New broadband balun structure and application thereof

Abstract

Provided in the present invention are a new broadband Balun structure and the application thereof. The new broadband Balun structure comprises an inverting transformer and an autotransformer, wherein the inverting transformer inverts an input signal to generate an inverted signal; the autotransformer performs voltage division on the input signal to generate an in-phase signal; one end of the inverting transformer and / or the autotransformer is connected to a signal of an unbalanced end; and the other end of the inverting transformer serves as an inverted signal end of a balanced end, and the other end of the autotransformer serves as an in-phase signal end of the balanced end. An in-phase signal is generated from an input signal by means of a voltage division function, and an inverted signal is generated by an inverting transformer, such that the structure is simple and the parasitic capacitance is low; and the inverting transformer and an autotransformer can each be optimized to achieve an amplitude and phase balance within a broadband, and the two transformers can each be vertically coupled, such that the size is smaller. By adjusting an inductance ratio of the inverting transformer to the autotransformer, Balun structures with different impedance ratios can be implemented over a very wide bandwidth, and an excellent amplitude and phase balance can be achieved.

Description

A new broadband balun structure and its application Technical Field

[0001] The present invention relates to the field of balun bandwidth technology, and in particular to a novel broadband balun structure and its application. Background Art

[0002] Baluns are essential components for converting single-ended signals into balanced signals and are widely used in RF, microwave, and millimeter-wave wireless and radio communications, instrumentation, and measurement systems. Key balun performance metrics include insertion loss, amplitude / phase balance, and chip size. Wide bandwidth is crucial for broadband applications such as instrumentation, measurement systems, broadband detection systems, and high-speed ADCs.

[0003] There are many different balun structures, including transformer-based baluns (voltage-type baluns), current-type baluns (GUANELLA-type baluns), Marchand baluns, Ruthroff-type baluns, and autotransformer-based baluns. As shown in Figure 1, the bandwidth of a transformer balun is limited by the non-inverting transformer, which results in phase and amplitude imbalances due to parasitic capacitance between the primary and secondary windings. The GUANELLA-type balun offers excellent bandwidth. Integer impedance ratio baluns can be achieved by connecting multiple basic 1:1 GUANELLA baluns (as shown in Figure 2) in series and parallel (a 4:1 balun is shown in Figure 3). However, this type of balun topology has several limitations: 1. Fractional impedances are difficult to achieve; 2. Beyond integer impedance ratios of 1:1 and 1:4, the topology is complex. The Marchand balun is widely used as a broadband balun, but its bandwidth is inherently limited by the quarter-wavelength transmission line required in its topology. Transmission line structures are primarily used in microwave and millimeter-wave applications. Autotransformer-type baluns. The Ruthroff 1:1 Balun has a wider bandwidth than all other previous balun topologies, but it can only achieve a 1:1 impedance value.

[0004] It can be seen that the existing balun structure is either too complex or too stereotyped, and the impedance transformation ratio is limited to integer values ​​and cannot be flexibly transformed. To solve the above problems, the present invention provides a new balun topology structure.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to solve at least one of the technical defects. The novel balun topology structure and its application proposed in the present invention realize broadband and flexible impedance transformation.

[0007] One object of the present invention is to provide a novel broadband balun structure capable of impedance transformation, the structure comprising an inverting transformer and an autotransformer; the inverting transformer is used to invert an unbalanced end signal to generate an inverted signal; the autotransformer is used to divide the unbalanced end signal to generate a non-inverted signal; one end of the inverting transformer and / or the autotransformer is connected to the unbalanced end signal; when one end of the inverting transformer or the autotransformer is connected to the unbalanced end input signal, the inverting transformer is connected to the autotransformer;

[0008] The other end of the inverting transformer serves as an inverting signal port of the balanced end, and the other end of the autotransformer serves as a non-phase signal port of the balanced end.

[0009] Further preferably, the inverter transformer includes a first inductor L1 and a second inductor L2 coupled together; the autotransformer includes a third inductor L3 and a fourth inductor L4; wherein the first inductor L1 and the second inductor L2 are coupled to each other via a magnetic field; the third inductor L3 and the fourth inductor L4 are coupled to each other via a magnetic field; the first inductor L1 and the second inductor L2 are connected in the manner of an inverter transformer, and the third inductor L3 and the fourth inductor L4 are connected in the manner of an autotransformer. One end of the autotransformer is connected to one end of the inverter transformer.

