Transmission line, composite right / left-handed line, composite right / left-handed transmission line, impedance transformation circuit, and distributed amplifier

Abstract

A transmission line according to the present disclosure comprises: a first inductor part (10) having one end connected to a first terminal (1) and the other end connected to a second terminal (2); and a second inductor part (20) having one end connected to the other end of the first inductor part (10) and the other end connected to a third terminal (3). The coupling coefficient between the first inductor part (10) and the second inductor part (20) is a positive value.

Description

Transmission lines, right-handed / left-handed hybrid transmission lines, impedance transformation circuits, and distributed amplifiers.

[0001] This disclosure relates to transmission lines, right-handed / left-handed hybrid transmission lines, impedance transformation circuits, and distributed amplifiers, which are implemented in high-frequency integrated circuits and the like.

[0002] As inductors implemented in high-frequency integrated circuits and the like, they are applied to transmission lines for transmitting high-frequency signals (currents), right-handed / left-handed composite transmission lines, as well as choke coils for bias application in high-frequency amplifiers, impedance transformation circuits, and filter circuits. An example of using a right-handed / left-handed composite transmission line as a transmission line is shown, for example, in Patent Document 1.

[0003] The transmission line described in Patent Document 1 operates as a CRLH transmission line overall, with a transmission section provided on the upper surface of the first substrate, comprising capacitive elements and stubs repeatedly arranged along the longitudinal direction, a grounding section provided on the lower surface of the second substrate, and an inductive element in the shape of a vertically thin, spiral-shaped element provided on the bonding surface between the first and second substrates. By providing an inductive element between the first and second substrates, the space utilization of the transmission line is increased, resulting in miniaturization of the device.

[0004] Special Publication No. 2010-500844

[0005] The transmission line shown in Patent Document 1 has a special shape in which the inductive element is a thin, vertically oriented spiral-shaped element of thin film between a first substrate and a second substrate. This disclosure has been made in view of the above points, and aims to provide a transmission line that can achieve high bandwidth and reduce the occupied area in high-frequency integrated circuits and the like.

[0006] The transmission line according to this disclosure comprises a first inductor section having one end connected to a first terminal and the other end connected to a second terminal, and a second inductor section having one end connected to the other end of the first inductor section and the other end connected to a third terminal, wherein the coupling coefficient between the first inductor section and the second inductor section is a positive value.

[0007] According to this disclosure, since the transmission line has a first inductor section and a second inductor section with a positive coupling coefficient, it is possible to increase the bandwidth and also reduce the size.

[0008] This is a simplified plan view showing a transmission line according to Embodiment 1. This is a plan view showing an example layout for a transmission line according to Embodiment 1. This is a plan view showing another example layout for a transmission line according to Embodiment 1. This is a circuit diagram showing the equivalent circuit of a CRLH line (Application Example 1) to which the transmission line according to Embodiment 1 is applied. This is a diagram showing the frequency-pass characteristics of the transmission bandwidth in a CRLH line (Application Example 1) to which the transmission line according to Embodiment 1 is applied, along with Comparative Examples 1 and 2. This is a diagram showing the frequency-pass characteristics of the transmission bandwidth in a CRLH line (Application Example 1) to which the transmission line according to Embodiment 1 is applied, along with Comparative Example 3. This is a simplified plan view showing a modified inductor according to Embodiment 1 applied to a CRLH line (Application Example 2). This is a diagram showing the frequency-pass characteristics of the transmission bandwidth in a CRLH line (Application Example 1) to which the transmission line according to Embodiment 1 is applied and a CRLH line (Application Example 2) to which a modified version of the transmission line according to Embodiment 1 is applied. This is a block diagram showing the transmission line according to Embodiment 1 applied as an impedance transformation circuit (Application Example 3). This is a circuit diagram showing Application Example 4, in which a CRLH transmission line applying the transmission line according to Embodiment 1 is used in a distributed amplifier. This is a circuit diagram showing a CRLH transmission line (Application Example 5) in which two unit cells of a CRLH transmission line applying the transmission line according to Embodiment 1 are connected. This is a simplified plan view showing the transmission line in Application Example 5. This is a diagram showing the frequency-pass characteristics of the transmission bandwidth in Application Example 5. This is a simplified perspective view showing the transmission line according to Embodiment 2. This is a simplified perspective view showing the transmission line according to Embodiment 3.

[0009] Embodiment 1. The transmission line according to Embodiment 1 will be described with reference to Figure 1. The transmission line according to Embodiment 1 is a transmission line that is mounted on a high-frequency integrated circuit and the like, and is applied to a right-handed / left-handed composite transmission line that transmits high-frequency signals (currents), as well as a choke coil for bias application in a high-frequency amplifier, an impedance transformation circuit, and a filter circuit.

[0010] The transmission line according to Embodiment 1 comprises a first inductor section 10 and a second inductor section 20. The first inductor section 10 is formed in a conductive layer, which is a metal layer on the surface of an insulating substrate, which is a dielectric substrate on which a high-frequency integrated circuit is formed. The dielectric substrate is, for example, a silicon carbide (SiC) substrate.

[0011] The first inductor section 10 has, in the X-Y plane between the X-axis (horizontal direction as shown in Figure 1) and the Y-axis (vertical direction as shown in Figure 1) perpendicular to the X-axis, a first side 11 with a length L2 parallel to the Y-axis extending from one end 10a, a second side 12 with a length L1 parallel to the X-axis extending from the other end of the first side 11, and a third side 13 with a length L2 parallel to the Y-axis extending from the other end of the second side 12 and facing the first side 11. The first inductor section 10 is a U-shaped meander inductor section, and the second side 12 may be curved or semicircular.

[0012] The first side 11, the second side 12, and the third side 13 are arranged counterclockwise, and their respective widths are W. The other end of the first side 11 and one end of the second side 12 are common parts, and the other end of the second side 12 and one end of the third side 13 are also common parts. The center of the region enclosed by the first side 11, the second side 12, and the third side 13 becomes the axis of rotation of the loop-shaped current flowing through the first inductor section 10.

[0013] One end (one end) 10a of the first inductor section 10, that is, one end of the first side 11, is electrically connected to the first terminal 1, and the other end (other end) 10b, that is, the other end of the third side 13, is electrically connected to the second terminal 2. The first terminal 1 is part of a line that is electrically connected to another circuit or circuit element, and the second terminal 2 is part of a line that is electrically connected to another circuit or circuit element.

[0014] The second inductor section 20 is formed in the same metal layer as the first inductor section 10. The second inductor section 20 is formed within the region enclosed by the first side 11, the second side 12, and the third side 13 of the first inductor section 10. The second inductor section 20 is a spiral inductor section. In the X-Y plane, the second inductor section 20 has a first annular section 21, a second annular section 22, and a lead-out section 23.

[0015] The first annular portion 21 is positioned inside the first inductor portion 10 with a gap S between them. The second annular portion 22 is positioned inside the first annular portion 21 with a gap S between them. The lead-out portion 23 is for electrically connecting to the third terminal 3 located outside the first inductor portion 10. Note that the gap S between the first annular portion 21 and the first inductor portion 10 and the gap S between the first annular portion 21 and the second annular portion 22 may be different values.

[0016] The first annular portion 21 has four sides, from the first side 21a to the fourth side 21d, arranged counterclockwise along its four edges. The width of each side from the first side 21a to the fourth side 21d is W. The first annular portion 21 is positioned inside the first inductor portion 10, with each of the second side 21b to the fourth side 21d facing each of the first side 11 to the third side 13 of the first inductor portion 10 with a gap S between them. One end of the first side 21a and the other end of the third side 13 of the first inductor portion 10 are a common portion and serve as a connection node between the first inductor portion 10 and the second inductor portion 20.

