal traces of the primary winding and the secondary winding (L1, L2) are routed adjacently on the same layer.

4. The QHC (34) of claim 2, wherein, The loop that implements the metal trace of one of the primary winding and the secondary winding (L1, L2) is routed above the other of the primary winding and the secondary winding (L1, L2) and separated by a dielectric layer.

5. The QHC (34) according to any one of claims 1-4, further comprising: The primary winding (L1) spanning between the first port and the second port is connected to a first bridge capacitor (C4a).

6. The QHC (34) according to any one of claims 1-4, further comprising: The second bridge capacitor (C4b) is connected across the secondary winding (L2) between the third port and the fourth port.

7. The QHC (34) according to any one of claims 2-4, wherein, The first port and the second port are connected via a parasitic capacitance (C4a) associated with the primary winding (L1).

8. The QHC (34) according to any one of claims 2-4, wherein, The third port and the fourth port are connected via a parasitic capacitance (C4b) associated with the secondary winding (L2).

9. The QHC (34) according to any one of claims 7-8, wherein, The size and spacing of the metal traces are configured to generate predetermined values ​​for the parasitic capacitances (C4a, C4b).

10. The QHC (34) according to any of the preceding claims, wherein, The RF signal input to the first port is output at equal power at the second and third ports, but with a relative phase shift of 90 degrees.

11. The QHC (34) according to claim 10, wherein, The RF signals output at the second port and the third port have a constant phase delay with no change in frequency.

12. The QHC (34) according to any one of claims 1-9, wherein, The quadrature RF signals input to the second port and the third port are output as a combined signal at the first port.

13. A balanced radio frequency (RF) power amplifier (PA), comprising: According to any one of claims 10-11, the input QHC (34) is configured to receive an RF signal at the first port and output orthogonal RF signals at the second port and the third port; Two RF PAs, each configured to amplify one of the orthogonal RF signals output from the input QHC (34); and According to claim 12, the output QHC (34) is configured to receive amplified quadrature RF signals output by the RF PA at the second port and the third port, and to output a single combined amplified RF signal at the first port.

14. The balanced RF PA according to claim 13, further comprising: Two input impedance matching circuits are provided, each of which is sandwiched between the output port of the input QHC (34) and the input of the associated RF PA.

15. The balanced RF PA according to claim 13, further comprising: Two output impedance matching circuits are provided, each of which is sandwiched between the output port of the RF PA and the associated input port of the output QHC (34).

16. The balanced RF PA according to any one of claims 13-15, further comprising: The termination impedance between the fourth port of the input QHC (34) and the output QHC (34) and ground.

17. A wireless device (40) operating in a wireless communication network, characterized in that: Processing circuit (44); and A communication circuit (48), operably connected to the processing circuit (24), and comprising one or more compact broadband transformer-based orthogonal hybrid couplers (QHCs) (34), each of the one or more compact broadband transformer-based QHCs (34) being characterized in that: A transformer, the transformer including a primary winding connected between a first port and a second port and a secondary winding connected between a third port and a fourth port, wherein the primary winding and the secondary winding are configured to be inductively coupled. The first capacitor connected between the first port and the third port; and A second capacitor connected between the second port and the fourth port; Each of the primary and secondary windings includes a bridge T-type circuit, which includes an inductor, a parallel capacitor connected between the center tap of the inductor and the RF signal ground, and a bridge capacitor connected across the inductor.

18. A base station (50) operating in a wireless communication network, characterized in that: Processing circuit (52); and A communication circuit (56), operably connected to a processing circuit (52), and comprising one or more compact broadband transformer-based orthogonal hybrid couplers (QHCs) (34), each of the one or more compact broadband transformer-based QHCs (34) being characterized in that: A transformer, the transformer including a primary winding connected between a first port and a second port and a secondary winding connected between a third port and a fourth port, wherein the primary winding and the secondary winding are configured to be inductively coupled. The first capacitor connected between the first port and the third port; and A second capacitor connected between the second port and the fourth port; Each of the primary and secondary windings includes a bridge T-type circuit, which includes an inductor, a parallel capacitor connected between the center tap of the inductor and the RF signal ground, and a bridge capacitor connected across the inductor.

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