[0010] Further preferably, the inverting transformer includes a first inductor L1 and a second inductor L2 coupled together; the autotransformer includes a third inductor L3 and a fourth inductor L4; one end of the first inductor L1 of the inverting transformer is connected to the unbalanced end, and the other end is connected to the third inductor L3; the second inductor L2 and the opposite-name end of the first inductor L1 are connected to the inverting port of the balanced end, and are grounded with the same-name end of the first inductor L1; the other end of the third inductor L3 is connected to the same-name port of the balanced end, the other end of the third inductor L3 is connected to one end of the fourth inductor L4, and the other end of the fourth inductor L4 is grounded.

[0011] Further preferably, the inverting transformer includes a first inductor L1 and a second inductor L2 coupled together; the autotransformer includes a third inductor L3 and a fourth inductor L4; one end of the first inductor L1 is connected to the unbalanced end, the second inductor L2 and the opposite-name end of the first inductor are connected to the inverting port of the balanced end, and the second inductor L2 and the same-name end of the first inductor L1 are grounded; one end of the third inductor L3 is connected to the other end of the first inductor L1 and one end of the fourth inductor L4, and the other end of the third inductor L3 is connected to the same-name port of the balanced end; the other end of the fourth inductor L4 is grounded.

[0012] Further preferably, the inverting transformer includes a first inductor L1 and a second inductor L2 coupled together; the autotransformer includes a third inductor L3 and a fourth inductor L4; the third inductor L3 is connected to the fourth inductor L4 and serves as a port of the unbalanced end, the other end of the fourth inductor L4 is grounded, the other end of the third inductor L3 is connected to one end of the first inductor L1, the other end of the first inductor L1 serves as the in-phase port of the balanced end, the first inductor L1 is coupled to the second inductor L2, the second inductor L2 and the first inductor L1 have the same-name end grounded, and the other end of the second inductor L2 is connected to the inverting port of the balanced end.

[0013] Further preferably, the method further includes connecting a fifth inductor L5 to the in-phase output end, wherein one end of the fifth inductor L5 is connected to the in-phase port of the balanced end, and the other end is grounded.

[0014] Further preferably, the inductance centers of the inverter transformer and the autotransformer are embedded in magnetic core materials.

[0015] Further preferably, the inductors of the inverter transformer and the autotransformer are planar single-layer or multi-layer inductor structures in an integrated circuit process or a LTCC process.

[0016] Further preferably, the unbalanced end is high impedance and the balanced end is low impedance. In the inverter transformer, the impedance ratio of the first inductor L1 and the second inductor L2 is L1 / L2=n:1, where n can be an integer or a fraction. The ratio of the inductor L3 of the autotransformer to the total inductance formed by L3 and L4 is 1:n. The impedance ratio of the unbalanced end to the balanced end of the balun is n:1.

[0017] Further preferably, the unbalanced end is low resistance, the balanced end is high resistance, the impedance ratio of the first inductor L1 and the second inductor L2 is L1 / L2=1:n, the ratio of the inductance L3 of the autotransformer to the total inductance formed by L3 and L4 is 1:n, and the impedance ratio of the unbalanced end to the balanced end of the balun is 1:n.

[0018] The present invention also provides an application of a novel broadband balun structure for a push-pull amplifier, a high IIP2 amplifier, or a high linearity amplifier; the application comprises two of the novel broadband balun structures described above, wherein the in-phase output end and the inverting output end of one of the impedance transformation balun structures are respectively connected to an amplifier, and the output ends of the two amplifiers are connected to another impedance transformation balun structure.

[0019] The present invention also provides an application of a novel broadband balun structure for a broadband high-linearity mixer, comprising two of the above-mentioned novel broadband balun structures, wherein the in-phase output and the inverting output of one of the impedance transformation balun structures are connected to the mixer, and the output of the mixer is connected to another impedance transformation balun structure.