[0017] The first side 21a is parallel to the X-axis, and its length from one end (one end) is (L1-W-S). The second side 21b is positioned inside the first side 11 in the first inductor section 10, with a gap S between it and the first side 11, from the other end of the first side 21a, and its length from one end is (L2-W-S).

[0018] The third side 21c is positioned inside the second side 12 of the first inductor section 10, with a gap S between it and the second side 12, extending from the other end of the second side 21b, and the length of the third side 21c from one end is (L1 - 2W - 2S). The fourth side 21d is positioned inside the third side 13 of the first inductor section 10, with a gap S between it and the third side 13, extending from the other end of the third side 21c, and the length of the fourth side 21d from one end is (L2 - 2W - 2S).

[0019] Note that the first annular portion 21 may have an elliptical shape in which the first side 21a and the third side 21c are curved, or may have a circular shape. Further, the widths W of the first side 21a to the fourth side 21d may be different values from the widths W of the first side 11 to the third side 13 in the first inductor portion 10. The other end of the first side 21a and one end of the second side 21b are common parts, the other end of the second side 21b and one end of the third side 21c are common parts, and the other end of the third side 21c and one end of the fourth side 21d are common parts.

[0020] The second annular portion 22 has a first side 22a to a fourth side 22d arranged counterclockwise on four sides. The second annular portion 22 is arranged inside the first annular portion 21, and the first side 22a to the fourth side 22d are respectively arranged to face the first side 21a to the fourth side 21d in the first annular portion 21 with an interval S therebetween. The width of each of the first side 22a to the fourth side 22d is W, which is the same as the width W of each of the first side 21a to the fourth side 21d in the first annular portion 21.

[0021] The first side 22a is arranged from the other end of the fourth side 21d in the first annular portion 21 to the inside of the first side 21a in the first annular portion 21 with an interval S from the first side 21a, and the length from one end of the first side 22a is (L1 - 3W - 3S). One end of the first side 22a and the other end of the fourth side 21d in the first annular portion 21 are common parts, which are connection nodes of the first annular portion 21 and the second annular portion 22. The second side 22b is arranged from the other end of the first side 22a to the inside of the second side 21b in the first annular portion 21 with an interval S from the second side 21b, and the length from one end of the second side 22b is (L2 - 3W - 3S).

[0022] The third side 22c is arranged from the other end of the second side 22b to the inside of the third side 21c in the first annular portion 21 with an interval S from the third side 21c, and the length from one end of the third side 22c is (L1 - 4W - 4S). The fourth side 22d is arranged from the other end of the third side 22c to the inside of the fourth side 21d in the first annular portion 21 with an interval S from the fourth side 21d, and the length from one end of the fourth side 22d is (L2 - 4W - 4S).

[0023] Incidentally, the second annular portion 22 may be an elliptical shape in which the first side 22a and the third side 22c are curved, or may be a circular shape. The other end of the first side 22a and one end of the second side 22b are common portions, the other end of the second side 22b and one end of the third side 22c are common portions, and the other end of the third side 22c and one end of the fourth side 22d are common portions.

[0024] The lead-out portion 23 has an L-shape having a first side 23a and a second side 23b in the counterclockwise direction. The lead-out portion 23 is disposed inside the second annular portion 22, and the first side 23a and the second side 23b are respectively disposed to face the first side 22a and the second side 22b in the second annular portion 22 with an interval S therebetween.

[0025] The first side 23a is disposed from the other end of the fourth side 22d in the second annular portion 22 to the inside of the first side 22a in the second annular portion 22 with an interval S from the first side 22a, and the length from one end of the first side 23a is (L1 - 5W - 5S). The second side 23b is disposed from the other end of the first side 23a to the inside of the second side 22b in the second annular portion 22 with an interval S from the second side 22b, and the length from one end of the second side 23b is (L2 - 2W - 2S).

[0026] The other end of the second side 23b is electrically connected to the third terminal 3 located outside the first inductor portion 10. The interval S between each of the first side 21a to the fourth side 21d in the first annular portion 21 and each of the first side 22a to the fourth side 22d in the second annular portion 22, and the interval S between each of the first side 22a and the second side 22b in the second annular portion 22 and each of the first side 23a and the second side 23b in the lead-out portion 23 may be different values from the interval S between each of the first side 11 to the third side 13 in the first inductor portion 10 and each of the second side 21b to the fourth side 21d in the second annular portion 22.

[0027] The portion where the second side 23b in the lead-out portion 23 intersects with the second side 12 in the first inductor portion 10, the third side 21c of the first annular portion 21 in the second inductor portion 20, and the third side 22c of the second annular portion 22 is intersected by air bridges in the second side 12, the third side 21c, and the third side 22c.

[0028] One end (one end) 20a of the second inductor section 20, that is, one end of the first side 21a of the first annular section 21, is electrically connected to the second terminal 2 and the other end (other end) 10b of the first inductor section 10, that is, the other end of the third side 13 of the first inductor section 10. The other end (other end) 20b of the second inductor section 20, that is, the second side 23b of the lead-out section 23, is connected to the third terminal 3. One end 20a of the second inductor section 20 and the other end 10b of the first inductor section 10 are common parts and are the connection node between the first inductor section 10 and the second inductor section 20.

[0029] The center of the first annular portion 21 and the center of the second annular portion 22 are the same, and they form the axis of rotation of the loop current flowing through the second inductor portion 20. The direction of rotation of the loop current flowing through the second inductor portion 20 is the same as the direction of rotation of the loop current flowing through the first inductor portion 10.

[0030] The rotation axis and direction of the loop current in the first inductor section 10 are aligned with those of the second inductor section 20, and the coupling coefficient k between the first inductor section 10 and the second inductor section 20 is set to a positive value (k > 0). By setting the coupling coefficient k between the first inductor section 10 and the second inductor section 20 to a positive value, electromagnetic field coupling occurs between the first inductor section 10 and the second inductor section 20. As a result, the bandwidth of the inductor can be increased, and the area occupied by the inductor can be reduced.

[0031] The transmission line according to Embodiment 1 comprises a first inductor section 10 and a second inductor section 20, and is arranged such that the coupling coefficient k of the first inductor section 10 and the second inductor section 20 is a positive value (k > 0), thereby enabling higher bandwidth in the transmission line. By arranging the second inductor section 20 inside the first inductor section 10, the rotation axis and direction of the loop current in the first inductor section 10 and the rotation axis and direction of the loop current in the second inductor section 20 are aligned, thereby reducing the area occupied by the transmission line.

[0032] In Embodiment 1, the first inductor section 10 is formed by a meander inductor section and the second inductor section 20 is formed by a spiral inductor section. However, by increasing or decreasing the rotational speed of the loop-shaped current, the first inductor section 10 may be formed by a spiral inductor section and the second inductor section 20 may be formed by a meander inductor section.

[0033] The operating principle of the transmission line according to Embodiment 1 will be explained using the layout example shown in Figure 2. In the layout example shown in Figure 2, the first terminal 1, second terminal 2, third terminal 3, first inductor section 10, second inductor section 20, and connection nodes 10b and 20a between the first inductor section 10 and the second inductor section 20, as described in Figure 1, function as an input node 1, a first output node 2, a second output node 3, a first inductor 10, a second inductor 20, and connection nodes 10b and 20a between the first inductor 10 and the second inductor 20, respectively.

[0034] The transmission line in the layout example shown in Figure 2 comprises a first inductor 10 shown by a dashed line and a second inductor 20 shown by a solid line. As explained in Figure 1, the first inductor 10 and the second inductor 20 are formed on the same conductive layer (X-Y plane) on the surface of the insulating substrate. The second inductor 20 is positioned inside the first inductor 10.

[0035] As shown by the arrows in Figure 2, a loop current flows through the first inductor 10 from the input node 1 to the first output node 2 due to the high-frequency signal input to the input node 1. The current flowing to the first output node 2 is one of the currents of the high-frequency signal input to the input node 1, which is branched at the connecting nodes 10b and 20a.

