JP6589208B2 - Balun transformer and power amplifier using the same - Google Patents

Description

  The present invention relates to a balun transformer, and more particularly to a balun transformer that connects an unbalanced terminal and a balanced terminal by impedance conversion and a power amplifier using the balun transformer.

The balun transformer is a circuit that connects an unbalanced terminal and a balanced terminal by impedance conversion.
Conventionally, in a balun transformer using a quarter-wavelength coupled transmission line, a theoretical design equation based on a coupled line theory has been proposed (see, for example, Patent Document 1).
However, when a quarter-wavelength coupled transmission line is used, there is a problem that the circuit size of the balun transformer becomes too large.
In addition, a theoretical design equation of a balun transformer using a coupled transmission line composed of two transmission lines having an electrical length of 1 [rad] or less without using a quarter wavelength coupled transmission line has been proposed ( For example, refer nonpatent literature 1).
However, when a coupled transmission line is used, the insertion loss may increase when the transmission line is composed of two transmission lines.

JP 2006-121313 A

C-2-55 “2 GHz band ultra-compact CMOS on-chip balun with double-wave demultiplexing function” 2016 IEICE General Conference Proceedings (Electronics Proceedings 1) 84, 2016/3/15 -18

  In a balun transformer using an integrated circuit, a design equation of a balun transformer based on a coupled line theory is coupled with an electrical length of 1 [rad] or less in accordance with a coupled line theory in accordance with a demand for miniaturization of the chip size of the integrated circuit. A transmission line has been established. However, in order to reduce the insertion loss, the number of transmission lines constituting the coupled transmission line may be increased. However, the design equation in that case has not been established.

  In view of the above problems, the present invention proposes a design equation based on a coupled line theory for a balun transformer using a coupled transmission line having an electrical length of 3 [rad] or less composed of three or more transmission lines. An object of the present invention is to provide a balun transformer having a small insertion loss, a small size and good electrical characteristics, and a power amplifier using the balun transformer.

In the balun transformer for converting an unbalanced signal and a balanced signal, the present invention provides an even mode admittance of a periodic structure coupled transmission line in which the admittance of the unbalanced terminal is L _S , the admittance of the balanced terminal is Y _L , and adjacent lines are coupled. When Y ^′ _oe and odd mode admittance Y ^′ _oo , the characteristic admittance of the microstrip line is Y _O , and the electrical length is θ, these are balun transformers configured to satisfy a predetermined design equation.

  ADVANTAGE OF THE INVENTION According to this invention, a small and low-loss balun transformer and a power amplifier using the same can be provided.

It is a circuit structure figure which shows the balun transformer in Embodiment 1 of this invention. FIG. 3 is an equivalent circuit diagram of the balun transformer in the first embodiment of the present invention. It is an equivalent circuit diagram for demonstrating the equivalent circuit of the balun transformer in Embodiment 1 of this invention. It is a circuit diagram which shows the capacity | capacitance model of the cross section of the coupling transmission line of the balun transformer in Embodiment 1 of this invention. It is a circuit diagram which shows the capacity | capacitance model of the cross section of the coupling transmission line of the balun transformer in Embodiment 1 of this invention. It is a circuit diagram which shows the capacity | capacitance model of the cross section of the coupling transmission line of the balun transformer in Embodiment 1 of this invention. It is an equivalent circuit schematic in the coupling | bonding transmission line part of the balun transformer which concerns on Embodiment 1 of this invention. It is the equivalent circuit schematic which simplified and showed the equivalent circuit of the balun transformer in Embodiment 1 of this invention. It is a circuit structure figure which shows the case where the number of the transmission lines in the balun transformer which concerns on Embodiment 1 of this invention is three. It is sectional drawing of the coupling transmission line in the Example of the balun transformer which concerns on Embodiment 1 of this invention. It is a figure which shows the measurement result of the input reflection characteristic in the Example of the balun transformer which concerns on Embodiment 1 of this invention, and an equivalent circuit simulation. It is a figure which shows the measurement result of the passage amplitude characteristic in the Example of the balun transformer which concerns on Embodiment 1 of this invention, and an equivalent circuit simulation. It is a figure which shows the measurement result of the passage phase characteristic in the Example of the balun transformer which concerns on Embodiment 1 of this invention, and an equivalent circuit simulation. It is a circuit structure figure which shows the balun transformer in Embodiment 2 of this invention. It is the equivalent circuit schematic of the balun transformer in Embodiment 2 of this invention. It is a circuit structure figure which shows the balun transformer in Embodiment 3 of this invention. It is the equivalent circuit schematic of the balun transformer in Embodiment 3 of this invention. It is a circuit structure figure which shows the balun transformer in Embodiment 4 of this invention. It is a circuit structure figure which shows the power amplifier in Embodiment 5 using the balun transformer which concerns on this invention. It is a circuit structure figure which shows the power amplifier in Embodiment 6 using the balun transformer which concerns on this invention.

