Coupler device in phased array system

Abstract

This invention provides a coupler device for a phase array system. The coupler device includes an adjustable amplifier and a coupler. The adjustable amplifier is configured to convert an input signal into a first intermediate signal and a second intermediate signal. The coupler is coupled to the adjustable amplifier. The coupler includes: a first input port for receiving the first intermediate signal; a second input port for receiving the second intermediate signal; a first output port for outputting a first output signal; and a second output port for outputting a second output signal. A phase difference between a first phase of the first output signal and a second phase of the second output signal is a fixed phase angle.

Description

Technical Field

[0001] The present invention relates to a wireless communication system, and more particularly, to a coupler device in a phased array system. Prior Art

[0002] Phased array technology has become a key system and subsystem in various applications, including 5G, beyond 5G communications, and radar, due to its ability to form beams, which improves the power link budget and tracking accuracy. Precise control of the amplitude and phase of the RF signals for each antenna is necessary for synthesizing the desired beam pattern. Therefore, for a phased array system, the ability to precisely adjust the phase shift and amplitude weighting is essential. The tuning range of the phase shift and amplitude weighting determines the nature of the beam pattern, such as the beam angle range, beam width, and beam type (e.g., sum or difference beam pattern). The accuracy of the phase and amplitude adjustment determines the deviation and resolution of the beam angle. Summary of the Invention

[0003] In one aspect of the present invention, there is provided a coupler device for a phased array system. The coupler device includes an adjustable amplifier and a coupler. The adjustable amplifier is configured to convert an input signal into a first intermediate signal and a second intermediate signal. The coupler is coupled to the adjustable amplifier. The coupler includes: a first input port that receives the first intermediate signal; a second input port that receives the second intermediate signal; a first output port that outputs a first output signal; and a second output port that outputs a second output signal. A phase difference between a first phase of the first intermediate signal and a second phase of the second intermediate signal is a fixed phase angle.

[0004] In another aspect of the present invention, there is provided a coupler device for a phased array system. The coupler device includes: a power divider configured to divide an input signal to generate a first signal and a second signal; a first balun configured to convert the first signal to generate an inverted first signal; a second balun configured to convert the second signal to generate an inverted second signal; a first variable gain amplifier configured to amplify the inverted first signal to generate a third signal; a second variable gain amplifier configured to amplify the inverted second signal to generate a fourth signal; and a coupler coupled to the first variable gain amplifier and the second variable gain amplifier, wherein the coupler includes: a first input port that receives the third signal; a second input port that receives the fourth signal; a first output port that outputs a fifth signal; and a second output port that outputs a sixth signal. Brief Description of the Drawings

[0005] Aspects of the present invention are best understood from the following [Embodiments] when read in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practice in the industry, various components are not drawn to scale. In fact, for clarity of discussion, the dimensions of various components may be arbitrarily increased or decreased.

[0006] FIG. 1 is a block diagram of a phased array system 1 according to an embodiment of the present invention.

[0007] FIG. 2A is a block diagram of a phased array system 2 according to an embodiment of the present invention.

[0008] FIG. 2B is a block diagram of a coupler device of the embodiment of FIG. 2A.

[0009] FIG. 2C is a schematic diagram showing output signals B and C of FIG. 2B plotted on a complex plane.

[0010] FIG. 2D is a schematic diagram of an adjustable amplifier of FIG. 2B.

[0011] FIG. 2E is a schematic diagram of a small signal model of a BJT of FIG. 2D.

[0012] FIG. 2F is a schematic diagram of a small signal model of the adjustable amplifier of FIG. 2D.

[0013] FIG. 2G is another schematic diagram of a small signal model of the adjustable amplifier of FIG. 2D.

[0014] FIG. 2H is a schematic diagram showing the phase control of the phase array system 2 according to the embodiment of FIG. 2A.

[0015] FIG. 3 is a block diagram of a coupler device 300 according to another embodiment of the present invention.

[0016] FIG. 4 is a block diagram of a coupler device according to another embodiment of the present invention.

[0017] FIG. 5A is a schematic diagram showing a power divider according to an embodiment of the present invention.

[0018] FIG. 5B is a schematic diagram showing a power divider according to another embodiment of the present invention.

