Load transformer and differential amplifier

Abstract

The present invention relates to the field of wireless communication technologies, and provides a load transformer and a differential amplifier, which include a first metal layer, a second metal layer, a third metal layer, and a fourth metal layer that are sequentially stacked. The first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are spaced apart from each other and asymmetrically arranged; the first metal layer is an annular first coil layer, the second metal layer is an annular second coil layer, the third metal layer is an annular third coil layer, and the fourth metal layer is a ground layer; the load transformer further includes a first substrate dielectric layer, a second substrate dielectric layer, and a third substrate dielectric layer; the first substrate dielectric layer is disposed between the first metal layer and the second metal layer; the second substrate dielectric layer is disposed between the second metal layer and the third metal layer; the third substrate dielectric layer is disposed between the third metal layer and the fourth metal layer. The load transformer of the present invention has a small area, low cost, and is convenient for improving the substrate utilization rate.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and particularly to a load transformer and a differential amplifier. Background Art

[0002] In communication technologies, amplifiers are widely used for signal amplification and enhancement. In many applications, such as wireless communication, optical communication, radar, and audio amplification, the performance of the amplifier is crucial to the overall performance of the system. In the design of differential amplifiers, it is often necessary to achieve the mutual conversion between balanced signals (differential signals) and unbalanced signals (single-ended signals), and at the same time, an impedance change network needs to be introduced at the output end of the differential amplifier to realize the transformation from the load resistance to the optimal impedance required at the output end of the differential amplifier. At this time, the load transformer emerges as the core device.

[0003] A load transformer is used to convert balanced signals (differential signals, that is, two signals with equal amplitudes and a phase difference of 180°) into unbalanced signals (single-ended signals) or perform reverse conversion, and is widely used in various occasions, such as the interface conversion between differential and single-ended signals, impedance matching, improving the anti-interference ability of the circuit, etc. As Figure 12 shown in the transformer structure, the Port1 is an unbalanced port. After inputting a single-ended signal, two balanced signals with the same amplitude and a phase difference of 180° can be generated at the Port2 and Port3 of the transformer respectively. Conversely, when balanced signals with the same amplitude and a phase difference of 180° are input at the Port2 and Port3 of the transformer respectively, an unbalanced signal will be generated at the Port1 of the transformer. At this time, impedance transformation, second harmonic suppression, and common mode signal suppression can be achieved.

[0004] However, for commonly used transformers in the form of coplanar coaxial and coplanar spiral, the area of the coupling coil is made large to obtain a high Q value (quality factor) and a high K value (magnetic coupling coefficient), resulting in a high cost. Summary of the Invention

[0005] Aiming at the above deficiencies of the prior art, the present invention proposes a load transformer to solve the problem of the high cost of existing load transformers.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a load transformer, which includes a first metal layer, a second metal layer, a third metal layer, and a fourth metal layer stacked in sequence. The first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are electrically connected to each other. The first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are spaced apart from each other and arranged asymmetrically. The first metal layer is a ring-shaped first coil layer, the second metal layer is a ring-shaped second coil layer, the third metal layer is a ring-shaped third coil layer, and the fourth metal layer is a grounding layer.

[0008] The load transformer further includes a first substrate dielectric layer, a second substrate dielectric layer, and a third substrate dielectric layer. The first substrate dielectric layer is disposed between the first metal layer and the second metal layer. The second substrate dielectric layer is disposed between the second metal layer and the third metal layer. The third substrate dielectric layer is disposed between the third metal layer and the fourth metal layer.

[0009] Preferably, the thickness of the first substrate dielectric layer is 20 - 25 um, and its dielectric constant is 4.4.

[0010] The thickness of the second substrate dielectric layer is 20 - 25 um, and its dielectric constant is 4.4.

[0011] The thickness of the third substrate dielectric layer is 90 - 105 um, and its dielectric constant is 4.4.

[0012] Preferably, the first coil layer includes a ring-shaped first coil body, a first connection portion extending from one end of the first coil body toward its inner side, and a second connection portion extending from the other end of the first coil body toward its outer side. The first connection portion is provided with a first through hole penetrating therethrough.