Embodiment 1 FIG.
A balun transformer 1000 according to the first embodiment of the present invention will be described. FIG. 1 is a circuit structure diagram of a balun transformer 1000 according to the first embodiment.
The balun transformer 1000 is an electric circuit that converts an input unbalanced signal into a balanced signal that is 180 degrees out of phase, and is an electric circuit that converts the impedance of the unbalanced terminal and the balanced terminal.
Balun transformer 1000, admittance _Y is _S unbalanced terminal P1, admittance _{Y L} a is balanced terminals P2, P3, (the N odd, N ≧ 3) Nos. 1 through N transmission line 11, 12, & -1N is provided. Transmission lines 11, 12,..., 1N have a line width of W, and these lines are periodically arranged at intervals S (left and right or up and down), and adjacent lines are electromagnetically coupled to each other. A transmission line 111 is configured. The second, fourth,..., N-1 transmission lines, that is, the even-numbered transmission lines 12, 14,. , N, that is, odd-numbered transmission lines 11, 13,..., 1N are connected to each other by terminals 3 and 4. Insertion loss can be reduced by increasing the number N of transmission lines. In addition, optimum impedance conversion can be performed.
Although FIG. 1 shows a balun transformer in which the terminals 3 and 4 are provided at the right side position, the terminals 3 and 4 may be provided at any position according to the application. The terminal 1 is connected to the unbalanced terminal P1, which is the first load, and the terminal 2 is short-circuited to the ground. Terminals 3 and 4 are connected to balanced terminals P2 and P3, which are second and third loads, respectively. A capacitor C ₁ is connected in parallel to the unbalanced terminal P1, and a capacitor C ₂ is connected between the balanced terminals P2 and P3. Note that the capacitor C ₁ and the capacitor C ₂ do not have to be connected, and when not connected, C ₁ = 0 or C ₂ = 0. Transmission lines 11, 12, ..., the line length of 1N (electrical length) is 2θ ≦ 1 [rad] or less with respect to the design frequency _{f 0.} Although the balun transformer 1000 of FIG. 1 is an octagon, the shape of the balun transformer 1000 may be any polygon, a circle, or a straight line.
FIG. 2 is an equivalent circuit diagram of the balun transformer 1000 according to the first embodiment. The coupled transmission line 111 shown in FIG. 1 has coupled transmission lines 51 and 52 whose even mode characteristic admittance is Y ^′ _oe , odd mode characteristic admittance is Y ^′ _oo , the line length is θ, the characteristic admittance is Y _O , and the line length is θ. Transmission lines 31 and 32, and impedance transformers 61 to 68 having an impedance transformation ratio of 1: √ {(N−1) / 2}. Here, Y ^′ _oe and Y ^′ _oo are even-mode characteristic admittance and odd mode of a periodically coupled transmission line that is periodically arranged with a line width W and a line interval S and electromagnetically couples between adjacent lines. It is characteristic admittance. Y _O is the characteristic admittance of a microstrip line having a line width W.
From the equivalent circuit, the input admittance Y _in which expects the balun transformer side from the terminal 1 can be expressed by the following equation (1).