[0036] A loop current, branched from the first inductor 10 at connection nodes 10b and 20a and supplied to the second output node 3, flows through the second inductor 20. The current flowing through the second inductor 20 is the other current of the high-frequency signal input to the input node 1, which is branched at connection nodes 10b and 20a.

[0037] The second inductor 20 is placed inside the first inductor 10 in the same conductive layer on which the first inductor 10 is formed. The first inductor 10 is a U-shaped meander inductor. The second inductor 20 is a spiral inductor.

[0038] The axis of rotation and direction of rotation of the loop current in the first inductor 10 are aligned with those of the loop current in the second inductor 20. That is, the direction of flow of the loop current in the first inductor 10 and the direction of flow of the loop current in the second inductor 20 are counterclockwise around the same axis of rotation in Figure 2.

[0039] Since the loop current in the first inductor 10 and the loop current in the second inductor 20 are in the same direction, the magnetic field created by the first inductor 10 and the magnetic field created by the second inductor 20 are in the same direction, and the coupling coefficient k of the first inductor 10 and the second inductor 20 becomes a positive value (k > 0). As a result, the transmission line according to this disclosure can be made to have a high bandwidth, and the area occupied by the transmission line can be reduced.

[0040] Other Layout Examples Another layout example of the transmission line according to Embodiment 1 will be explained with reference to Figure 3. The transmission line in the other layout example shown in Figure 3 is an example in which the input terminals and output terminals are swapped with the transmission line in the layout example shown in Figure 2, and the transmission line in the other layout example shown in Figure 3 has the same effect as the transmission line in the layout example shown in Figure 2.

[0041] In the example layout shown in Figure 3, the transmission line consists of the first terminal 1, the second terminal 2, the third terminal 3, the first inductor section 10, the second inductor section 20, and the connection nodes 10b and 20a between the first inductor section 10 and the second inductor section 20, respectively, as described in Figure 1.

[0042] In the other layout example shown in Figure 3, the transmission line comprises a first inductor 20 shown by a solid line and a second inductor 10 shown by a dashed line. A loop current flows through the first inductor 20 from the input node 3 to the first output node 2 due to the high-frequency signal input to the input node 3, as shown by the arrows in Figure 3. The current flowing to the first output node 2 is one of the currents of the high-frequency signal input to the input node 3, which is branched at connection nodes 20a and 10b.

[0043] A loop current, branched from the first inductor 20 at connection nodes 20a and 10b, flows through the second inductor 10 due to a high-frequency signal directed to the second output node 1. The current flowing through the second inductor 10 is the other current of the high-frequency signal input to the input node 3, which is branched at connection nodes 20a and 10b.

[0044] The first inductor 20 is placed inside the second inductor 10 in the same conductive layer on which the second inductor 10 is formed. The first inductor 20 is a spiral inductor. The second inductor 10 is a U-shaped meander inductor.

[0045] The axis of rotation and direction of rotation of the loop current in the first inductor 20 are aligned with those of the loop current in the second inductor 10. That is, the direction of flow of the loop current in the first inductor 20 and the direction of flow of the loop current in the second inductor 10 are clockwise around the same axis of rotation in Figure 3.

[0046] Since the loop current in the first inductor 20 and the loop current in the second inductor 10 are in the same direction, the magnetic field created by the first inductor 20 and the magnetic field created by the second inductor 10 are in the same direction, and the coupling coefficient k of the first inductor 20 and the second inductor 10 becomes a positive value (k > 0). As a result, the transmission line according to this disclosure can be made to have a higher bandwidth, and the area occupied by the transmission line can be reduced.

[0047] Application Example 1. The case in which the transmission line according to Embodiment 1 shown in Figure 1 is applied to a composite right-and-left-handed line (hereinafter referred to as a CRLH line) will be explained using Figure 4. When applied to a CRLH line, the first terminal 1, second terminal 2, third terminal 3, first inductor section 10, second inductor section 20, and connection nodes 10b and 20a between the first inductor section 10 and the second inductor section 20, as shown in Figure 1, function as input node 1, output node 2, ground node 3, first inductor 10, second inductor 20, and connection nodes 10b and 20a between the first inductor 10 and the second inductor 20, respectively.

[0048] As shown in Figure 4, the CRLH transmission line comprises a left-handed series capacitor 30, a right-handed series inductor 10, a left-handed parallel inductor 20, and a right-handed parallel capacitor 40. The right-handed series inductor 10 and the right-handed parallel capacitor 40 constitute a right-handed transmission line having transmission characteristics in the high-frequency region, which is the right-handed transmission bandwidth, while the left-handed series capacitor 30 and the left-handed parallel inductor 20 constitute a left-handed transmission line having transmission characteristics in the low-frequency region, which is the left-handed transmission bandwidth.

[0049] The first inductor 10 and the second inductor 20 are used as a right-handed series inductor 10 and a left-handed parallel inductor 20, respectively, enclosed by dashed lines in Figure 4. The left-handed series capacitor 30 is connected in series with the right-handed series inductor 10 between the input terminal of the CRLH line to which the input signal is input and the input node 1, that is, between one end 10a of the right-handed series inductor 10. The right-handed parallel capacitor 40 is connected in parallel with the left-handed parallel inductor 20.

[0050] The coupling coefficient k of the right-handed series inductor 10 and the left-handed parallel inductor 20 is a positive value (k > 0), and the axis and direction of rotation of the loop current in the right-handed series inductor 10 are aligned with the axis and direction of rotation of the loop current in the left-handed parallel inductor 20. The right-handed series inductor 10 is a meander inductor with a counterclockwise U-shape. The left-handed parallel inductor 20 is a spiral inductor with a counterclockwise spiral shape.

[0051] The left-handed series capacitor 30 and the right-handed parallel capacitor 40 are each mounted on a high-frequency integrated circuit together with the right-handed series inductor 10 and the left-handed parallel inductor 20, and are MIM (Metal-Insulator-Metal) capacitors or IDT (Interdigital) capacitors. Furthermore, in a high-frequency amplifier, when the CRLH transmission line of this disclosure is used, the stray capacitance of the FETs constituting the high-frequency amplifier may be used for the left-handed series capacitor 30 and the right-handed parallel capacitor 40, respectively.

[0052] Now, the inductance of the right-handed series inductor 10 is L Ｒ The inductance of the left-handed parallel inductor 20 is L Ｌ The capacitance of the left-handed series capacitor 30 is C Ｌ The capacitance of the right-handed parallel capacitor 40 is C Ｒ Let M be the mutual inductance between the right-handed series inductor 10 and the left-handed parallel inductor 20. The mutual inductance M can be expressed by the following equation (1).

[0053] In equation (1) above, k is the coupling coefficient between the right-handed series inductor 10 and the left-handed parallel inductor 20.

[0054] In the CRLH transmission line described in this disclosure, the coupling coefficient k is a positive value (k > 0), so the mutual inductance M is a positive value (M > 0). Generally known CRLH transmission lines have a coupling coefficient k of 0 and a mutual inductance M of 0.

[0055] The transfer function G(jω) in the CRLH line in this disclosure is given by the input voltage Vｉｎ and the output voltage V ｏｕｔ can be represented by the ratio of, and can be expressed by the following formula (2).

[0056] In the above formula (2), ω is the angular frequency.

[0057] In the CRLH line in the present disclosure, the input voltage V ｉｎ and the output voltage V ｏｕｔ The cut-off frequency at which the voltage amplitude ratio becomes 1 / A is f － f ＋ Let it be, then the cut-off frequency f － can be expressed by the following formula (3), and the cut-off frequency f － can be expressed by the following formula (4).