[0020] The novel broadband balun structure and its application provided according to the embodiments of the present invention have at least the following advantages over existing balun structures:

[0021] The in-phase signal of the balun structure provided in the present application is generated by the unbalanced end signal through the voltage divider function, which keeps it in phase with the input signal; the inverted signal is generated by the inverting transformer, which has a simple structure and less parasitic capacitance. The inverting transformer and the autotransformer can be vertically coupled, so the size is smaller, and excellent amplitude and phase balance can be achieved over a very wide bandwidth. When used in a balanced mixer and a push-pull amplifier, a better common-mode suppression effect can be achieved.

[0022] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0024] FIG1 is a structural diagram of the balun of the transformer mentioned in the background art;

[0025] FIG2 is a structural diagram of the current-mode balun mentioned in the background art;

[0026] FIG3 is a structural diagram of another current-type balun mentioned in the background art;

[0027] FIG4 is a schematic structural diagram of a novel broadband balun structure shown in one embodiment of the present application;

[0028] FIG5 is a schematic structural diagram of a novel broadband balun structure shown in another embodiment of the present application;

[0029] FIG6 is a schematic structural diagram of a novel broadband balun structure shown in another embodiment of the present application;

[0030] FIG7 is a circuit connection structure of a novel broadband balun structure shown in an embodiment of the present application;

[0031] FIG8 is a circuit connection structure of a novel broadband balun structure shown in another embodiment of the present application;

[0032] FIG9 is a circuit connection structure of a novel broadband balun structure shown in another embodiment of the present application;

[0033] FIG10 is a circuit connection structure of a novel broadband balun structure shown in another embodiment of the present application. DETAILED DESCRIPTION

[0034] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0035] As shown in Figures 4-6, the embodiments of the present invention propose a new broadband balun structure, including an inverting transformer and an autotransformer; the balun can be used to convert an unbalanced signal (single-ended signal) into a balanced signal (differential signal), and can also convert a balanced signal (differential signal) into an unbalanced signal (single-ended signal). The following takes the conversion of a single-ended signal to a differential signal as an example: the unbalanced end is the input end, and the balanced end is the output end. The inverting transformer is used to invert the signal at the unbalanced end to generate an inverted signal; the autotransformer is used to divide the input signal to generate a non-inverted signal;

[0036] Among them, Figure 4 shows that one end of the inverter transformer is connected to the unbalanced end; Figure 5 shows that the autotransformer is connected to the unbalanced end; when one end of the inverter transformer or the autotransformer is connected to the unbalanced end, the inverter transformer is connected to the autotransformer; Figure 6 shows that the inverter transformer and the autotransformer are connected to the unbalanced end at the same time.

[0037] The other end of the inverting transformer serves as the inverting end of the balanced end, and the other end of the autotransformer serves as the non-inverting end of the balanced end.

[0038] As shown in Figure 7, the first inductor L1 and the second inductor L2 are coupled to each other via a magnetic field; the third inductor L3 and the fourth inductor L4 are coupled via a magnetic field. The first inductor L1 and the second inductor L2 are connected in the manner of an inverting transformer, while the third inductor L3 and the fourth inductor L4 are connected in the manner of an autotransformer. One end of the autotransformer is connected to one end of the inverting transformer. Specifically, one end of the first inductor L1 serves as an input end, and the other end is connected to the third inductor L3. One end of the second inductor L2 serves as an inverting output end and is grounded with the opposite-phase end of the first inductor L1. The other end of the third inductor L3 serves as a non-inverting output end and is connected to one end of the fourth inductor L4, the other end of which is grounded.

[0039] At this point, the unbalanced end (P1) has high impedance, while the balanced ends (P2 and P3) have low impedance. L1 > L2. For example, if L1 / L2 = 4:1 in the inverter transformer, L3 = L4 in the autotransformer, and K1 = K2 = 1, the impedance ratio of the unbalanced end to the balanced end of this balun is 4:1. When L3 = L4 and L1 = 0, the balun transforms into a Ruthroff 1:1 balun.

[0040] As shown in FIG. 8, the inverter transformer includes a first inductor L1 and a second inductor L2 which are coupled; the autotransformer includes a third inductor L3 and a fourth inductor L4; one end of the first inductor L1 is connected to the unbalanced terminal, one end of the second inductor L2 serves as the inverting output terminal, and the same-named terminal of the second inductor L2 and the first inductor L1 is grounded; one end of the third inductor L3 is connected to the other end of the first inductor L1 and one end of the fourth inductor L4, and the other end of the third inductor L3 serves as the non-inverting output terminal; the other end of the fourth inductor L4 is grounded.