On the other hand, the load admittance Y ^′ _S that expects the unbalanced terminal P1 side from the terminal 1 is selected so as to be complex conjugate matched to Y _in at the design frequency f ₀ . That is, Y ^′ _S can be expressed by the following equation (2).

  Since the circuit element used for the equivalent circuit of FIG. 2 is provided in a general commercially available circuit simulator, the first embodiment of the present invention is characterized in that it can be calculated by the circuit simulator.

[Derivation of Design Equation in Embodiment 1]
A method for deriving the design equation of the balun transformer according to the first embodiment will be described in detail. First, it will be described that the equivalent circuit of the balun transformer shown in FIG.
When the circuit diagram of FIG. 1 is represented by an equivalent circuit, the coupled transmission line 111 can be disassembled into N coupled transmission lines 80 and 81 as shown in FIG. Here, it is assumed that the line width of each line is W, the distance between the lines is S, and the cross section of the coupled transmission line 80 is represented by a capacity model as shown in FIG. C ₃ is a capacitance when the line and the ground form a parallel plate capacitance, C ₄ is a capacitance between the line and the ground leaking from the parallel plate between the coupled transmission lines, and C ₅ is between the coupled transmission lines. , C ₆ is the capacitance between the line leaking from the outer parallel plate and the ground, and the connection line is equipotential. Furthermore, when all the lines are divided in half, it can be expressed as shown in FIG. Since equipotentials can be freely changed, it is considered that they are changed as shown in FIG. In FIG. 6, 91a is equivalent to a microstrip line having a line width W, and 91b, 92b,..., 9 (N−1) b are coupled transmission lines having a line width W and a distance between lines S. This is equivalent to periodically arranging N-1. Therefore, the circuit diagram of FIG. 1 can be represented by the equivalent circuit of FIG.

  Next, the derivation of the design equation of the balun transformer of the first embodiment using the equivalent circuit diagram of FIG. 2 will be described. First, consider the circuit equation of the coupled transmission line 80. As shown in FIG. 7, 14 nodes (nodes 1 a to 6 a, 1 b to 4 b, X, Y) are given to the coupled transmission line 80. Consider the relationship between the current and voltage at each node. Since the transmission line 31 is a microstrip line, the relationship of the following equation (3) is established.

  Here, the following equation (4) is considered.

  The coupled transmission line 51 can be expressed by the following equation (5) from the coupled line theory.

  Here, the following equation (6) is considered.

  When 2θ ≦ 1 [rad], the expression (5) is expanded to the first-order term of θ to be the following expression (7).

  Moreover, the voltage and current of the impedance converters 61 to 64 are expressed by the following equation (8).

  Further, at nodes X and Y, the following equation (9) is obtained from Kirchhoff's law and the relational expression of voltage.

  By arranging the above, the circuit equation of the coupled transmission line 80 can be expressed as in Expression (10).

  Here, the following equation (11) is considered.

  Since the circuit equation of the coupled transmission line 80 is obtained, the equivalent circuit diagram of the balun transformer of the first embodiment can be simplified as shown in FIG. In FIG. 8, eight nodes (1c to 8c) are given. From the voltage relational expression, the following expression (12) is obtained.

  Applying Kirchhoff's law, the following equation (13) is obtained.

Furthermore, when the admittance that anticipates the coupled transmission line 80 side from the node 1c is Y _in , it is expressed by the following equation (14).

  Here, the admittance of the balanced terminal is expressed by the following equation (15).

  By solving the equations (10) to (15), the above equation (1) is obtained.

Further, the load admittance Y ^′ _S that expects the unbalanced terminal P1 side from the terminal 1 is selected so as to be complex conjugate matched to Y _in at the design frequency f ₀ . That is, Y ^′ _S can be expressed by the above-described formula (2).