[0058]

[0059] In the above formula (3) and the above formula (4), a is the following formula (5), Δa is the following formula (6), b is the following formula (7), and Δb is the following formula (8). a = C Ｒ C Ｌ L Ｒ L Ｌ　　 ...(5) Δa = C Ｒ C Ｌ M ２　　　 ...(6) b = C Ｌ L Ｌ (A + 1) + C Ｒ L Ｌ + C Ｌ L Ｒ　　　　　 ...(7) Δb = C Ｌ M(A + 2)...(8)

[0060] At frequencies lower than the cut-off frequency f － and frequencies higher than the cut-off frequency f － the voltage amplitude ratio (V ｏｕｔ / V ｉｎ ) becomes 1 / A or less. Therefore, the transmission band Δf ２ in the CRLH line in the present disclosure can be expressed by the following formula (9).

[0061]

[0062] In addition, in a commonly known CRLH transmission line, the mutual inductance M is 0, so Δa and Δb are 0, and the transmission bandwidth Δf １ This can be expressed by the following equation (9).

[0063]

[0064] In equation (9) above, since the mutual inductance M is a positive value (M > 0), Δa is also a positive value (Δa > 0) and Δb is also a positive value (Δb > 0). Therefore, comparing equation (9) and equation (10) above, Δf ２ >Δf １ This means that the transmission bandwidth Δf in the CRLH line in this disclosure. ２ The transmission bandwidth Δf in a commonly known CRLH line is １ It has a wider frequency bandwidth that can be transmitted.

[0065] Next, Figure 5 shows the simulation results of the pass-through characteristic S21 (dB) with respect to the input signal frequency in the CRLH transmission line. The conditions for the CRLH transmission line to obtain the simulation results shown in Figure 5 are as follows: The input load and output load of the CRLH transmission line are both set to 50Ω, and L Ｒ = 0.5 nH, C Ｒ = 0.5 pF, C Ｌ = 1 pF, L Ｌ The pH was set to 1. Furthermore, the capacitance values ​​of the left-handed series capacitor 30 and the right-handed parallel capacitor 40 were set to represent ideal components in the circuit simulator.

[0066] In Figure 5, the horizontal axis represents the frequency of the input signal, and the vertical axis represents the pass-through characteristic S21. The solid line E is characteristic curve E showing the calculation result of the CRLH transmission line in this disclosure with a coupling coefficient k of +0.2 (k = 0.2), the dashed line S1 is characteristic curve S1 of Comparative Example 1 showing the calculation result of a generally known CRLH transmission line with a coupling coefficient k of 0 (k = 0), and the dotted line S2 is characteristic curve S2 of Comparative Example 2 showing the calculation result of a CRLH transmission line with a coupling coefficient k of -0.2 (k = -0.2) where the magnetic field created by the right-handed series inductor 10 and the magnetic field created by the left-handed parallel inductor 20 are in opposite directions.

[0067] As is clear from Figure 5, the transmission bandwidth of the CRLH line of this disclosure is wider than that of the CRLH lines of Comparative Examples 1 and 2. Furthermore, as is clear from the above equation, the CRLH line of this disclosure is load-independent and has a wider transmission bandwidth than a generally known CRLH line (k=0) for any parameter (Δf ２ >Δf １ ) This reveals that.

[0068] Furthermore, Figure 6 shows the comparison results with Comparative Example 3, in which the coupling coefficient k obtained by the following method is 0. Specifically, in Comparative Example 3, the electromagnetic fields of the right-handed series inductor 10 and the left-handed parallel inductor 20 were calculated separately, with the connection nodes 10b and 20a as the boundary. By calculating the electromagnetic fields of the right-handed series inductor 10 and the left-handed parallel inductor 20 separately, it is possible to reproduce a situation in which the magnetic field created by one inductor does not affect the other inductor, that is, a situation in which there is no effect of electromagnetic field coupling and the coupling coefficient k = 0.

[0069] The conditions for the CRLH transmission line to obtain the simulation results shown in Figure 6 are as follows: A right-handed series inductor 10 and a left-handed parallel inductor 20 are formed on the surface of a SiC substrate in the shape shown in Figure 1, with L1 = 260 μm, L2 = 340 μm, W = 20 μm, and S = 20 μm.

[0070] The self-inductance of the CRLH transmission line in this disclosure and Comparative Example 3 are set to be the same, and simulation results of the pass-through characteristic S21 (dB) with respect to the input signal frequency are obtained. Furthermore, the capacitance values ​​of the left-handed series capacitor 30 and the right-handed parallel capacitor 40 are set to ideal components in the circuit simulator.

[0071] In Figure 6, the horizontal axis represents the frequency of the input signal, and the vertical axis represents the pass-through characteristic S21. The solid line E is the characteristic curve E showing the calculation result of the CRLH transmission line in this disclosure with a coupling coefficient k of +0.2 (k = 0.2), and the dashed line S3 is the characteristic curve S3 of Comparative Example 3 showing the calculation result of the CRLH transmission line of Comparative Example 3.

[0072] As is clear from Figure 6, the transmission bandwidth of the CRLH line in this disclosure is wider than that of the CRLH line in Comparative Example 3. In other words, even if the self-inductance values ​​of the right-handed series inductor 10 and the left-handed parallel inductor 20 are the same, by setting the coupling coefficient k between the right-handed series inductor 10 and the left-handed parallel inductor 20 to a positive value (k > 0), the electromagnetic field coupling generated between the right-handed series inductor 10 and the left-handed parallel inductor 20 can be utilized, thereby widening the transmission bandwidth.

[0073] In application example 1, which was applied to a CRLH transmission line, the right-handed series inductor 10 was formed using a meander inductor and the left-handed parallel inductor 20 using a spiral inductor. However, by increasing or decreasing the rotation speed of the loop current, the right-handed series inductor 10 may be formed using a spiral inductor and the left-handed parallel inductor 20 using a meander inductor.

[0074] Application Example 2. This differs from the CRLH transmission line shown in Application Example 1 in that the configuration of the first inductor 10 and the second inductor 20 is as shown in Figure 7. The first inductor 10, a right-handed series inductor 10, has, in the X-Y plane, a first side 11 with a length of (L'2 - W - S) parallel to the Y axis from one end 10a, a second side 12 with a length of (L'2 - W - S) parallel to the Y axis from the other end of the first side 11, opposite the first side 11 with a gap S, and a third side 13 with a length of (L'1 - W - S) parallel to the X axis from the other end of the second side 12. Length L'1 is the same as length L1 in Application Example 1, and length L'2 is longer than length L2 in Application Example 1. The width of the first side 11, the second side 12, and the third side 13 is W.

[0075] One end (one end) 10a of the right-handed series inductor 10, that is, one end of the first side 11, is electrically connected to the other electrode of the left-handed series capacitor 30, one of which is electrically connected to the input terminal of the CRLH line. The other end (other end) 10b of the right-handed series inductor 10, that is, the other end of the third side 13, is electrically connected to the output node 2.

[0076] The second inductor 20, a left-handed parallel inductor 20, is formed in the same metal layer as the right-handed series inductor 10. The left-handed parallel inductor 20 has a first annular portion 21, a second annular portion 22, and a lead portion 23 in the X-Y plane. The first annular portion 21 has four sides, from the first side 21a to the fourth side 21d. The width of each side from the first side 21a to the fourth side 21d is W.

[0077] One end of the first side 21a and the other end of the third side 13 in the right-handed series inductor 10 are common parts and are the connection node between the right-handed series inductor 10 and the left-handed parallel inductor 20. The first side 21a is parallel to the Y axis, and the length from one end of the first side 21a is (L'2 - W - S). The second side 21b is parallel to the X axis from the other end of the first side 21a, and the length from one end of the second side 21b is (L'1 - 2W - 2S).

[0078] The third side 21c is positioned opposite the second side 12 of the right-handed series inductor 10 with a gap S between it and the other end of the second side 21b, and the length of the third side 21c from one end is (L'2 - 2W - 2S). The fourth side 21d is positioned opposite the third side 13 of the right-handed series inductor 10 with a gap S between it and the other end of the third side 21c, and the length of the fourth side 21d from one end is (L'1 - 3W - 3S).