[0019] FIG. 6 is a schematic diagram showing a Marchand balun according to an embodiment of the present invention. Embodiments

[0020] The following disclosure provides many different embodiments or examples for implementing the various components of the provided subject matter. Specific examples of operations, components, and configurations are described below to simplify the present invention. Of course, these are only examples and are not intended to be limiting. For example, in the description, performing a first operation before or after a second operation may include embodiments in which the first and second operations are performed together, and may also include embodiments in which additional operations may be performed between the first and second operations. For example, in the following description, forming a first member above, on, or within a second member may include embodiments in which the first and second members are formed in direct contact, and may also include embodiments in which additional members may be formed between the first and second members such that the first and second members are not in direct contact. Additionally, the present invention may repeat reference numerals and / or letters in various examples. This repetition is for simplicity and clarity purposes and does not itself prescribe a relationship between the various embodiments and / or configurations discussed.

[0021] For ease of description, time relative terms such as "before", "prior to", "after", "post-" and the like may be used herein to describe the relationship of one operation or component to another operation or component, as illustrated in the figures. Time relative terms are intended to encompass different sequences of operations depicted in the figures. Additionally, for ease of description, spatial relative terms such as "beneath", "under", "below", "above", "over" and the like may be used herein to describe the relationship of one element or component to another element or component, as illustrated in the diagrams. Spatial relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. The device may be oriented otherwise (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein may be interpreted accordingly. For ease of description, connection relative terms such as "connect", "connected", "connection", "coupled", "coupled to", "in communication with" and the like may be used herein to describe an operative connection, coupling or linkage between two elements or components. Connection relative terms are intended to encompass different connections, couplings or linkages of the device or assembly. The device or assembly may be directly or indirectly connected, coupled or linked to each other, for example, through another set of components. The device or assembly may be connected, coupled or linked to each other both wired and / or wirelessly.

[0022] As used herein, the singular terms "a", "an" and "the" may include plural references, unless the context clearly indicates otherwise. For example, a reference to a device may include multiple devices, unless the context clearly indicates otherwise. The terms "comprising" and "including" may indicate the presence of the described features, integers, steps, operations, elements and / or components, but do not preclude the presence of one or more combinations of features, integers, steps, operations, elements and / or components. The term "and / or" may include any or all combinations of one or more of the listed items.

[0023] Additionally, quantities, ratios and other numerical values are sometimes presented herein in a range format. It should be understood that this range format is used for convenience and brevity and should be interpreted flexibly to include the values explicitly specified as limits of the range, but also to include all individual values or sub-ranges subsumed within that range, as if each value and sub-range were explicitly specified.

[0024] The nature and use of the embodiments are discussed in detail below. However, it should be understood that the present invention provides many applicable inventive concepts that can be embodied in various specific contexts. The specific embodiments discussed merely illustrate specific ways of embodying and using the present invention and do not limit its scope.

[0025] FIG. 1 is a block diagram of a phase array system 1 according to an embodiment of the present invention. The phase array system 1 may include a power distribution network 10, a plurality of phase shifters 21 (i.e., represented by the symbol φ), a plurality of variable gain amplifiers 22, and a plurality of amplifiers 23. For purposes of description, there are 8 output paths of the power distribution network 10, each of which corresponds to a respective phase shifter 21, a respective variable gain amplifier 22, and a respective amplifier 23. The phase array system 1 may receive an input signal A distributed to each of the phase shifters 11 through the power distribution network 10. For example, the power distribution network 10 may include a plurality of power dividers 12, each of which may be configured to equally distribute the input power at two output ports. Therefore, the input signal A may be equally distributed to 8 output signals A1 to A8 by the power dividers 12 in the power distribution network 10, and the output signals A1 to A8 are fed to the respective phase shifters 21.

[0026] In some embodiments, the phase shifters 21 may be digitally controlled phase shifters, each of which may be configured to convert the phase of an input signal (e.g., A1 to A8) according to a respective control parameter (not shown in FIG. 1) to generate an output signal having a respective preset phase. The phase shifters 21 may electronically vary the phase in a progressive and repetitive manner between 0° and 360° to generate a specific scanning pattern. The output signals of each phase shifter 21 may be amplitude weighted by a respective variable gain amplifier (VGA) 22, and the amplitude weighted signals are amplified by the respective amplifiers 23 to generate the desired output signals (e.g., B1 to B8). The output signals B1 to B8 may be radiated by respective antennas (not shown in FIG. 1), thereby synthesizing different beam conditions.