[0013] The second coil layer includes a ring-shaped second coil body, a third connection portion and a fourth connection portion extending from both ends of the second coil body toward its outer side in the same direction, and a power supply portion extending outward from a side of the second coil body away from the third connection portion. The power supply portion is used to connect to an external power supply. The second coil body is provided with a second through hole penetrating therethrough. The first through hole, the second through hole, and the third coil layer are electrically connected by a first wire.

[0014] The third coil layer includes a ring-shaped third coil body and a third through hole formed by penetrating the third coil body. A second wire passes through the third through hole for electrical connection to electrically connect the third coil layer and the fourth metal layer.

[0015] Preferably, the first through hole and the second through hole are disposed opposite to each other.

[0016] Preferably, the first coil layer is electrically connected to the third coil layer, the first coil layer is coupled with the second coil layer, and the unbalanced signal generated by the coupling of the two is output through the second connection part;

[0017] Wherein, the magnetic coupling coefficient between the first coil layer and the second coil layer is k , satisfying the following relationship: ;

[0018] Wherein, M represents the mutual inductance coefficient, L 1 represents the self-inductance coefficient of the first coil layer, L 2 represents the self-inductance coefficient of the second coil layer;

[0019] The quality factor of the first coil layer is Q 1, satisfying the following relationship: ;

[0020] Wherein, w0 is the resonance of the inductance and parasitic capacitance between the first coil layer and the second coil layer to generate a resonance circuit, L1 is the inductance of the first coil layer, R1 is the parasitic resistance of the first coil layer;

[0021] The quality factor of the second coil layer is Q 2, satisfying the following relationship: ;

[0022] Wherein, L2 is the inductance of the first coil layer, R 2 is the parasitic resistance of the first coil layer.

[0023] Preferably, the first coil layer, the second coil layer and the third coil layer are octagonal coils respectively.

[0024] Preferably, the first coil layer, the second coil layer and the third coil layer are circular structure coils respectively.

[0025] In a second aspect, an embodiment of the present invention provides a differential amplifier, including the load transformer as described above.

[0026] In the embodiments of the present invention, compared with the related art, the first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are spaced apart from each other and asymmetrically arranged; the first metal layer is a circular first coil layer, the second metal layer is a circular second coil layer, the third metal layer is a circular third coil layer, and the fourth metal layer is a grounding layer; the first substrate dielectric layer of the load transformer is disposed between the first metal layer and the second metal layer; the second substrate dielectric layer is disposed between the second metal layer and the third metal layer; the third substrate dielectric layer is disposed between the third metal layer and the fourth metal layer; the transformer in such a stacked form can obtain a high Q value and a high K value while significantly reducing the area of the transformer by reasonably adopting substrate dielectric layers with different thicknesses. It effectively saves the area of the substrate occupied by the transformer and improves the substrate utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be described in detail below with reference to the drawings. Through the detailed description in combination with the following drawings, the above or other aspects of the present invention will become clearer and easier to understand. In the drawings:

[0028] Figure 1 is a module diagram of a load transformer provided by an embodiment of the present invention;

[0029] Figure 2 is a partial exploded view of a load transformer provided by an embodiment of the present invention;

[0030] Figure 3 is a top view of a polygonal coil of a load transformer provided by an embodiment of the present invention;

[0031] Figure 4 is a top view of a circular coil of a load transformer provided by an embodiment of the present invention;

[0032] Figure 5 is Figure 4 a schematic diagram of the inductance of the first coil layer of;

[0033] Figure 6 is Figure 4 a schematic diagram of the quality factor of the first coil layer of;

[0034] Figure 7 is Figure 4 a schematic diagram of the inductance of the second coil layer of;

[0035] Figure 8 is Figure 4 a schematic diagram of the quality factor of the second coil layer of;

[0036] Figure 9 is Figure 4 a schematic diagram of the magnetic coupling coefficient of the load transformer of;

[0037] Figure 10Schematic diagram of an existing coplanar coaxial form;

[0038] Figure 11 Schematic diagram of an existing coplanar spiral form;

[0039] Figure 12 Schematic diagram of the structure of an existing load transformer.