(Specific example of Embodiment 1)
As an example, for the purpose of use in an output matching circuit of a CMOS (complementary metal oxide semiconductor) push-pull power amplifier, simulation was performed under the following conditions, and a balun transformer was fabricated on a CMOS to confirm the effectiveness of the present invention.
Design frequency: f ₀ = 2.0 [GHz]
Unbalanced terminal admittance: Y _S = 20 [mS]
Balanced terminal admittance: Y _L = 60 + j25f [mS] (f is frequency, unit GHz)
Capacity: C ₁ = 1.5 [pF]
Capacity: C ₂ = 2.1 [pF]
In this trial manufacture, the number N of transmission lines is three, and the capacitors C ₁ and C ₂ are used for impedance matching. FIG. 9 is a circuit structure diagram of a balun transformer having three transmission lines N. In FIG.
In addition, assuming that a balun transformer is formed in an IC (integrated circuit), a case where a transmission line is configured using a side-coupled transmission line formed on a silicon substrate will be described.

FIG. 10 shows a cross-sectional structure of a side-coupled transmission line provided on the upper surface portion of the silicon substrate. The line width of the transmission lines 11, 12, 13 is W, and the distance between two adjacent transmission lines is S. These are provided on the dielectric 302 (oxide film) formed on the upper surface of the dielectric 301 (semiconductor substrate). It has been. Note that the thickness of the transmission line is T.
Using a three-dimensional electromagnetic field simulator, even mode admittance Y ^′ _oe and odd mode admittance Y ^′ _oo of the periodic structure coupled transmission line are calculated using the sectional structure parameters W and S of the coupled transmission line as parameters. Moreover, to calculate the characteristic admittance Y _O of the microstrip line of the line width W. Further, the input admittance Y _in of the balun transformer viewed from the unbalanced terminal P1 is calculated from the equation (2), and the circuit dimensions and the electrical length θ are calculated so as to perform complex conjugate matching with the load Y _S connected to the unbalanced terminal P1. The values of the capacitors C ₁ and C ₂ are determined.
The following are the design results used in this example.
Y _^'oo = 49.2 [mS]
Y ^′ _oe = 1.0 [mS]
Y 2 _O = 10.0 [mS]
W = 30 [μm]
S = 5 [μm]
θ = 6 [deg]

Measurement results actually produced using this design result and equivalent circuit simulation results are shown in FIGS.
From this result, the measurement result and the equivalent circuit simulation result are in good agreement, the voltage reflection characteristic of the unbalanced terminal is −20 dB or less near the design center frequency (2.0 GHz), and the voltage from the unbalanced terminal to the balanced terminal It can be seen that the transfer characteristics are of opposite phase and the same amplitude, and good balun transformer characteristics can be secured. Therefore, the effectiveness of the design equation (2) was shown.
Note _{here, S 11} is the voltage reflection characteristics of the unbalanced terminal _{P1, S 21} the voltage transfer characteristics of the balanced terminals P2 from the unbalanced terminal _{P1, S 31} is the voltage transfer characteristic of the balanced terminal P3 from the unbalanced terminal P1 is there.

Embodiment 2. FIG.
A balun transformer 1000 according to the second embodiment of the present invention will be described. FIG. 14 is a circuit structure diagram of the balun transformer 1000 according to the second embodiment.
The balun transformer 1000 is an electric circuit that converts an input unbalanced signal into a balanced signal that is 180 degrees out of phase, and is an electric circuit that converts the impedance of the unbalanced terminal and the balanced terminal.
Balun transformer 1000, admittance _Y is _S unbalanced terminal P1, admittance _{Y L} a is balanced terminals P2, P3, (the N odd, N ≧ 3) Nos. 1 through N transmission line 11, 12, & -1N is provided. Transmission lines 11, 12,..., 1N have a line width of W, and these lines are periodically arranged at intervals S (left and right or up and down), and adjacent lines are electromagnetically coupled to each other. A transmission line 211 is configured. , 1N, that is, odd-numbered transmission lines 11, 13,..., 1N are connected to each other at terminals 1 and 2, and second, 4,. The transmission line of (N-1), that is, the even-numbered transmission lines 12, 14,..., 1 (N-1) are connected to each other by terminals 3 and 4. Insertion loss can be reduced by increasing the number N of transmission lines. Also, optimum impedance conversion can be performed.