[0027] However, due to the architecture of the phase array system 1, there may be three stages of the power dividers 12 in the power distribution network 10, and each stage may cause a 3 dB power loss when dividing the input signal into two output signals. If more antennas are used by the phase array system 1, there will be more stages of the power dividers 12 in the power distribution network 10, resulting in a greater power loss of the output signals of the power distribution network. For example, if 8 antenna elements are used, there may be a 3 dB * 3 = 9 dB power loss for each of the output signals A1 to A8 of the power distribution network. If a target output power is 20 dB, the amplifiers 23 at the output stage may need a high gain of more than 29 dB to compensate for the signal loss of the power distribution network 10.

[0028] FIG. 2A is a block diagram of a phase array system 2 according to an embodiment of the present invention. FIG. 2B is a block diagram of a coupler device 202 according to the embodiment of FIG. 2A. FIG. 2C is a schematic diagram showing output signals B and C plotted on a complex plane according to the embodiment of FIG. 2B. Please refer to FIGS. 2A to 2C.

[0029] In some embodiments, the phase array system 2 may include a weighting network 200. The weighting network 200 may include a plurality of coupler devices 202. For purposes of description, eight output signals B1 to B8 are generated by the weighting network 200 of the phase array system 2, and the coupler devices 202 may be configured in 3 stages of a cascaded architecture, but the present invention is not limited thereto. The output signals B1 to B8 may be radiated by respective antennas (not shown in FIG. 2A), thereby synthesizing different beam patterns.

[0030] For example, the coupler device 202 may be configured to amplify the input signal A, reconfigure the power ratio, and adjust the amplitude and / or phase of the output signals at each path to respective amplifiers 204 to generate the desired output signals to synthesize different beam patterns. The output signals (e.g., A1 to A8) at each path of the weighting network 200 may be sent to respective amplifiers 204 at the output stage, and the amplified output signals at each path may be radiated by respective antennas (not shown in FIG. 2A). In some other embodiments, the output signals (e.g., A1 to A8) at each path of the weighting network 200 may be sent to respective phase inverters 203. The inverted output signals at each path may be sent to respective amplifiers 204 at the output stage, and the amplified output signals at each path may be radiated by respective antennas (not shown in FIG. 2A).

[0031] Referring to FIG. 2B, the coupler device 202 may include a tunable amplifier 2021 and a coupler 2022. The tunable amplifier 2021 may be configured to control the gains of the intermediate signals a1 and a2 respectively based on the input signal A. The coupler 2022 may be configured to generate output signals B and C based on the intermediate signals a1 and a2. Specifically, each of the coupler devices 202 shown in FIG. 2A may be configured to control the phase difference between one of its two output signals B and C to a fixed phase angle φ, which can be expressed by the following formula (1). Phase(B) - Phase(C) = φ (1)

[0032] In addition, the relationship between the input signal A and the phases of the output signals B and C can be expressed by the following formula (2).

[0033] In some embodiments, the coupler 2022 can be a substantially 90° hybrid coupler, having two input ports P1 to P2 and two output ports P3 to P4. Two paths (i.e., two transmission lines) couple each input port to the two output ports P3 to P4. For example, a first transmission line can be coupled between the input port P1 and the output port P3, a second transmission line can be coupled between the input port P1 and the output port P4, a third transmission line can be coupled between the input port P2 and the output port P3, and a fourth transmission line can be coupled between the input port P2 and the output port P4.

[0034] The output signals B and C can be a linear combination of the intermediate signals a1 and a2. For example, a first part of the output signal B can come from the intermediate signal a1, which is directly transmitted from the input port P1 to the output port P3 through a first transmission line, and a second part of the output signal B can come from the intermediate signal a2, which is transmitted from the input port P2 to the output port P3 with a substantially 90° phase shift through a second transmission line. Therefore, the output signal B (i.e., vector B) can be expressed by the following formula (3).

[0035] Similarly, a first part of the output signal C can come from the intermediate signal a2, which is directly transmitted from the input port P2 to the output port P4, and a second part of the output signal C can come from the intermediate signal a1, which is transmitted from the input port P1 to the output port P4 with a substantially 90° phase shift. Therefore, the output signal C (i.e., vector C) can be expressed by the following formula (4).