[0041] At this time, the unbalanced terminal (P1) has a low impedance, and the balanced terminals (P2 and P3) have a high impedance. Among them, L1 < L2. If L1 / L2 = 1:4 in the inverter transformer; L3 = L4 in the autotransformer, and K1 = K2 = 1. The impedance ratio of the unbalanced terminal to the balanced terminal of this balun is 1:4. If L1 = L2 and L1 = 0.2, the balun also becomes a Ruthroff 1:1 balun.

[0042] As shown in FIG. 9, taking the conversion of differential signals to single-ended as an example, at this time, the balanced terminals P2 and P3 are the input terminals, and the unbalanced terminal P1 is the output terminal. It is another structure where the unbalanced terminal (P1) has a low impedance and the balanced terminals (P2 and P3) have a high impedance. Here, L3 = L4. The autotransformer is connected to the unbalanced input terminal. The inverter transformer includes a first inductor L1 and a second inductor L2 which are coupled; the autotransformer includes a third inductor L3 and a fourth inductor L4; the third inductor L3 is connected to the fourth inductor L4 and serves as the input port P1 of the unbalanced terminal. The other end of the fourth inductor L4 is grounded. The other end of the third inductor L3 is connected to one end of the first inductor L1. The other end of the first inductor L1 serves as the non-inverting output terminal. The first inductor L1 is coupled with the second inductor L2. The same-named terminal of the second inductor L2 and the first inductor L1 is grounded. The other end of the second inductor L2 serves as the inverting terminal.

[0043] As shown in FIG. 10, it further includes connecting a fifth inductor L5 at the non-inverting output terminal. One end of the fifth inductor L5 is connected to the non-inverting output terminal, and the other end is grounded. Adding the L5 inductor can improve the amplitude and phase balance performance to further expand the bandwidth of the balun.

[0044] Further preferably, magnetic core materials are embedded in the inductance centers of the inverter transformer and the autotransformer. The inductors of the inverter transformer and the autotransformer are planar single-layer or multi-layer inductance structures in integrated circuit processes or LTCC processes.

[0045] The present invention also provides an application of a novel broadband balun structure for a push-pull amplifier, a high IIP2 amplifier, or a high linearity amplifier; the application comprises two of the novel broadband balun structures described above, wherein the in-phase output end and the inverting output end of one of the impedance transformation balun structures are respectively connected to an amplifier, and the output ends of the two amplifiers are connected to another impedance transformation balun structure.

[0046] The present invention also provides an application of a novel broadband balun structure for a broadband high-linearity mixer, comprising two of the above-mentioned novel broadband balun structures, wherein the in-phase output and the inverting output of one of the impedance transformation balun structures are connected to the mixer, and the output of the mixer is connected to another impedance transformation balun structure.

[0047] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0048] Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are illustrative and are not to be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments without departing from the principles and intent of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A novel broadband balun structure, characterized in that: It includes an inverting transformer and an autotransformer; the inverting transformer is used to invert the input signal to generate an inverted signal; the autotransformer is used to divide the input signal to generate a common-phase signal; one end of the inverting transformer and / or the autotransformer is connected to the signal at the unbalanced end; when one end of the inverting transformer or the autotransformer is connected to the input signal at the unbalanced end, the inverting transformer is connected to the autotransformer; The other end of the inverting transformer serves as an inverting signal end of the balanced end, and the other end of the autotransformer serves as a non-phase signal end of the balanced end.

2. The novel broadband balun structure according to claim 1 is characterized in that: The inverter transformer includes a first inductor L1 and a second inductor L2 coupled to each other; the autotransformer includes a third inductor L3 and a fourth inductor L4; wherein the first inductor L1 and the second inductor L2 are coupled to each other through a magnetic field; the third inductor L3 and the fourth inductor L4 are coupled through a magnetic field, the first inductor L1 and the second inductor L2 are connected in a manner of an inverter transformer, the third inductor L3 and the fourth inductor L4 are connected in a manner of an autotransformer, and one end of the autotransformer is connected to one end of the inverter transformer.