Although FIG. 14 shows a balun transformer in which the terminals 3 and 4 are provided at the right side position, the terminals 3 and 4 may be provided at any position according to the application. The terminal 1 is connected to the unbalanced terminal P1, which is the first load, and the terminal 2 is short-circuited to the ground. Terminals 3 and 4 are connected to balanced terminals P2 and P3, which are second and third loads, respectively. A capacitor C1 is connected in parallel to the unbalanced terminal P1, and a capacitor C2 is connected between the balanced terminals P2 and P3. Note that the capacitor C ₁ and the capacitor C ₂ do not have to be connected, and when not connected, C ₁ = 0 or C ₂ = 0. Transmission lines 11, 12, ..., the line length of 1N (electrical length) is 2θ ≦ 1 [rad] with respect to the design frequency _{f 0.} 14 is an octagonal shape, the shape of the balun transformer 1000 may be any polygon, circle, or straight line.

FIG. 15 is an equivalent circuit diagram of the balun transformer 1000 according to the second embodiment. The coupled transmission line 211 shown in FIG. 14 has coupled transmission lines 51 and 52 whose even mode characteristic admittance is Y ^′ _oe , odd mode characteristic admittance is Y ^′ _oo , the line length is θ, the characteristic admittance is Y _O , and the line length is θ. Transmission lines 31 and 32, and impedance transformers 61 to 68 having an impedance transformation ratio of 1: √ {(N−1) / 2}. Here, Y ^′ _oe and Y ^′ _oo are even-mode characteristic admittance and odd mode of a periodically coupled transmission line that is periodically arranged with a line width W and a line interval S and electromagnetically couples between adjacent lines. It is characteristic admittance. Y _O is the characteristic admittance of a microstrip line having a line width W.
From the equivalent circuit, the input admittance Y _in looking into the balun transformer side from the terminal 1 can be expressed by the following equation (16).

On the other hand, the load admittance Y ^′ _S that expects the unbalanced terminal P1 side from the terminal 1 is selected so as to be complex conjugate matched to Y _in at the design frequency f ₀ . That is, Y ^′ _S can be expressed by the following equation (17).

  Since the circuit element used in the equivalent circuit of FIG. 15 is provided in a general commercially available circuit simulator, the second embodiment of the present invention is characterized in that it can be calculated by the circuit simulator.

  The design equations in the second embodiment can be derived in the same manner as in the first embodiment.

Embodiment 3 FIG.
First, the balun transformer 1000 according to the third embodiment of the present invention will be described. FIG. 16 is a circuit structure diagram of the balun transformer 1000 according to the third embodiment.
The balun transformer 1000 is an electric circuit that converts an input unbalanced signal into a balanced signal that is 180 degrees out of phase, and is an electric circuit that converts the impedance of the unbalanced terminal and the balanced terminal.
Balun transformer 1000, admittance _Y is _S unbalanced terminal P1, admittance _{Y S} a is balanced terminals P2, P3, (the N an even number, N ≧ 4) the N from the first transmission line 11, 12, & -1N is provided. Transmission lines 11, 12,..., 1N have a line width of W, and these lines are periodically arranged at intervals S (left and right or up and down), and adjacent lines are electromagnetically coupled to each other. A transmission line 311 is configured. The first, third,..., N-1 transmission lines, that is, odd-numbered transmission lines 11, 13,. , N, that is, the even-numbered transmission lines 12, 14,..., 1N are connected to each other at terminals 3 and 4, respectively. Insertion loss can be reduced by increasing the number N of transmission lines. In addition, optimum impedance conversion can be performed.