[0036] Therefore, the output signals B and C can be plotted on a complex plane as shown in FIG. 2C. It should be noted that there is an included angle φ that separates the output signals B and C. The adjustable amplifier 2021 can adjust a first gain and a second gain of the input signal A so as to control the amplitude values of the signals a1 and a2 respectively, thereby also controlling the included angle φ shown in formula (1).

[0037] FIG. 2D is a schematic diagram of an adjustable amplifier 2021 according to an embodiment of FIG. 2B. FIG. 2E is a schematic diagram of a small-signal model of a BJT according to an embodiment of FIG. 2D. FIG. 2F is a schematic diagram of a small-signal model of the adjustable amplifier 2021 according to an embodiment of FIG. 2D. FIG. 2G is another schematic diagram of the small-signal model of the adjustable amplifier 2021 according to an embodiment of FIG. 2D. Please refer to FIGS. 2B and 2D to 2G.

[0038] A schematic diagram of the adjustable amplifier 2021 is shown in FIG. 2D. In some embodiments, bipolar junction transistors BJT A and BJT B may respectively have control voltages Vbb A and Vbb B. Additionally, the bipolar junction transistors BJT A and BJT B may be biased using large capacitors Cb and resistors Rbb. The values of the capacitors Cb and resistors Rbb may be large enough such that the components shown in FIG. 2D can be used as a bias network and can be omitted from RF small-signal analysis. The bases of the bipolar junction transistors BJT A and BJT B may be connected to node N1, and the base currents Ib A and Ib B of the bipolar junction transistors BJT A and BJT B may be independently controlled by the control voltages Vbb A and Vbb B.

[0039] An input matching network 210 may be applied to match the impedance of the shunt bipolar junction transistors BJT A and BJT B to the system impedance. The output matching networks 220A and 220B may be substantially the same and may be applied to the output ports of the bipolar junction transistors BJT A and BJT B to match the output impedance of the bipolar junction transistors BJT A and BJT B to the system impedance Z 0. Additionally, the output matching networks 220A and 220B may be configured to provide the bias currents Ic A and Ic B of the bipolar junction transistors BJT A and BJT B.

[0040] A small-signal model of a bipolar junction transistor (e.g., BJT A or BJT B in FIG. 2D) is shown in FIG. 2E, where CI and CO may respectively represent the equivalent capacitances at the base and collector nodes. The gain of a BJT with conjugate-matched source / load impedance (G BJT,M) can be evaluated using Equation (5) below.

[0041] where r π represents the input resistance of the BJT, r o represents the output resistance of the BJT, and β represents the current gain of the BJT. Additionally, by applying the relationship between the parameters r π, Ic, and Ib (e.g., And \(I_c = \beta I_b\), Equation (5) can be rewritten as Equation (6) below.

[0042] Referring to the small-signal model of the tunable amplifier 2021 shown in FIG. 2F, the input resonant capacitor can be incorporated into the input matching network 210 and the output matching networks 220A to 220B as the source network and the load network, because the input nodes of the bipolar junction transistors BJT A and BJT B are shunted. Therefore, the small-signal model of the tunable amplifier 2021 can be simplified to two current-controlled current sources connected to a source network 230 and two load networks 240A to 240B. The simplified small-signal model of the tunable amplifier 2021 is shown in FIG. 2G.

[0043] In some embodiments, the link budget of the phased array system 2 shown in FIG. 2A can be associated with the total power of the signal. The input signal A can be distributed and weighted by the coupler device 202 in the weighting network 200 to obtain signals A1 to A8. The signals A1 to A8 can be amplified by the respective amplifiers 204 at the output stage. Since the coupler 2022 of the coupler device 202 can be a lossless and passive component, the link budget of the phased array system 2 can be associated with the stage of the coupler device.

[0044] Referring to FIG. 2G, the input resistance \(r_{\pi A}\) of the bipolar junction transistor BJT A can be expressed as a function of the collector current \(I_{CA}\) (for example, and ), and the input resistance of the bipolar junction transistor BJT B can be expressed as a function of the collector current \(I_{CB}\) (for example, and ). With this design of the tunable amplifier 2021, the gains of the output signals at the output ports Port2 and Port3 of the tunable amplifier 2021 can be independently controlled. Therefore, the tunable amplifier 2021 can be equivalent to an ideal power divider with an amplifier to achieve the functions of power saving and signal amplification.