3. The novel broadband balun structure according to claim 1 is characterized in that: The inverting transformer includes a first inductor L1 and a second inductor L2 coupled to each other; the autotransformer includes a third inductor L3 and a fourth inductor L4; one end of the first inductor L1 of the inverting transformer is connected to the unbalanced end, and the other end is connected to the third inductor L3; the second inductor L2 and the opposite-name end of the first inductor L1 are connected to the inverting port of the balanced end, and are grounded with the same-name end of the first inductor L1; the other end of the third inductor L3 is connected to the same-name port of the balanced end, the other end of the third inductor L3 is connected to one end of the fourth inductor L4, and the other end of the fourth inductor L4 is grounded.

4. The novel broadband balun structure according to claim 1 is characterized in that: The inverting transformer includes a first inductor L1 and a second inductor L2 coupled to each other; the autotransformer includes a third inductor L3 and a fourth inductor L4; one end of the first inductor L1 is connected to an unbalanced end, the second inductor L2 and the opposite-name end of the first inductor L1 are connected to an inverting port of a balanced end, and the second inductor L2 and the same-name end of the first inductor L1 are grounded; one end of the third inductor L3 is connected to the other end of the first inductor L1 and one end of the fourth inductor L4, and the other end of the third inductor L3 is connected to the same-name port of the balanced end; the other end of the fourth inductor L4 is grounded.

5. The novel broadband balun structure according to claim 1 is characterized in that: The inverting transformer includes a first inductor L1 and a second inductor L2 coupled to each other; the autotransformer includes a third inductor L3 and a fourth inductor L4; the third inductor L3 is connected to the fourth inductor L4 and serves as a port of an unbalanced end, the other end of the fourth inductor L4 is grounded, the other end of the third inductor L3 is connected to one end of the first inductor L1, the other end of the first inductor L1 is connected to the in-phase port of a balanced end, the first inductor L1 is coupled to the second inductor L2, the second inductor L2 and the in-phase end of the first inductor L1 are grounded, and the other end of the second inductor L2 is connected to the inverting port of the balanced end.

6. The novel broadband balun structure according to claim 4 is characterized in that: The method further includes connecting a fifth inductor L5 to the in-phase port of the balanced end, wherein one end of the fifth inductor L5 is connected to the in-phase port, and the other end is grounded.

7. The novel broadband balun structure according to any one of claims 1 to 5, characterized in that: The inductance center of the inverter transformer and the autotransformer is embedded in the magnetic core material.

8. The novel broadband balun structure according to any one of claims 1 to 5, characterized in that: The inductors of the inverter transformer and the autotransformer are planar single-layer or multi-layer inductor structures in an integrated circuit process or a LTCC process.

9. The novel broadband balun structure according to claims 1-3, characterized in that: The unbalanced end is high impedance and the balanced end is low impedance. In the inverter transformer, the impedance ratio of the first inductor L1 and the second inductor L2 is L1 / L2=n:1, where n can be an integer or a fraction. The ratio of the inductance L3 of the autotransformer to the total inductance formed by L3 and L4 is 1:n. The impedance ratio of the unbalanced end to the balanced end of the balun is n:

1.

10. The novel broadband balun structure according to claims 1, 2, 4 and 5 is characterized in that: The unbalanced end is low resistance, the balanced end is high resistance, the impedance ratio of the first inductor L1 and the second inductor L2 is L1 / L2=1:n, the ratio of the inductance L3 of the autotransformer to the total inductance formed by L3 and L4 is 1:n, and the impedance ratio of the unbalanced end to the balanced end of the balun is 1:n.

11. Application of a novel broadband balun structure, characterized in that: Used for a push-pull amplifier, a high IIP2 amplifier or a high linearity amplifier; comprising two novel broadband balun structures as described in any one of claims 1 to 9 above, wherein the in-phase output terminal and the inverting output terminal of one of the impedance transformation balun structures are respectively connected to an amplifier, and the output terminals of the two amplifiers are connected to another impedance transformation balun structure.

12. Application of a novel broadband balun structure, characterized in that: A broadband high linearity mixer comprises two novel broadband balun structures as described in any one of claims 1 to 9, wherein the in-phase output terminal and the inverting output terminal of one of the impedance transformation balun structures are connected to the mixer, and the output terminal of the mixer is connected to another impedance transformation balun structure.

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