Although FIG. 16 shows a balun transformer in which the terminals 3 and 4 are provided at the right side position, the terminals 3 and 4 may be provided at any position according to the application. The terminal 1 is connected to the unbalanced terminal P1, which is the first load, and the terminal 2 is short-circuited to the ground. Terminals 3 and 4 are connected to balanced terminals P2 and P3, which are second and third loads, respectively. A capacitor C ₁ is connected in parallel to the unbalanced terminal P1, and a capacitor C ₂ is connected between the balanced terminals P2 and P3. Note that the capacitor C ₁ and the capacitor C ₂ do not have to be connected, and when not connected, C ₁ = 0 or C ₂ = 0. Transmission lines 11, 12, ..., the line length of 1N (electrical length) is 2θ ≦ 1 [rad] with respect to the design frequency _{f 0.} 16 is an octagonal shape, the shape of the balun transformer 1000 may be any polygon, circle, or straight line.

FIG. 17 is an equivalent circuit diagram of the balun transformer 1000 according to the first embodiment. The coupled transmission line 311 shown in FIG. 16 has coupled transmission lines 51 and 52 whose even mode characteristic admittance is Y ^′ _oe , odd mode characteristic admittance is Y ^′ _oo , the line length is θ, the characteristic admittance is Y _O , and the line length is θ. Transmission lines 31 to 34, impedance transformers 61 to 68 having an impedance transformation ratio of 1: √ {(N−1) / 2}, and impedance converters 71 to 78 having a ratio of 1: 1 / √2. it can. Here, Y ^′ _oe and Y ^′ _oo are even-mode characteristic admittance and odd mode of a periodically coupled transmission line that is periodically arranged with a line width W and a line interval S and electromagnetically couples between adjacent lines. It is characteristic admittance. Y _O is the characteristic admittance of a microstrip line having a line width W.
From the equivalent circuit, the input admittance Y _in looking into the balun transformer side from the terminal 1 can be expressed by the following equation (18).

On the other hand, the load admittance Y ^′ _S that expects the unbalanced terminal P1 side from the terminal 1 is selected so as to be complex conjugate matched to Y _in at the design frequency f ₀ . That is, Y ^′ _S can be expressed by the following equation (19).

  Since the circuit element used for the equivalent circuit of FIG. 17 is provided in a general commercially available circuit simulator, the third embodiment of the present invention is characterized in that it can be calculated by the circuit simulator.

  The derivation of the design equation in the third embodiment can be derived in the same manner as in the first embodiment.

Embodiment 4 FIG.
A balun transformer 1000 according to Embodiment 4 of the present invention will be described. FIG. 18 is a circuit structure diagram showing a schematic configuration of the balun transformer 1000 according to the fourth embodiment.
The balun transformer 1000 is an injection extraction that injects or extracts the second harmonic into the midpoint of the transmission line connected to the terminals 3 and 4 of the balun transformer 1000 in the first embodiment, the second embodiment, or the third embodiment. The balun transformer is characterized in that a terminal P4 is provided.
FIG. 18 shows a case where the present embodiment is applied to the balun transformer 1000 according to the third embodiment. However, the present embodiment can be similarly applied to the balun transformer according to the first or second embodiment.

Embodiment 5 FIG.
A power amplifier according to Embodiment 5 of the present invention will be described. FIG. 19 is a circuit structure diagram showing a schematic configuration of a power amplifier in which the power amplifier 2000 according to the fifth embodiment is configured using the balun transformer according to the present invention.
The power amplifier 2000 is combined using the balun transformer in the fourth embodiment and one of the balun transformers in the first, second, third, and fourth embodiments, and between balanced terminals. A power amplifier loaded with the amplifying element A1, which is a high-efficiency, low-distortion power amplifier that receives a fundamental wave from a fundamental wave terminal and performs a reflection process or a second harmonic injection extraction on a second harmonic terminal. .
FIG. 19 shows an embodiment configured by using the balun transformer in which the fourth embodiment is applied to the balun transformer 1000 in the first embodiment and the balun transformer 1000 in the second embodiment. The balun transformer in can also be combined as appropriate.
Since the second harmonic terminal is isolated from the fundamental wave terminal, the second harmonic can be reflected or extracted by injection without changing the matching of the fundamental wave.
Therefore, it is possible to increase the efficiency and reduce the distortion of the power amplifier by the second harmonic reflection processing or injection extraction.