[0040] Among them, 100 is the load transformer, 1 is the first metal layer, 11 is the first coil layer, 111 is the first coil body, 112 is the first connection part, 113 is the second connection part, 2 is the second metal layer, 21 is the second coil layer, 211 is the second coil body, 212 is the third connection part, 213 is the fourth connection part, 214 is the power supply part, 3 is the third metal layer, 31 is the third coil layer, 32 is the third via, 4 is the fourth metal layer, 5 is the first substrate dielectric layer, 6 is the second substrate dielectric layer, 7 is the third substrate dielectric layer, 8 is the first via, and 9 is the second via. Detailed implementation manners

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used in the description of this application in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of this application or the above drawings are used to distinguish different objects and not to describe a specific order.

[0042] Referring to "embodiment" herein means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of this application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0044] Embodiment 1

[0045] Please refer to Figures 1-4As shown in the figure, an embodiment of the present invention provides a load transformer 100, which includes a first metal layer 1, a second metal layer 2, a third metal layer 3, and a fourth metal layer 4 stacked in sequence. The first metal layer 1, the second metal layer 2, the third metal layer 3, and the fourth metal layer 4 are electrically connected to each other; the first metal layer 1, the second metal layer 2, the third metal layer 3, and the fourth metal layer 4 are spaced apart from each other and arranged asymmetrically; the first metal layer 1 is a ring-shaped first coil layer 11, the second metal layer 2 is a ring-shaped second coil layer 21, the third metal layer 3 is a ring-shaped third coil layer 31, and the fourth metal layer 4 is a grounding layer. The load transformer 100 further includes a first substrate dielectric layer 5, a second substrate dielectric layer 6, and a third substrate dielectric layer 7; the first substrate dielectric layer 5 is disposed between the first metal layer 1 and the second metal layer 2; the second substrate dielectric layer 6 is disposed between the second metal layer 2 and the third metal layer 3; the third substrate dielectric layer 7 is disposed between the third metal layer 3 and the fourth metal layer 4. By arranging the first metal layer 1, the second metal layer 2, the third metal layer 3, and the fourth metal layer 4 to be spaced apart from each other and arranged asymmetrically; the first metal layer 1 is a ring-shaped first coil layer 11, the second metal layer 2 is a ring-shaped second coil layer 21, the third metal layer 3 is a ring-shaped third coil layer 31, and the fourth metal layer 4 is a grounding layer; the first substrate dielectric layer 5 of the load transformer 100 is disposed between the first metal layer 1 and the second metal layer 2; the second substrate dielectric layer 6 is disposed between the second metal layer 2 and the third metal layer 3; the third substrate dielectric layer 7 is disposed between the third metal layer 3 and the fourth metal layer 4; a transformer in such a stacked form can obtain high Q value and high K value while greatly reducing the area of the transformer by reasonably using substrate dielectric layers with different thicknesses. It effectively saves the area of the substrate occupied by the transformer and improves the substrate utilization rate.

[0046] In this embodiment, the thickness of the first substrate dielectric layer 5 is 20 - 25um, and its dielectric constant is 4.4; the thickness of the second substrate dielectric layer 6 is 20 - 25um, and its dielectric constant is 4.4; the thickness of the third substrate dielectric layer 7 is 90 - 105um, and its dielectric constant is 4.4.

[0047] Specifically, the thickness of the first substrate dielectric layer 5 is 25um, and its dielectric constant is 4.4; the thickness of the second substrate dielectric layer 6 is 25um, and its dielectric constant is 4.4; the thickness of the third substrate dielectric layer 7 is 105um, and its dielectric constant is 4.4. In this way, by reasonably using substrate dielectric layers with different thicknesses, high Q value and high K value can be obtained while greatly reducing the area of the transformer; thereby effectively saving the area of the substrate occupied by the transformer and improving the substrate utilization rate.

[0048] In this embodiment, the first coil layer 11 includes a ring-shaped first coil body 111, a first connection portion 112 extending from one end of the first coil body 111 towards its inner side, and a second connection portion 113 extending from the other end of the first coil body 111 towards its outer side. A first through hole 8 is provided through the first connection portion 112. The first coil body 111 is used to achieve structural support, the first connection portion 112 is used for electrical connection with the second coil layer 21, and the second connection portion 113 is used to output an unbalanced signal.

