Load transformer and differential amplifier

Abstract

The invention relates to the technical field of wireless communication, and provides a load transformer and a differential amplifier, the load transformer comprises a first metal layer, a second metal layer, a third metal layer and a fourth metal layer which are sequentially stacked, and the first metal layer, the second metal layer, the third metal layer and the fourth metal layer are mutually spaced 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 grounding layer; the load transformer further comprises a first substrate dielectric layer, a second substrate dielectric layer and a third substrate dielectric layer. The first substrate dielectric layer is arranged between the first metal layer and the second metal layer; the second substrate dielectric layer is arranged between the second metal layer and the third metal layer; the third substrate dielectric layer is arranged between the third metal layer and the fourth metal layer. The load transformer is small in area, low in cost and convenient to improve the utilization rate of the substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a load transformer and a differential amplifier. Background Art

[0002] In communication technology, amplifiers are widely used to amplify and enhance signals. In many applications, such as wireless communication, optical communication, radar, and audio amplification, the performance of the amplifier is critical to the overall performance of the system. In the design of differential amplifiers, it is often necessary to achieve mutual conversion from balanced signals (differential signals) to unbalanced signals (single-ended signals). At the same time, it is also necessary to introduce an impedance change network at the output of the differential amplifier to achieve the transformation of the load resistance to the optimal impedance required at the output of the differential amplifier. At this time, the load transformer came into being as a core component.

[0003] Load transformers are used to convert balanced signals (differential signals, i.e. two signals with equal amplitudes and 180° phase difference) into unbalanced signals (single-ended signals or reverse conversion). They are widely used in various occasions, such as interface conversion between differential and single-ended signals, impedance matching, and improving the anti-interference ability of circuits. Fig.12 In the transformer structure shown, Port 1 is an unbalanced port. After a single-ended signal is input, two balanced signals with the same amplitude and a phase difference of 180° can be generated at Port 2 and Port 3 of the transformer. Conversely, when balanced signals with the same amplitude and a phase difference of 180° are input at Port 2 and Port 3 of the transformer, an unbalanced signal will be generated at Port 1 of the transformer. At this time, impedance transformation, second harmonic suppression, and common mode signal suppression can be achieved.

[0004] However, commonly used coplanar coaxial and coplanar spiral transformers will increase the area of ​​the coupling coil to obtain a high Q value (quality factor) and a high K value (magnetic coupling coefficient), which is more expensive. Summary of the invention

[0005] In view of the above deficiencies in the prior art, the present invention proposes a load transformer to solve the problem of high cost of the existing load transformer.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: In a first aspect, an embodiment of the present invention provides a load transformer, comprising a first metal layer, a second metal layer, a third metal layer and a fourth metal layer stacked in sequence, wherein 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 are 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 also includes a first substrate dielectric layer, a second substrate dielectric layer and a third substrate dielectric layer; the first substrate dielectric layer is arranged between the first metal layer and the second metal layer; the second substrate dielectric layer is arranged between the second metal layer and the third metal layer; the third substrate dielectric layer is arranged between the third metal layer and the fourth metal layer.

[0007] Preferably, the thickness of the dielectric layer of the first substrate is 20-25 um, and its dielectric constant is 4.4; The thickness of the second substrate dielectric layer is 20-25 um, and its dielectric constant is 4.4; The thickness of the third substrate dielectric layer is 90-105 um, and its dielectric constant is 4.4.

[0008] Preferably, the first coil layer includes a first annular coil body, a first connecting portion formed by extending one end of the first coil body toward the inner side thereof, and a second connecting portion formed by extending the other end of the first coil body toward the outer side thereof, and the first connecting portion is provided with a first via hole penetrating therethrough; The second coil layer comprises a second coil body in an annular shape, a third connection portion and a fourth connection portion formed by two ends of the second coil body extending outward in the same direction, and a power supply portion formed by a side of the second coil body extending outward away from the third connection portion; the power supply portion is used to connect to an external power source, the second coil body is provided with a second via hole penetrating therethrough, and the first via hole is electrically connected to the second via hole and the third coil layer through a first wire; The third coil layer includes a ring-shaped third coil body and a third via hole formed by the third coil body; the second wire passes through the third via hole to electrically connect the third coil layer and electrically connect the third coil layer with the fourth metal layer.