[0045] Figure 2H illustrates the phase control of the phase array system 2 according to the embodiment of Figure 2A. As described in the embodiment of Figure 2C, the phase difference between the output signals B and C can be controlled by adjusting the gains of the output signals B and C of the coupler device 202 using the adjustable amplifier 2021. The coupler device 202 can also have the function of phase shift. Therefore, the coupler device 202 can be appropriately configured such that the phase difference of the output signals of each coupler device 202 can be horizontal and vertical. For example, regarding the coupler device 202 receiving the input signal A, a first-stage phase difference Δφ1x can be horizontal (i.e., the X-axis). For the coupler device 202 in the second stage, a second-stage phase difference Δφ2y can be vertical (i.e., the Y-axis). For the coupler device 202 in the third stage, a third-stage phase difference Δφ3x can be horizontal (i.e., the X-axis), as shown in Figure 2H.

[0046] Figure 3 is a block diagram of a coupler device 300 according to another embodiment of the present invention.

[0047] In some embodiments, the coupler device 202 shown in Figure 2A can be implemented by the coupler device 300 shown in Figure 3. The coupler device 300 can include a power divider 302, variable gain amplifiers 304 and 306, and a coupler 308.

[0048] The power divider 302 can be a 1-to-2 passive power divider configured to divide an input signal A into two signals A1 and A2. The signals A1 and A2 can be amplified by the variable gain amplifiers 304 and 306 to obtain intermediate signals a1 and a2 respectively. The gains of the variable gain amplifiers 304 and 306 can be independently controlled. The coupler 308 can be similar to the coupler 2022 shown in Figure 2B, and its details are not repeated here.

[0049] For power saving, the power divider 302 can cause a 3 dB signal loss of the input signal A. As the number of stages of the power divider 302 increases, the signal loss in the phase array system increases accordingly. For example, three stages of the coupler device 202 are shown in Figure 2A. Using the coupler device 300 as the coupler device 202 results in a 9 dB signal loss. If a design with 64 antenna elements is used, the coupler device 300 will have 6 stages, which will result in a signal loss of 3 dB * 6 = 18 dB. In addition, the generated signal loss can be compensated by the amplifier 204 at the output stage. If the output power requirement is 20 dB, the amplifier 204 at the output stage needs a very high gain of 38 dB, which may have the risk of signal oscillation.

[0050] FIG. 4 is a block diagram of a coupler device according to yet another embodiment of the present invention. Referring to FIGS. 2A and 4.

[0051] In another embodiment, the coupler device 202 shown in FIG. 2A can be implemented using the coupler device 400 shown in FIG. 4. The coupler device 400 can be a 1-to-2 coupler device, which includes a power splitter 402, a balun (balanced-to-unbalanced) 404, a switch 406, a variable gain amplifier 408, a coupler 410, and an amplifier 412, as shown in FIG. 4.

[0052] In some embodiments, the power splitter 402 can be a three-port microwave device for power distribution or power combination. The power splitter 402 can be a 1-to-2 passive power splitter configured to divide an input signal A into two signals a1 and a2. In some embodiments, the power splitter 402 can be implemented by a T-junction power splitter 500a shown in FIG. 5A, which is a three-port network that can be implemented in any type of transmission medium (such as a microstrip line, a stripline, a coplanar waveguide, etc.). In some embodiments, the microstrip line 502 can have a characteristic impedance value of approximately equal to 50 ohms, and the microstrip lines 504 and 506 can have characteristic impedance values of approximately equal to 100 ohms, but the present invention is not limited thereto.

[0053] In some embodiments, the power splitter 402 can be implemented by a Wilkinson power splitter 500b shown in FIG. 5B. The Wilkinson power splitter 500b can be a robust power splitter with matched output ports and dissipating reflected power, and can provide better isolation between the output ports N2 and N3 compared to the T-junction power splitter 500a shown in FIG. 5A. The Wilkinson power splitter 500b can also be used to provide any power distribution. In some embodiments, the microstrip line 512 can have a characteristic impedance value of approximately equal to 50 ohms, and the microstrip lines 514 and 516 can have characteristic impedance values substantially equal to 70.7 ohms. The microstrip lines 518 and 520 can have characteristic impedance values substantially equal to 50 ohms, and the resistor R1 can have a resistance value substantially equal to 100 ohms, but the present invention is not limited thereto.