[0049] The second coil layer 21 includes a ring-shaped second coil body 211, a third connection portion 212 and a fourth connection portion 213 extending from both ends of the second coil body 211 towards the same outer side, and a power supply portion 214 extending outward from a side of the second coil body 211 away from the third connection portion 212. The power supply portion 214 is used to connect to an external power supply. A second through hole 9 is provided through the second coil body 211. The first through hole 8, the second through hole 9, and the third coil layer 31 are electrically connected by a first wire. The third coil layer 31 includes a ring-shaped third coil body and a third through hole 32 formed through the third coil body. A second wire passes through the third through hole 32 for electrical connection to electrically connect the third coil layer 31 and the fourth metal layer 4. After the same-amplitude balanced signals are respectively input through the third connection portion 212 and the fourth connection portion 213, and are electrically connected through the first through hole 8 and the second through hole 9, the second coil layer 21 and the first coil layer 11 form a transformer coupling. Then, an unbalanced signal is generated through the second connection portion 113 of the first coil layer 11. At this time, impedance transformation, second harmonic suppression, and common-mode signal suppression can be achieved.

[0050] In this embodiment, the first through hole 8 and the second through hole 9 are axially aligned. This facilitates the electrical connection between the first coil layer 11 and the second coil layer 21.

[0051] In this embodiment, the first coil layer 11 is electrically connected to the third coil layer 31. The first coil layer 11 is coupled with the second coil layer 21, and the unbalanced signal generated by the coupling of the two is output through the second connection portion 113.

[0052] Among them, the magnetic coupling coefficient between the first coil layer 11 and the second coil layer 21 is k , and satisfies the following relationship: ; M represents the mutual inductance coefficient, L 1 represents the self-inductance coefficient of the first coil layer 11, L 2 represents the self-inductance coefficient of the second coil layer 21. The magnetic coupling coefficient kIt is related to the lamination of plates, the coupling area between the first coil layer 11 and the second coil layer 21, etc.

[0053] The quality factor of the first coil layer 11 is Q 1, satisfying the following relationship: ; where w0 is the resonance of the inductance and parasitic capacitance between the first coil layer 11 and the second coil layer 21 to generate a resonant circuit, L1 is the inductance of the first coil layer 11, R1 is the parasitic resistance of the first coil layer 11. This quality factor is related to the lamination of plates, shape, area, etc. of the first coil layer 11.

[0054] The quality factor of the second coil layer 21 is Q 2, satisfying the following relationship: ;

[0055] Among them, L2 is the inductance of the first coil layer 11, R 2 is the parasitic resistance of the first coil layer 11.

[0056] Specifically, taking the circular load transformer 100 as an example, the area of this load transformer 100 is 1.16 mm 2 . When the third connection part 212 and the fourth connection part 213 of the second coil layer 21 respectively input balanced signals (differential signals), the power supply part 214 is used to be equivalent to ground for radio frequency, and through the first coil layer 11 to connect the third coil layer 31, the unbalanced signal generated by coupling with the second coil layer 21 is output at the port of the second connection part 113. When k is higher and Q is higher, the insertion loss generated by the transformer is smaller, and the performance of the power amplifier output is better.

[0057] In this embodiment, the first coil layer 11, the second coil layer 21, and the third coil layer 31 are respectively octagonal coils.

[0058] In this embodiment, the first coil layer 11, the second coil layer 21, and the third coil layer 31 are respectively circular structure coils.

[0059] In this embodiment, Figures 5-9 is Figure 4 the simulation parameters of the circular coil load transformer 100, the inductance L1 is the inductance of the circular coil connecting the first metal layer 1 and the third metal layer 3, Q1 is the quality factor of the inductance L1; the inductance L2 is the inductance of the circular coil of the second metal layer 2 where the third connection part 212 and the fourth connection part 213 are located, Q2 is the quality factor of the inductance L2. L1 = 2 nH, Q1 = 52; L2 = 0.57 nH, Q2 = 44; the magnetic coupling coefficient k = 0.75; Figure 10The k value of the existing coplanar coaxial is between 0.3 and 0.5. Figure 11 The k value of the existing coplanar spiral transformer is between 0.5 and 0.7. The k value of the stacked circular load transformer 100 of the present invention is higher than 0.7, which can reduce the insertion loss of the transformer and improve the output performance of the differential amplifier.