[0009] Preferably, the first via hole and the second via hole are arranged opposite to each other.

[0010] Preferably, the first coil layer is electrically connected to the third coil layer, the first coil layer is coupled to the second coil layer, and an unbalanced signal generated by the coupling between the first coil layer and the second coil layer 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 , satisfying the following relationship: ; in, 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. Satisfy the following relationship: ; Wherein, w0 is the resonance circuit generated by the inductance and parasitic capacitance between the first coil layer and the second coil layer, 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. Satisfy the following relationship: ; in, L2 is the inductance of the first coil layer, R 2 is the parasitic resistance of the first coil layer.

[0011] Preferably, the first coil layer, the second coil layer and the third coil layer are octagonal coils respectively.

[0012] Preferably, the first coil layer, the second coil layer and the third coil layer are circular structure coils respectively.

[0013] In a second aspect, an embodiment of the present invention provides a differential amplifier, comprising the load transformer as described above.

[0014] Compared with the related art, in the embodiment of the present invention, 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; the first substrate dielectric layer of the load transformer is arranged between the first metal layer and the second metal layer; the second substrate dielectric layer is arranged between the second metal layer and the third metal layer; the third substrate dielectric layer is arranged between the third metal layer and the fourth metal layer; such a stacked transformer can obtain high Q value and high K value while greatly reducing the transformer area by reasonably adopting substrate dielectric layers of 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

[0015] The present invention will be described in detail below in conjunction with the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made in conjunction with the following drawings. In the accompanying drawings: Figure 1 A module diagram of a load transformer provided by an embodiment of the present invention; Figure 2 A partially exploded schematic diagram of a load transformer provided by an embodiment of the present invention; Figure 3 A top view of a polygonal coil of a load transformer provided by an embodiment of the present invention; Figure 4 A top view of a circular coil of a load transformer provided in an embodiment of the present invention; Figure 5 for Figure 4 Schematic diagram of the inductance of the first coil layer; Figure 6 for Figure 4 A schematic diagram of the quality factor of the first coil layer; Figure 7 for Figure 4 Schematic diagram of the inductance of the second coil layer; Figure 8 for Figure 4 A schematic diagram of the quality factor of the second coil layer; Fig. 9 for Figure 4 Schematic diagram of the magnetic coupling coefficient of the load transformer; Fig.10 It is a schematic diagram of the existing coplanar coaxial form; Fig.11 is a schematic diagram of an existing coplanar spiral form; Fig.12 It is a structural schematic diagram of an existing load transformer.

[0016] Among them, 100, load transformer, 1, first metal layer, 11, first coil layer, 111, first coil body, 112, first connection part, 113, second connection part, 2, second metal layer, 21, second coil layer, 211, second coil body, 212, third connection part, 213, fourth connection part, 214, power supply part, 3, third metal layer, 31, third coil layer, 32, third via, 4, fourth metal layer, 5, first substrate dielectric layer, 6, second substrate dielectric layer, 7, third substrate dielectric layer, 8, first via, 9, second via. DETAILED DESCRIPTION