[0079] The second annular portion 22 has four sides, from the first side 22a to the fourth side 22d. The second annular portion 22 is located inside the first annular portion 21, with each of the first side 22a to the fourth side 22d facing each of the first side 21a to the fourth side 21d in the first annular portion 21, separated by a gap S. The width of each of the first side 22a to the fourth side 22d is W, which is the same as the width W of each of the first side 21a to the fourth side 21d in the first annular portion 21.

[0080] The first side 22a is positioned inside the first side 21a in the first annular portion 21, from the other end of the fourth side 21d in the first annular portion 21, with a gap S between it and the first side 21a, and the length of the first side 22a from one end is (L'2 - 3W - 3S). One end of the first side 22a is electrically connected to the output node 2. The second side 22b is positioned inside the second side 21b in the first annular portion 21, from the other end of the first side 22a, with a gap S between it and the second side 21b, and the length of the second side 22b from one end is (L'1 - 4W - 4S).

[0081] The third side 22c is positioned inside the third side 21c in the first annular portion 21, with a gap S between it and the other end of the second side 22b, and the length of the third side 22c from one end is (L'2 - 4W - 4S). The fourth side 22d is positioned inside the fourth side 21d in the first annular portion 21, with a gap S between it and the other end of the third side 22c, and the length of the fourth side 22d from one end is (L'1 - 5W - 5S).

[0082] The pull-out section 23 has an L-shape with a first side 23a and a second side 23b. The first side 23a is positioned inside the first side 22a of the second annular section 22, from the other end of the fourth side 22d of the second annular section 22, with a gap S between the first side 22a and the second side 23a, and the length of the first side 23a from one end is (L'2 - 2W - 2S).

[0083] The second side 23b is positioned outside the second side 21b in the first annular portion 21, with a gap S between it and the second side 212b, extending from the other end of the first side 23a, and the length of the second side 23b from one end is (L'1 - 4W - 4S). The other end of the second side 23b is electrically connected to the ground node 3.

[0084] The portion where the first side 23a of the lead-out section 23 intersects with the second side 21b of the first annular section 21 and the second side 22b of the second annular section 22 of the second inductor section 20 is intersected by an air bridge on the second side 21b and the second side 22b.

[0085] One end (one end) 20a of the left-handed parallel inductor 20, that is, one end of the first side 21a of the first annular portion 21, is electrically connected to the output node 2 and the other end (other end) 10b of the right-handed series inductor 10, that is, the other end of the third side 13 of the right-handed series inductor 10.

[0086] The other end (other end) 20b of the left-handed parallel inductor 20, that is, the second side 23b of the lead-out portion 23, is connected to the ground node 3. One end 20a of the left-handed parallel inductor 20 and the other end 10b of the right-handed series inductor 10 are common parts and are the connection node between the right-handed series inductor 10 and the left-handed parallel inductor 20.

[0087] The direction of the current flowing through the second side 12 and the third side 13 of the right-handed series inductor 10 is the same as the direction of the current flowing through the left-handed parallel inductor 20, which is clockwise in Figure 7. Since the current flowing through the second side 12 and the third side 13 of the right-handed series inductor 10 and the current flowing through the left-handed parallel inductor 20 are in the same direction, the magnetic field created by the second side 12 and the third side 13 of the right-handed series inductor 10 and the magnetic field created by the left-handed parallel inductor 20 are in the same direction, and the coupling coefficient k of the right-handed series inductor 10 and the left-handed parallel inductor 20 is a positive value (k > 0). The right-handed parallel capacitor 40 is connected in parallel to the left-handed parallel inductor 20.

[0088] Next, Figure 8 shows the simulation results of the pass-through characteristic S21 (dB) with respect to the input signal frequency in the CRLH transmission line. The conditions for the CRLH transmission line to obtain the simulation results shown in Figure 8 are as follows. For Application Example 1, a right-handed series inductor 10 and a left-handed parallel inductor 20 were formed on the surface of a SiC substrate with the shape shown in Figure 1, where L1 = 260 μm, L2 = 340 μm, W = 20 μm, and S = 20 μm. For Application Example 2, the shape shown in Figure 7 was formed with L'1 = 260 μm, L'2 = 430 μm, W = 20 μm, and S = 20 μm. In addition, the capacitance values ​​of the left-handed series capacitor 30 and the right-handed parallel capacitor 40 were set to ideal components in the circuit simulator.

[0089] In Figure 8, the horizontal axis represents the frequency of the input signal, and the vertical axis represents the pass-through characteristic S21. The solid line E is the characteristic curve E showing the calculation result in Application Example 1, and the dashed line E2 is the characteristic curve E2 showing the calculation result in Application Example 2. As is clear from Figure 8, the transmission bandwidth of the CRLH line in Application Example 2 is equivalent to the transmission bandwidth of the CRLH line in Application Example 1.

[0090] On the other hand, the area occupied by the right-handed series inductor 10 and the left-handed parallel inductor 20 is S1 (L1 × L2) = 260 × 340 in the CRLH line in Application Example 1, and S2 (L'1 × L'2) = 260 × 430 in the CRLH line in Application Example 2. That is, the area ratio (S1 / S2) is 0.79, and the area occupied by the right-handed series inductor 10 and the left-handed parallel inductor 20 in the CRLH line in Application Example 1 is 20% smaller than the area occupied by the right-handed series inductor 10 and the left-handed parallel inductor 20 in the CRLH line in Application Example 2.

[0091] In short, in Application Example 1, the coupling coefficient k of the right-handed series inductor 10 and the left-handed parallel inductor 20 is a positive value (k > 0), and the axis and direction of rotation of the loop current in the right-handed series inductor 10 are aligned with those of the loop current in the left-handed parallel inductor 20. In other words, the left-handed parallel inductor 20 is placed inside the right-handed series inductor 10 in the same conductive layer, thereby reducing the area occupied by the right-handed series inductor 10 and the left-handed parallel inductor 20 and widening the frequency transmission bandwidth, i.e., making it broadband.

[0092] Application Example 3. An application example when the transmission line according to Embodiment 1 shown in Figure 1 is used as an impedance transformation circuit will be explained with reference to Figure 9. As shown in Figure 9, an impedance transformation circuit is used to match the impedance between the first high-frequency circuit HFC1 and the second high-frequency circuit HFC2. When applied to an impedance transformation circuit, the first terminal 1, the second terminal 2, the third terminal 3, the first inductor section 10, the second inductor section 20, and the connection nodes 10b and 20a between the first inductor section 10 and the second inductor section 20 each function as the input node 1, the first output node 2, the second output node 3, the first inductor 10, the second inductor 20, and the connection nodes 10b and 20a between the first inductor 10 and the second inductor 20, respectively.

[0093] One end of the first inductor 10 is electrically connected to the output node HFC1a of the first high-frequency circuit HFC1, and the other end of the first inductor 10 is electrically connected to the output node HFC2a of the second high-frequency circuit HFC2. In this way, by using the transmission line according to Embodiment 1 shown in Figure 1 as an impedance transformation circuit, an impedance transformation circuit with a wide frequency transmission bandwidth and a small footprint can be obtained.

[0094] Application Example 4. An application example using a CRLH line to which the transmission line according to Embodiment 1 shown in Figure 1 is applied in a distributed amplifier will be explained with reference to Figure 10. As shown in Figure 10, a distributed amplifier has multiple source-grounded transistors Tr arranged in parallel, with the drain electrodes of adjacent transistors Tr electrically connected by drain-side transmission lines D1 to D4, and the gate electrodes of adjacent transistors Tr electrically connected by gate-side transmission lines G1 to G4.