[0060] Embodiment 2

[0061] The embodiment of the present invention provides a differential amplifier, including the load transformer 100 as described above. The technical effect produced by the differential amplifier of this embodiment is the same as that of the first embodiment, and will not be described here.

[0062] It should be noted that the various embodiments described above with reference to the accompanying drawings are only used to illustrate the present invention rather than to limit the scope of the present invention. Those skilled in the art should understand that any modification or equivalent substitution of the present invention without departing from the spirit and scope of the present invention should be included within the scope of the present invention. In addition, unless otherwise indicated by the context, words appearing in the singular include the plural form, and vice versa. In addition, unless otherwise specified, all or part of any embodiment may be used in combination with all or part of any other embodiment.

Claims

1. A load transformer includes a first metal layer, a second metal layer, a third metal layer, and a fourth metal layer that are sequentially stacked and arranged, and the first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are electrically connected to each other; characterized in that, The first metal layer, the second metal layer, the third metal layer, and the fourth metal layer are spaced apart from each other and arranged asymmetrically; the first metal layer is a ring-shaped first coil layer, the second metal layer is a ring-shaped second coil layer, the third metal layer is a ring-shaped third coil layer, and the fourth metal layer is a ground layer; The load transformer further includes a first substrate dielectric layer, a second substrate dielectric layer, and a third substrate dielectric layer; the first substrate dielectric layer is disposed between the first metal layer and the second metal layer; the second substrate dielectric layer is disposed between the second metal layer and the third metal layer; the third substrate dielectric layer is disposed between the third metal layer and the fourth metal layer; The first coil layer includes a ring-shaped first coil body, a first connection portion extending from one end of the first coil body toward its inner side, and a second connection portion extending from the other end of the first coil body toward its outer side, and a first via hole is formed through the first connection portion; The second coil layer includes a ring-shaped second coil body, a third connection portion and a fourth connection portion extending from both ends of the second coil body in the same direction toward its outer side, and a power supply portion extending outward from a side of the second coil body away from the third connection portion; the power supply portion is used to connect to an external power supply, a second via hole is formed through the second coil body, and the first via hole, the second via hole, and the third coil layer are electrically connected by a first wire; The third coil layer includes a ring-shaped third coil body and a third via hole formed through the third coil body; a second wire passes through the third via hole for electrical connection to electrically connect the third coil layer and the fourth metal layer.

2. The load transformer according to claim 1, wherein The thickness of the first substrate dielectric layer is 20 - 25 μm, and its dielectric constant is 4.4; The thickness of the second substrate dielectric layer is 20 - 25 μm, and its dielectric constant is 4.4; The thickness of the third substrate dielectric layer is 90 - 105 μm, and its dielectric constant is 4.

4.

3. The load transformer according to claim 1, characterized in that, The first via hole and the second via hole are arranged axially opposite to each other.

4. The load transformer according to claim 1, wherein The first coil layer is electrically connected to the third coil layer, the first coil layer is coupled with the second coil layer, and the unbalanced signal generated by the coupling of the two is output through the second connection portion; Among them, the magnetic coupling coefficient between the first coil layer and the second coil layer is k , and satisfies the following relationship: ; Among them, M represents the mutual inductance coefficient, L 1 represents the self-inductance coefficient of the first coil layer, L 2 represents the self-inductance coefficient of the second coil layer; The quality factor of the first coil layer is Q 1, and satisfies the following relationship: ; wherein, w0 is the resonance of the inductance and parasitic capacitance between the first coil layer and the second coil layer to generate a resonant circuit, L1 is the inductance of the first coil layer, R1 is the parasitic resistance of the first coil layer; The quality factor of the second coil layer is Q 2, and satisfies the following relationship: ; Among them, L2 is the inductance of the first coil layer, R 2 is the parasitic resistance of the first coil layer.

5. The load transformer according to claim 1, wherein, The first coil layer, the second coil layer, and the third coil layer are respectively octagonal coils.

6. The load transformer according to claim 1, wherein, The first coil layer, the second coil layer, and the third coil layer are respectively circular structure coils.

7. A differential amplifier, characterized in that, It includes the load transformer according to any one of claims 1 - 6.

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