[0054] In some embodiments, each of the baluns 404 may be referred to as a balun device, which is configured to provide its input signal and an inverted input signal at its two output terminals. For example, the balun 404 on the left side of FIG. 4 may receive the signal a1 as the input signal, and it may provide the signal a1 and the inverted signal -a1 at its two output terminals. Similarly, the balun 404 on the right side of FIG. 4 may receive the signal a2 as its input signal, and it may provide the signal a2 and the inverted signal -a2 at its two output terminals. In some embodiments, the balun 404 may be implemented using the Marchand balun 600 shown in FIG. 6, which is a broadband 3-port network including two sets of coupled lines (602 and 606, 604 and 608). Each set of coupled lines may have a length substantially equal to λ / 4, where λ represents the wavelength of the radio frequency signal used by the phased array system 2 shown in FIG. 2A.

[0055] Referring to FIG. 6, Port1 refers to an unbalanced port, and Port2 and Port3 refer to balanced ports. In the configuration of the coupler device 400 in FIG. 4, the input signal A1 is fed to the unbalanced port Port1 of the balun 404 on the left side, and signals A1 and -A1 can be generated at the balanced ports Port2 and Port3. Additionally, the input signal A2 is fed to the unbalanced port Port1 of the balun 404 on the right side, and signals A2 and -A2 can be generated at the balanced ports Port2 and Port3. In other words, the balanced port Port2 can provide an output signal having a zero phase difference from the input signal, and the balanced port Port3 can provide an output signal having a 180-degree phase difference from the input signal (i.e., the inverted input signal).

[0056] Now turning back to FIG. 4. In some embodiments, the switch 406 may be implemented using a series single-pole double-throw (SPDT) switch or a series-shunt SPDT switch, but the present invention is not limited thereto. In the configuration of the coupler device 400 in FIG. 4, the signal S1 may be the inverted signal A1 (i.e., -A1), and the signal S2 may be the inverted signal A2 (i.e., -A2). It should be noted that the signal selection of the switch 406 may be based on the design of the coupler device, and in some other embodiments, the signals S1 and S2 may be the signals A1 and A2.

[0057] In some embodiments, each of the variable gain amplifiers 408 can be a three-stage amplifier that includes a common-gate (CG) amplifier, a common-source (CS) amplifier, and a common-drain (CD) amplifier connected in series. The common-gate amplifier can be used as an input stage, the common-source amplifier can be used as a gain stage, and the common-drain amplifier can be used as an output stage. In some embodiments, a variable resistor (not shown) can be disposed between the common-gate amplifier and the common-source amplifier to adjust the gain of the common-source amplifier. In the configuration of the coupler device 400 shown in FIG. 4, the variable gain amplifier 408 can be configured to amplify signals S1 and S2 to generate signals a1 and a2.

[0058] In some embodiments, the coupler 410 can be implemented using a branch coupler or a coupled-line coupler, but the present invention is not limited thereto. For example, the coupler 410 can receive signals a1 and a2 to generate signals b1 and c1. In some embodiments, the coupler 410 can be similar to the coupler 2022 shown in FIG. 2B, and the details can be mentioned in the embodiments of FIG. 2B.

[0059] In some embodiments, each of the amplifiers 412 can also be a three-stage amplifier that includes a common-gate (CG) amplifier, a common-source (CS) amplifier, and a common-drain (CD) amplifier connected in series. The common-gate amplifier can be used as an input stage, the common-source amplifier can be used as a gain stage, and the common-drain amplifier can be used as an output stage. Compared with the variable gain amplifier 408, the gain of the amplifier 412 can be fixed to compensate for the signal loss caused by the passive components (such as the power divider 402, the balun 404, and the switch 406) in the coupler device 400. In the configuration of the coupler device 400 shown in FIG. 4, the amplifier 412 can be configured to amplify signals a1 and a2 to generate output signals B and C. In some embodiments, the amplifier 412 can be omitted in the coupler device 400, and other amplifiers (such as the amplifier 204) can be disposed at the output stage of each path of the phased array system 2 shown in FIG. 2A.