[0095] Each of the gate-side transmission lines G1 to G4 is a CRLH line to which the transmission line according to Embodiment 1 shown in Figure 1 is applied. Each of the gate-side transmission lines G1 to G4 constituting the CRLH line comprises, as shown in Figure 10, a first inductor 10, a second inductor 20, a first capacitor 50 connected in series with the first inductor 10, and a second capacitor 60 connected in series with the second inductor 20.

[0096] The first inductor 10 connects adjacent transistors Tr and functions as a series inductor for applying the gate voltage. The second inductor 20 functions as a left-handed shunt inductor connected via a shunt. The first inductor 10 and the second inductor 20 are the first inductor section 10 and the second inductor section 20 in the transmission line according to Embodiment 1 shown in Figure 1.

[0097] Thus, by making the first inductor section 10 and the second inductor section 20 in the transmission line according to Embodiment 1 shown in Figure 1 into a series inductor 10 and a left-handed shunt inductor 20 in the gate-side transmission lines G1 to G4 that constitute a CRLH line that electrically connects the gate electrodes of adjacent transistors Tr in a distributed amplifier, a wideband transmission characteristic with a wide frequency transmission bandwidth can be achieved, and the occupied area of ​​the series inductor 10 and the left-handed shunt inductor 20 can be reduced.

[0098] In Figure 10, each of the gate-side transmission lines G1 to G4 is a CRLH line to which the transmission line according to Embodiment 1 shown in Figure 1 is applied. However, each of the drain-side transmission lines D1 to D4 may also be a CRLH line to which the transmission line according to Embodiment 1 shown in Figure 1 is applied. Even when each of the drain-side transmission lines D1 to D4 is a CRLH line to which the transmission line according to Embodiment 1 shown in Figure 1 is applied, a wideband transmission characteristic with a wide frequency transmission bandwidth can be achieved, and the area occupied by the CRLH line in each of the drain-side transmission lines D1 to D4 can be reduced.

[0099] Application Example 5. A CRLH transmission line to which the transmission line according to Embodiment 1 shown in Figure 1 is applied is used as a unit cell, and a CRLH transmission line in which two of these unit cells are connected in cascaded order will be described using Figures 11 to 13. The CRLH transmission line according to Application Example 6 comprises two dependently connected CRLH lines A and B, as shown in Figure 11.

[0100] As shown in Figure 11, CRLH lines A and B each comprise left-handed series capacitors 30A and 30B, right-handed series inductors 10A and 10B, left-handed parallel inductors 20A and 20B, and right-handed parallel capacitors 40A and 40B. CRLH line A is designated with the letter A, and CRLH line B is designated with the letter B to distinguish them.

[0101] In the CRLH lines A and B, respectively, the first terminal 1, second terminal 2, third terminal 3, first inductor section 10, second inductor section 20, and connection nodes 10b and 20a between the first inductor section 10 and the second inductor section 20, as shown in Figure 1, function as input nodes 1A and 1B, output nodes 2A and 2B, ground nodes 3A and 3B, first inductors (right-handed series inductors) 10A and 10B, second inductors (left-handed parallel inductors) 20A and 20B, and connection nodes 10Ab, 20Aa, 10Bb, and 20Ba between the first inductors 10A and 10B and the second inductors 20A and 20B.

[0102] The right-handed series inductor 10A and the left-handed parallel inductor 20A in the CRLH transmission line A have the structure shown in Figure 1, as shown in Figure 12. Specifically, the right-handed series inductor 10A is a meander inductor with a counterclockwise U-shape, having a first side 11A, a second side 12A, and a third side 13A.

[0103] The loop current flowing through the right-handed series inductor 10A is counterclockwise, as indicated by the arrow in the diagram. One end 10Aa of the right-handed series inductor 10A is connected in series with the left-handed series capacitor 30A.

[0104] The left-handed parallel inductor 20A has a first annular section 21A, a second annular section 22A, and a lead-out section 23A. The left-handed parallel inductor 20A is a spiral inductor that is wound in a counterclockwise direction. The loop current flowing through the left-handed parallel inductor 20A is counterclockwise, as indicated by the arrows in the figure. The left-handed parallel inductor 20A has a first annular section 21A, a second annular section 22A, and a lead-out section 23A.

[0105] The first annular portion 21A has four sides, from the first side 21Aa to the fourth side 21Ad. The first annular portion 21A is located inside the right-handed series inductor 10A. The second annular portion 22A has four sides, from the first side 22Aa to the fourth side 22Ad. The second annular portion 22A is located inside the first annular portion 21A with a gap S between them. The lead-out portion 23A is L-shaped, having a first side 23Aa and a second side 23Ab. The lead-out portion 23A is located inside the second annular portion 22A.

[0106] The other end (other end) 10Ab of the right-handed series inductor 10A, that is, the other end of the third side 13A of the right-handed series inductor 10A, is connected to one end (one end) 20Aa of the left-handed parallel inductor 20A, that is, one end of the first side 21Aa of the first annular section 21A, forming the output node 2A of the CRLH line A. The output node 2A is electrically connected to the input node 1B of the CRLH line B.

[0107] The other end (other end) 20Ab of the left-handed parallel inductor 20A, that is, the second side 23Ab of the lead-out portion 23A, is connected to the ground node 3A. The coupling coefficient k of the right-handed series inductor 10A and the left-handed parallel inductor 20A is a positive value (k > 0), and the rotation axis and direction of the loop current in the right-handed series inductor 10A are aligned with those of the loop current in the left-handed parallel inductor 20A. The right-handed parallel capacitor 40A is connected in parallel with the left-handed parallel inductor 20A.

[0108] The right-handed series inductor 10B and left-handed parallel inductor 20B in the CRLH transmission line B have a structure similar to that shown in Figure 1, as shown in Figure 12. That is, there is no portion corresponding to the first side 11A of the right-handed series inductor 10A, and the right-handed series inductor 10A and left-handed parallel inductor 20A have an inverted structure in the figure.

[0109] The right-handed series inductor 10B and left-handed parallel inductor 20B in CRLH line B are arranged in parallel in the X-axis direction with respect to the right-handed series inductor 10A and left-handed parallel inductor 20A in CRLH line A. One end 10Ba of the right-handed series inductor 10B is connected to the output node 2A of CRLH line A. The one end 10Ba of the right-handed series inductor 10B and the other end 10Ab of the right-handed series inductor 10A and one end 20Aa of the left-handed parallel inductor 20A in CRLH line A are common parts.

[0110] The right-handed series inductor 10B is a meander inductor with a clockwise L-shape, having a second side 12B and a third side 13B. The current flowing through the right-handed series inductor 10B is clockwise, as indicated by the arrows in the diagram. The second side 12B of the right-handed series inductor 10B is aligned in a straight line with the first side 21Aa of the first annular portion 21A of the left-handed parallel inductor 20A in the CRLH transmission line A. The widths of the second side 12B and the third side 13B of the right-handed series inductor 10B are W.

[0111] The left-handed parallel inductor 20B has a first annular section 21B, a second annular section 22B, and a lead-out section 23B. The left-handed parallel inductor 20B is a spiral inductor. The loop current flowing through the left-handed parallel inductor 20B is clockwise, as indicated by the arrow in the figure.

[0112] The left-handed parallel inductor 20B has a first annular section 21B, a second annular section 22B, and a lead-out section 23B. The first annular section 21B has four sides, from the first side 21Ba to the fourth side 21Bd, arranged clockwise on all four sides.

[0113] The first annular portion 21B is positioned inside the right-handed series inductor 10B, with the third side 21Bc and the fourth side 21Bd facing the second side 12B and the third side 13B of the right-handed series inductor 10B, respectively, with a gap S between them. The second side 21Bb of the first annular portion 21B is positioned facing the third side 13A of the right-handed series inductor 10A in the CRLH line A, with a gap S between them. The width of each side from the first side 21Ba to the fourth side 21Bd of the first annular portion 21B is W.