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of the present application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0018] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Embodiment 1 See also Figure 1-Figure 4As shown, an embodiment of the present invention provides a load transformer 100, comprising a first metal layer 1, a second metal layer 2, a third metal layer 3 and a fourth metal layer 4 stacked in sequence, wherein 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 asymmetrically arranged; 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 also 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 arranged between the first metal layer 1 and the second metal layer 2; the second substrate dielectric layer 6 is arranged between the second metal layer 2 and the third metal layer 3; the third substrate dielectric layer 7 is arranged between the third metal layer 3 and the fourth metal layer 4. The first metal layer 1, the second metal layer 2, the third metal layer 3 and the fourth metal layer 4 are arranged asymmetrically and spaced from each other; 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 arranged between the first metal layer 1 and the second metal layer 2; the second substrate dielectric layer 6 is arranged between the second metal layer 2 and the third metal layer 3; the third substrate dielectric layer 7 is arranged between the third metal layer 3 and the fourth metal layer 4; such a stacked transformer can obtain high Q value and high K value while greatly reducing the transformer area by reasonably adopting substrate dielectric layers of different thicknesses. The area of ​​the substrate occupied by the transformer is effectively saved, and the substrate utilization rate is improved.

[0021] In this embodiment, the thickness of the first substrate dielectric layer 5 is 20-25 um, and its dielectric constant is 4.4; the thickness of the second substrate dielectric layer 6 is 20-25 um, and its dielectric constant is 4.4; the thickness of the third substrate dielectric layer 7 is 90-105 um, and its dielectric constant is 4.4.

[0022] 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 of different thicknesses, high Q values ​​and high K values ​​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 utilization rate of the substrate.

[0023] In this embodiment, the first coil layer 11 includes a first coil body 111 in an annular shape, a first connection portion 112 formed by extending one end of the first coil body 111 toward the inner side thereof, and a second connection portion 113 formed by extending the other end of the first coil body 111 toward the outer side thereof, and the first connection portion 112 is provided with a first via hole 8 penetrating therethrough. The first coil body 111 is used to realize structural support, the first connection portion 112 is used to be electrically connected to the second coil layer 21, and the second connection portion 113 is used to output an unbalanced signal.

[0024] The second coil layer 21 includes a second coil body 211 in an annular shape, a third connection portion 212 and a fourth connection portion 213 formed by two ends of the second coil body 211 extending outward in the same direction, and a power supply portion 214 formed by a side of the second coil body 211 extending outward away from the third connection portion 212; the power supply portion 214 is used to connect an external power source, the second coil body 211 is provided with a second via hole 9 penetrating therethrough, and the first via hole 8 is electrically connected to the second via hole 9 and the third coil layer 31 through a first wire. The third coil layer 31 includes a third coil body in an annular shape and a third via hole 32 penetrating the third coil body; the second wire passes through the third via hole 32 to electrically connect and electrically connect the third coil layer 31 with the fourth metal layer 4. After the third connection part 212 and the fourth connection part 213 are used to input balanced signals with the same amplitude respectively, they are electrically connected to the second via hole 8 and the second via hole 9, so that the second coil layer 21 and the first coil layer 11 form a transformer coupling, and then an unbalanced signal is generated through the second connection part 113 of the first coil layer 11. At this time, impedance transformation, second harmonic suppression, and common mode signal suppression can be achieved.

[0025] In this embodiment, the first via hole 8 and the second via hole 9 are arranged opposite to each other along the axial direction, so as to facilitate the electrical connection between the first coil layer 11 and the second coil layer 21 .

[0026] In this embodiment, the first coil layer 11 is electrically connected to the third coil layer 31 , the first coil layer 11 is coupled to the second coil layer 21 , and an unbalanced signal generated by the coupling between the first coil layer 111 and the second coil layer 21 is output through the second connection portion 113 .

[0027] Among them, the magnetic coupling coefficient between the first coil layer 11 and the second coil layer 21 is k , satisfying 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 of the second coil layer 21. Magnetic coupling coefficient kIt is related to the plate stacking, the coupling area of ​​the first coil layer 11 and the second coil layer 21, etc.

[0028] The quality factor of the first coil layer 11 is Q 1. Satisfy the following relationship: Wherein, w0 is the resonance circuit generated by the inductance and parasitic capacitance between the first coil layer 11 and the second coil layer 21, L1 is the inductance of the first coil layer 11, R1 is the parasitic resistance of the first coil layer 11. The quality factor is related to the plate stacking, shape and area of ​​the first coil layer 11.