[0060] Although the present invention has been described with specific embodiments of the present invention, it is obvious that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, various components of the embodiments can be interchanged, added, or replaced in other embodiments. Moreover, all the elements of each figure are not necessary for the operation of the disclosed embodiments. For example, by simply adopting the elements of the independent claims, those of ordinary skill in the art will be able to make and use the teachings of the present invention. Therefore, the embodiments of the present invention as set forth herein are intended to be illustrative rather than restrictive. Various changes can be made without departing from the spirit and scope of the present invention.

[0061] Even though many features and advantages of the present invention, as well as details of its structure and function, have been set forth in the foregoing description, the invention is illustrative only. Within the principles of the present invention, changes may be made in details, especially in regard to the shape, size, and arrangement of parts, until the full scope indicated by the broad general meaning of the terms used in the appended claims for the invention is reached.

[0062] 1: Phase array system 2: Phase array system 10: Power distribution network 12: Power divider 21: Phase shifter 22: Variable gain amplifier 23: Amplifier 200: Weighting network 202: Coupling device 203: Phase inverter 204: Amplifier 210: Input matching network 220A: Output matching network 220B: Output matching network 230: Source network 240A: Load network 240B: Load network 300: Coupling device 302: Power divider 304: Variable gain amplifier 306: Variable gain amplifier 308: Coupler 400: Coupling device 402: Power divider 404: Balun 406: Switch 408: Variable gain amplifier 410: Coupler 412: Amplifier 500a: T-junction power divider 500b: Wilkinson power divider 502: Microstrip line 504: Microstrip line 506: Microstrip line 512: Microstrip line 514: Microstrip line 516: Microstrip line 518: Microstrip line 520: Microstrip line 600: Marchand balun 602: Coupled line 604: Coupled line 606: Coupled line 608: Coupled line 2021: Tunable amplifier 2022: Coupler P1: Input port P2: Input port P3: Output port P4: Output port

Claims

1. A coupler device for a phase array system, the coupler device comprising: A power divider configured to divide an input signal to generate a first signal and a second signal; a first balun configured to convert the first signal to generate an inverted first signal; a second balun configured to convert the second signal to generate an inverted second signal; a first variable gain amplifier configured to amplify the inverted first signal to generate a third signal; a second variable gain amplifier configured to amplify the inverted second signal to generate a fourth signal; and a coupler coupled to the first and second variable gain amplifiers, wherein the coupler includes: a first input port for receiving the third signal; a second input port for receiving the fourth signal; a first output port for outputting a fifth signal; and a second output port for outputting a sixth signal.

2. The coupler device of claim 1, wherein a fixed phase angle exists between a first phase of one of the fifth signals and a second phase of one of the sixth signals.

3. The coupler device of claim 2, wherein the fixed phase angle is changed by adjusting a first gain of one of the inverted first signals and a second gain of one of the inverted second signals.

4. The coupler device as claimed in claim 1, further comprising: A first switch coupled between the first balun and the first variable gain amplifier, and configured to select between the first signal and the inverted first signal output by the first balun; and a second switch coupled between the second balun and the second variable gain amplifier, and configured to select between the second signal and the inverted second signal output by the second balun.

5. The coupler device of claim 1, wherein the first variable gain amplifier and the second variable gain amplifier are implemented by a three-stage amplifier, the three-stage amplifier comprising an input stage, a gain stage and an output stage connected in series.

6. The coupler device of claim 5, wherein the input stage includes a common-gate amplifier, the gain stage includes a common-source amplifier, and the output stage includes a common-drain amplifier.

7. The coupler arrangement of claim 6, wherein a variable resistor is disposed between the input stage and the gain stage to adjust the gain of one of the gain stages.

8. The coupler device as claimed in claim 1, wherein the coupler is a 90-degree hybrid coupler.

9. The coupler device of claim 1, wherein the first balun and the second balun are Marchand baluns.

10. The coupler device as claimed in claim 1, wherein the power divider is a Wilkinson power divider.

11. The coupler device of claim 10, wherein the Wilkinson power divider includes two sets of coupling lines, each set of coupling lines having a length of λ / 4, where λ represents a wavelength of a radio frequency signal used by the phase array system.

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