[0114] The second annular portion 22B has four sides, from the first side 22Ba to the fourth side 22Bd, arranged clockwise along its four edges. The second annular portion 22B is positioned inside the first annular portion 21B with a gap S between them, and each of the first side 22Ba to the fourth side 22Bd is positioned opposite each of the first side 21Ba to the fourth side 21Bd in the first annular portion 21B with a gap S between them. The width of each of the clockwise-arranged first side 22Ba to the fourth side 22Bd in the second annular portion 22B is W.

[0115] The lead-out portion 23B has an L-shape with a first side 23Ba and a second side 23Bb. The lead-out portion 23B is positioned inside the second annular portion 22B, with the first side 23Ba and the second side 23Bb facing each other in the second annular portion 22B with a gap S between them. The other end of the second side 23Bb is electrically connected to a ground node 3B located outside the right-handed series inductor 10B.

[0116] The portion where the second side 23Bb of the lead-out section 23B intersects with the second side 12B of the right-handed series inductor 10B, the third side 21Bc of the first annular section 21B of the left-handed parallel inductor 20B, and the third side 22Bc of the second annular section 22B is intersected by an air bridge between the second side 12B, the third side 21Bc, and the third side 22Bc.

[0117] The other end (other end) 10Bb of the right-handed series inductor 10B, that is, the other end of the third side 13B of the right-handed series inductor 10B, is connected to the one end (one end) 20Ba of the left-handed parallel inductor 20B, that is, the one end of the first side 21Ba of the first annular section 21B, and becomes the output node 2B of the CRLH line B.

[0118] The other end (other end) 20Bb of the left-handed parallel inductor 20B, that is, the second side 23Bb of the lead-out portion 23B, is connected to the ground node 3B. The coupling coefficient k of the right-handed series inductor 10B and the left-handed parallel inductor 20B is a positive value (k > 0), and the rotation axis and direction of the loop current in the right-handed series inductor 10B are aligned with those of the loop current in the left-handed parallel inductor 20B.

[0119] The direction of the loop current flowing through the second side 12B and the third side 13B of the right-handed series inductor 10B is the same as the direction of the loop current flowing through the left-handed parallel inductor 20B, which is clockwise in Figure 12. Since the loop current flowing through the second side 12B and the third side 13B of the right-handed series inductor 10B and the loop current flowing through the left-handed parallel inductor 20B are in the same direction, the magnetic field created by the second side 12B and the third side 13B of the right-handed series inductor 10B and the magnetic field created by the left-handed parallel inductor 20B are in the same direction, and the coupling coefficient k of the right-handed series inductor 10B and the left-handed parallel inductor 20B is a positive value (k > 0).

[0120] The left-handed series capacitor 30B is connected in series with one end 10Ba of the right-handed series inductor 10B and is electrically connected to the output node 2A of the CRLH line A. The right-handed parallel capacitor 40B is connected in parallel with the left-handed parallel inductor 20B.

[0121] Next, Figure 13 shows the simulation results of the pass-through characteristic S21 (dB) with respect to the input signal frequency in a CRLH transmission line with two CRLH lines connected in cascade. The conditions for the CRLH transmission line to obtain the simulation results shown in Figure 13 are as follows: The input load and output load of the CRLH transmission line are both set to 50Ω, and L Ｒ = 0.5 nH, CＲ = 0.5 pF, C Ｌ = 1 pF, L Ｌ The pH was set to 1. Furthermore, the capacitance values ​​of the left-handed series capacitors 30A and 30B, and the right-handed parallel capacitors 40A and 40B, were set as ideal components in the circuit simulator.

[0122] In Figure 13, the horizontal axis represents the frequency of the input signal, and the vertical axis represents the pass-through characteristic S21. The solid line E3 is the characteristic curve E3 showing the calculation result of a CRLH transmission line (Application Example 5) in which two CRLH lines in cascaded configuration are used, with the coupling coefficient k of each CRLH line A and B set to +0.2 (k = 0.2). The dashed line S4 is the characteristic curve S4 showing the calculation result of a CRLH line in cascaded configuration of two CRLH lines in cascaded configuration with the coupling coefficient k of each CRLH line set to 0 (k = 0). The dotted line S5 is the characteristic curve S5 showing the calculation result of a CRLH line in cascaded configuration of two CRLH lines in cascaded configuration with the coupling coefficient k of each CRLH line set to -0.2 (k = -0.2).

[0123] As is clear from Figure 13, the transmission bandwidth of the CRLH transmission line (Application Example 5) in which two CRLH lines are connected in cascaded order in this disclosure is wider than the transmission bandwidth of the CRLH transmission lines in Comparative Examples 4 and 5. Furthermore, the occupied area of ​​each CRLH line A and B in the CRLH transmission line (Application Example 5) is small, and as a result, the occupied area of ​​the CRLH transmission line (Application Example 5) is small.

[0124] In the CRLH transmission line (Application Example 5), in each CRLH line A and B, the right-handed series inductors 10A and 10B were formed using meander inductors, and the left-handed parallel inductors 20A and 20B were formed using spiral inductors. However, by increasing or decreasing the rotation speed of the loop current, the right-handed series inductors 10A and 10B may be formed using spiral inductors, and the left-handed parallel inductors 20A and 20B may be formed using meander inductors.

[0125] Embodiment 2. The transmission line according to Embodiment 2 will be described with reference to Figure 14. While the transmission line according to Embodiment 1 has the first inductor section 10 and the second inductor section 20 formed on the same conductive layer, the transmission line according to Embodiment 2 differs in that the first inductor section 10C and the second inductor section 20C are formed on different conductive layers.

[0126] The transmission line according to Embodiment 2 comprises a first inductor section 10C, a second inductor section 20C, and a connector 50. The first inductor section 10C and the second inductor section 20 are formed on a multilayer substrate of an integrated circuit having an upper conductive layer formed in the upper X-Y plane PL1 and a lower conductive layer formed in the lower X-Y plane PL2 on the surface of an insulating substrate.

[0127] The first inductor portion 10C is formed in either the upper or lower conductive layer. Figure 14 shows the case where it is formed in the upper conductive layer. The second inductor portion 20C is formed in the other conductive layer. Figure 14 shows the case where it is formed in the lower conductive layer.

[0128] The connector 50 is a through-hole or the like that electrically connects the other end 10Cb of the first inductor section 10 to one end 20Ca of the second inductor section 20C. The connector 50 may also be a cylindrical conductor made of a conductive material. One end 10Ca of the first inductor section 10C is electrically connected to the first terminal 1, and the other end 10b is electrically connected to the second terminal 2. The other end 20Cb of the second inductor section 20C is connected to the third terminal 3.

[0129] The first inductor section 10C has the same shape as the first inductor section 10 in the transmission line according to Embodiment 1, and is a U-shaped meander inductor section having a first side 11C to a third side 13C with a width W in a counterclockwise direction. A counterclockwise loop-shaped current flows through the first inductor section 10C.

[0130] The second inductor section 20C has the same shape as the second inductor section 20 in the transmission line according to Embodiment 1, and is a spiral inductor section with a first annular section 21C, a second annular section 22C, and a lead-out section 23C. A counterclockwise loop-shaped current flows through the second inductor section 20C as well.

[0131] The first annular portion 21C has four sides, from the first side 21Ca to the fourth side 21Cd, arranged counterclockwise along its four sides, with a width of W. The second annular portion 22C has four sides, from the first side 22Ca to the fourth side 22Cd, arranged counterclockwise along its four sides, with a width of W. The pull-out portion 23C is L-shaped, with the first side 23Ca and the second side 23Cb arranged counterclockwise.

[0132] The rotation axis and direction of the loop current in the first inductor section 10C are aligned with those of the loop current in the second inductor section 20C, and the coupling coefficient k of the first inductor section 10C and the second inductor section 20C is a positive value (k > 0).