[0029] The quality factor of the second coil layer 21 is Q 2. Satisfy the following relationship: ; in, L2 is the inductance of the first coil layer 11, R 2 is the parasitic resistance of the first coil layer 11 .

[0030] Specifically, taking a circular load transformer 100 as an example, the area of ​​the 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 are respectively input with balanced signals (differential signals), the power supply part 214 is used to ground the RF equivalent, connects the third coil layer 31 through the first coil layer 11, and couples with the second coil layer 21 to generate an unbalanced signal output at the port of the second connection part 113. k The higher the Q, the smaller the insertion loss of the transformer and the better the performance of the power amplifier output.

[0031] In this embodiment, the first coil layer 11 , the second coil layer 21 , and the third coil layer 31 are octagonal coils respectively.

[0032] In this embodiment, the first coil layer 11 , the second coil layer 21 and the third coil layer 31 are circular structure coils respectively.

[0033] In this embodiment, Figure 5-Figure 9 for Figure 4 The simulation parameters of the circular coil load transformer 100 are as follows: the inductance L1 is the inductance of the circular coil connecting the first metal layer 1 to the third metal layer 3, and 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 portion 212 and the fourth connection portion 213 are located, and Q2 is the quality factor of the inductance L2. L1=2nH, Q1=52; L2=0.57nH, Q2=44; the magnetic coupling coefficient k=0.75; Fig.10The k value of the existing coplanar coaxial is between 0.3 and 0.5. Fig.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.

[0034] Embodiment 2 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.

[0035] 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, comprising a first metal layer, a second metal layer, a third metal layer and a fourth metal layer stacked in sequence, wherein 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 are 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 also includes a first substrate dielectric layer, a second substrate dielectric layer and a third substrate dielectric layer; the first substrate dielectric layer is arranged between the first metal layer and the second metal layer; the second substrate dielectric layer is arranged between the second metal layer and the third metal layer; the third substrate dielectric layer is arranged between the third metal layer and the fourth metal layer.

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

4.

3. The load transformer according to claim 1, characterized in that: The first coil layer includes a first annular coil body, a first connecting portion formed by extending one end of the first coil body toward the inner side thereof, and a second connecting portion formed by extending the other end of the first coil body toward the outer side thereof, wherein the first connecting portion is provided with a first via hole penetrating therethrough; The second coil layer comprises a second coil body in an annular shape, a third connection portion and a fourth connection portion formed by two ends of the second coil body extending outward in the same direction, and a power supply portion formed by a side of the second coil body extending outward away from the third connection portion; the power supply portion is used to connect to an external power source, the second coil body is provided with a second via hole penetrating therethrough, and the first via hole is electrically connected to the second via hole and the third coil layer through a first wire; The third coil layer includes a ring-shaped third coil body and a third via hole formed by the third coil body; the second wire passes through the third via hole to electrically connect the third coil layer and electrically connect the third coil layer with the fourth metal layer.

4. The load transformer according to claim 3, characterized in that: The first via hole and the second via hole are arranged opposite to each other along the axial direction.

5. The load transformer according to claim 3, characterized in that: The first coil layer is electrically connected to the third coil layer, the first coil layer is coupled to the second coil layer, and an unbalanced signal generated by the coupling between the first coil layer and the second coil layer 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 , satisfying the following relationship: ; in, 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. Satisfy the following relationship: ; Wherein, w0 is the resonance circuit generated by the inductance and parasitic capacitance between the first coil layer and the second coil layer, 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. Satisfy the following relationship: ; in, L2 is the inductance of the first coil layer, R 2 is the parasitic resistance of the first coil layer.

6. The load transformer according to claim 1, characterized in that: The first coil layer, the second coil layer, and the third coil layer are octagonal coils respectively.

7. The load transformer according to claim 1, characterized in that: The first coil layer, the second coil layer and the third coil layer are circular structure coils respectively.

8. A differential amplifier, characterized in that: Comprising a load transformer as described in any one of claims 1-7.

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