Embodiment 6 FIG.
A power amplifier according to Embodiment 6 of the present invention using the balun transformer of the present invention will be described. FIG. 20 is a circuit structure diagram showing a schematic configuration in the case where the power amplifier 3000 according to the sixth embodiment is a power amplifier configured using the balun transformer according to the present invention.
The power amplifier 3000 is a power amplifier in which the two balun transformers in the fourth embodiment are used and the amplification element A1 is loaded between the balanced terminals. The fundamental wave is input from the fundamental wave terminal, and the secondary harmonic terminal is the terminal. A second harmonic feedback high-efficiency / low distortion power amplifier with a second harmonic amplitude / phase adjustment circuit APA loaded in between.
FIG. 20 shows an embodiment configured by using a balun transformer in which the fourth embodiment is applied to the balun transformer 1000 in the first embodiment and a balun transformer in which the fourth embodiment is applied to the balun transformer 1000 in the second embodiment. Although it is a form, the balun transformer which applied Embodiment 4 to other Embodiment can also be combined suitably.
Since the second harmonic terminal is isolated from the fundamental wave terminal, the second harmonic can be fed back without changing the matching of the fundamental wave. Therefore, the efficiency of the power amplifier and the distortion can be reduced by the second harmonic feedback.

  The present invention can be freely combined with each other within the scope of the invention, or can be appropriately modified or omitted.

1 to 4 terminals, 1a to 6a, 1b to 4b, 1c to 8c, X, Y node P1 unbalanced terminal, P2 balanced terminal, P3 balanced terminal, P4 injection extraction terminal, 11 to 1N, 31, 32, 41 to 44 transmission line, 51, 52, 80, 81, 111, 211, 311 coupled transmission line, 61-68, 71-78 impedance converter, 91a microstrip line, 91b-9 (N-1) b periodic structure coupled transmission Line, Y _S , Y _L , Y _2S admittance, C ₁ , C ₂ , C ₃ , C ₄ , C ₅ capacitance, A1 amplifying element, APA second harmonic amplitude / phase adjustment circuit, 1000 balun transformer, 2000, 3000 Power amplifier

Claims (6)

A balun transformer configured to include a coupled transmission line having an electrical length of 2θ ≦ 1 [rad] with respect to a fundamental frequency f ₀ of a transmission signal,
The coupled transmission line is composed of N transmission lines (N is an odd number of 3 or more), and adjacent transmission lines are arranged to be electromagnetically coupled to each other,
The coupled transmission line has a first terminal, a second terminal, a third terminal, and a fourth terminal, and the second terminal, the second terminal, and the like are between the first terminal and the second terminal. , N-1 transmission line, and the third terminal and the fourth terminal are connected by the first, third,..., Nth transmission line,
It said first terminal being connected to a first load P1 of admittance Y _S, the second terminal being shorted to ground,
The third terminal, wherein each fourth terminal is connected to the admittance Y second load _L P2 and third load P3, second load P2, the third load P3 form a balanced terminal cage, the capacitor C ₁ is connected to the first terminal between the terminals of the second terminal, the capacitance C ₂ is connected between the terminals of the third terminal and the fourth terminal,
Transmission line constituting the coupled transmission line is, the even mode characteristic admittance when the periodic structure is coupled transmission line electromagnetically coupled to each other between adjacent lines ^'and _oe, the odd mode characteristic admittance ^Y' Y _oo age,
Transmission line constituting the coupled transmission line has a characteristic admittance of the case of the microstrip line adapted to each other adjacent lines are not electromagnetically coupled to each other and Y _O,
The values of the even mode characteristic admittance Y ^′ _oe , the odd mode characteristic admittance Y ^′ _oo , the characteristic admittance Y _O , the electrical length θ, the capacitance C ₁ and the capacitance C ₂ are the admittance Y _L and the admittance Y _S. Is selected so as to satisfy the following relational expression:

A balun transformer configured to include a coupled transmission line having an electrical length of 2θ ≦ 1 [rad] with respect to a fundamental frequency f ₀ of a transmission signal,
The coupled transmission line is composed of N transmission lines (N is an odd number of 3 or more), and adjacent transmission lines are arranged to be electromagnetically coupled to each other,
The coupled transmission line has a first terminal, a second terminal, a third terminal, and a fourth terminal, and the first terminal and the second terminal are first, third,... Are connected by an Nth transmission line, and the third terminal and the fourth terminal are connected by a second, fourth,..., N−1th transmission line,
It said first terminal being connected to a first load P1 of admittance Y _S, the second terminal being shorted to ground,
The third terminal, wherein each fourth terminal is connected to the admittance Y second load _L P2 and third load P3, second load P2, the third load P3 form a balanced terminal cage, the capacitor C ₁ is connected to the first terminal between the terminals of the second terminal, the capacitance C ₂ is connected between the terminals of the third terminal and the fourth terminal,
Transmission line constituting the coupled transmission line is, the even mode characteristic admittance when the periodic structure is coupled transmission line electromagnetically coupled to each other between adjacent lines ^'and _oe, the odd mode characteristic admittance ^Y' Y _oo age,
Transmission line constituting the coupled transmission line has a characteristic admittance of the case of the microstrip line adapted to each other adjacent lines are not electromagnetically coupled to each other and Y _O,
The values of the even mode characteristic admittance Y ^′ _oe , the odd mode characteristic admittance Y ^′ _oo , the characteristic admittance Y _O , the electrical length θ, the capacitance C ₁ and the capacitance C ₂ are the admittance Y _L and the admittance Y _S. Is selected so as to satisfy the following relational expression:

A balun transformer configured to include a coupled transmission line having an electrical length of 2θ ≦ 1 [rad] with respect to a fundamental frequency f ₀ of a transmission signal,
The coupled transmission line is composed of N transmission lines (N is an even number of 4 or more), and adjacent transmission lines are arranged to be electromagnetically coupled to each other,
The coupled transmission line has a first terminal, a second terminal, a third terminal, and a fourth terminal, and the first terminal and the second terminal are first, third,... , The N-1th transmission line, and the third terminal and the fourth terminal are connected by the second, fourth,..., Nth transmission line,
It said first terminal being connected to a first load P1 of admittance Y _S, the second terminal being shorted to ground,
The third terminal, wherein each fourth terminal is connected to the admittance Y second load _L P2 and third load P3, second load P2, the third load P3 form a balanced terminal cage, the capacitor C ₁ is connected to the first terminal between the terminals of the second terminal, the capacitance C ₂ is connected between the terminals of the third terminal and the fourth terminal,
Transmission line constituting the coupled transmission line is, the even mode characteristic admittance when the periodic structure is coupled transmission line electromagnetically coupled to each other between adjacent lines ^'and _oe, the odd mode characteristic admittance ^Y' Y _oo age,
Transmission line constituting the coupled transmission line has a characteristic admittance of the case of the microstrip line adapted to each other adjacent lines are not electromagnetically coupled to each other and Y _O,
The even mode characteristic admittance Y ^′ _oe , the odd mode characteristic admittance Y ^′ _oo , the electrical length θ, the capacitance C _1, and the capacitance C ₂ have the following relationship between the admittance Y _L and the admittance Y _S : A balun transformer characterized by being selected to satisfy the formula.

  The injection extraction terminal for injecting or extracting the second harmonic is provided at the midpoint of the transmission line connecting the third terminal and the fourth terminal. Item 4. The balun transformer according to any one of Items 3.   A balun transformer according to claim 4 and a balun transformer according to any one of claims 1 to 4, wherein an amplifying element is provided between balanced terminals, and second harmonics are injected or extracted. A power amplifier for performing power amplification by applying a second harmonic reflection process or a second harmonic injection to an injection extraction terminal. 5. Two balun transformers according to claim 4, wherein an amplifying element is provided between the balanced terminals, and the amplitude and phase of the second harmonic are adjusted between the injection and extraction terminals for injecting or extracting the second harmonic. A power amplifier characterized by loading a circuit and performing power amplification.

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