[0133] The transmission line according to Embodiment 2 comprises a first inductor section 10C and a second inductor section 20C, and is arranged such that the coupling coefficient k of the first inductor section 10C and the second inductor section 20C is a positive value (k > 0), thereby enabling higher bandwidth in the transmission line. The first inductor section 10C and the second inductor section 20C are placed on different conductive layers, and the rotation axis and direction of the loop current in the first inductor section 10C and the rotation axis and direction of the loop current in the second inductor section 20C are aligned, thereby reducing the area occupied by the transmission line.

[0134] Furthermore, since the first inductor section 10C and the second inductor section 20C are arranged on different conductive layers, the shapes of the first inductor section 10C and the second inductor section 20C can be freely set. In other words, the in-plane dimensions of the first inductor section 10C can be freely changed independently of the in-plane dimensions of the second inductor section 20C, increasing the degree of design freedom.

[0135] In short, the first inductor section 10C is not limited to a meander inductor section and the second inductor section 20C to a spiral inductor section. By aligning the rotation axis and direction of the loop-shaped current, and generating electromagnetic field coupling between the first inductor section 10C and the second inductor section 20C, that is, by satisfying the condition that the coupling coefficient k between the first inductor section 10C and the second inductor section 20C is a positive value (k > 0), various shapes can be achieved.

[0136] Furthermore, the transmission line according to Embodiment 2 can be applied to the transmission line for transmitting high-frequency signals (currents) as described in Embodiment 1, the CRLH line (Application Example 1), the impedance transformation circuit (Application Example 3), the distributed amplifier using the CRLH line (Application Example 4), and the CRLH transmission line (Application Example 5) formed by connecting two CRLH lines in cascaded order.

[0137] For example, when applied to a CRLH line (Application Example 1), the first terminal 1, second terminal 2, third terminal 3, first inductor section 10C, second inductor section 20C, and connection nodes 10Cb and 20Ca between the first inductor section 10C and the second inductor section 20C, as shown in Figure 14, function as input node 1, output node 2, ground node 3, first inductor (right-handed series inductor) 10C, second inductor (left-handed parallel inductor) 20C, and connection nodes 10Cb and 20Ca between the right-handed series inductor 10C and the left-handed parallel inductor 20C, respectively.

[0138] A left-handed series capacitor 30 is connected in series with the right-handed series inductor 10C between one end 10Ca of the right-handed series inductor 10C and the input node 1. A right-handed parallel capacitor 40 is connected in parallel with the left-handed parallel inductor 20C between the output node 2 and the ground node 3.

[0139] A CRLH transmission line can be realized using the left-handed series capacitor 30, the right-handed series inductor 10C, the left-handed parallel inductor 20C, and the right-handed parallel capacitor 40, applying the first inductor 10C and the second inductor 20C shown in Embodiment 2. Even with a CRLH transmission line configured in this way, the transmission bandwidth can be widened and the area occupied by the CRLH transmission line in the plane can be reduced.

[0140] Embodiment 3. The transmission line according to Embodiment 3 will be described with reference to Figure 15. In the transmission line according to Embodiment 1, the first inductor section 10 and the second inductor section 20 are formed on the same conductive layer on the surface of the insulating substrate. In contrast, in the transmission line according to Embodiment 3, the first inductor section 10D is formed from a conductive layer which is a metal layer on the surface of the printed circuit board PS, and the second inductor section 20D is composed of a chip inductor CI mounted on the surface of the printed circuit board PS.

[0141] The transmission line according to Embodiment 3 comprises a first inductor section 10D and a second inductor section 20D. The first inductor section 10D is a U-shaped meander inductor section formed on a conductive layer on the surface of the printed circuit board PS, having the same shape as the first inductor section 10 in the inductor according to Embodiment 1, and having a first side 11D to a third side 13D in a counterclockwise direction. The first inductor section 10D is a plated wiring formed on the surface of the printed circuit board PS.

[0142] A counterclockwise loop current flows through the first inductor section 10D. The center of the region enclosed by the first side 11D, the second side 12D, and the third side 13D becomes the axis of rotation of the loop current flowing through the first inductor section 10D. One end 10Da of the first inductor section 10D is electrically connected to the first terminal 1C, and the other end 10Db is electrically connected to the second terminal 2C.

[0143] The second inductor section 20D is composed of a chip inductor CI. The chip inductor CI is a laminated inductor in which a coil pattern is formed in a stacked manner inside a non-conductive body. It has a pair of electrodes on a pair of opposing end faces of the body. The coil pattern formed inside the body is a wound type (spiral shape) in which the winding surface is parallel to the upper and lower surfaces of the body.

[0144] In the chip inductor CI, the coil is the second inductor portion 20D, one electrode of a pair of electrodes is one end 20Da of the second inductor portion 20D, and the other electrode of the pair of electrodes is the other end 20Db of the second inductor portion 20D. The chip inductor CI is mounted on the surface of the printed circuit board PS in the region enclosed by the first side 11D, the second side 12D, and the third side 13D of the first inductor portion 10D. The chip inductor CI is mounted on the surface of the printed circuit board PS by soldering.

[0145] The chip inductor CI is mounted with the coil pattern winding surface parallel to the surface of the printed circuit board PS, and the coil winding direction is counterclockwise. The rotation axis and rotation direction of the coil in the chip inductor CI, that is, the second inductor section 20D, are the same as those of the first inductor section 10D, and the chip inductor CI is mounted on the surface of the printed circuit board PS.

[0146] One electrode of the chip inductor CI is electrically and mechanically connected by solder to the other end 10Db of the first inductor portion 10D, and the other electrode is electrically and mechanically connected by solder to a third terminal 3C formed on the surface of the printed circuit board PS, thereby mounting the inductor. A counterclockwise loop current flows through the second inductor portion 20D. The center of the coil pattern forming the second inductor portion 20D becomes the axis of rotation of the loop current flowing through the second inductor portion 20D.

[0147] In short, the rotation axis and direction of the loop current in the first inductor section 10D are aligned with those of the loop current in the second inductor section 20D, and the coupling coefficient k of the first inductor section 10D and the second inductor section 20D is a positive value (k > 0).

[0148] The transmission line according to Embodiment 3 comprises a first inductor section 10D formed on the surface of a printed circuit board PS and a second inductor section 20D composed of a chip inductor CI. The coupling coefficient k of the first inductor section 10D and the second inductor section 20D is set to a positive value (k > 0), thereby enabling higher bandwidth in the transmission line.

[0149] Since the chip inductor CI constituting the second inductor section 20D is mounted inside the first inductor section 10D, and the rotation axis and direction of the loop current in the first inductor section 10 are aligned with those of the second inductor section 20, the area occupied by the transmission line can be reduced.

[0150] In this example, the chip inductor CI constituting the second inductor section 20D is a wound-type (spiral-shaped) coil chip inductor CI, but the second inductor section 20D may also be a film-type chip inductor CI with a planar spiral conductive pattern.

[0151] Furthermore, the transmission line according to Embodiment 3 can be applied to the transmission line for transmitting high-frequency signals (currents) as described in Embodiment 1, the CRLH line (Application Example 1), the impedance transformation circuit (Application Example 3), the distributed amplifier using the CRLH line (Application Example 4), and the CRLH transmission line (Application Example 5) formed by connecting two CRLH lines in cascaded order.

[0152] For example, when applied to a CRLH transmission line (Application Example 1), the first terminal 1C, second terminal 2C, third terminal 3C, first inductor section 10D, second inductor section 20D, and connection nodes 10Db and 20Da between the first inductor section 10D and the second inductor section 20D, as shown in Figure 15, function as input node 1C, output node 2C, ground node 3C, first inductor (right-handed series inductor) 10D, second inductor (left-handed parallel inductor) 20D, and connection nodes 10Db and 20Da between the right-handed series inductor 10D and the left-handed parallel inductor 20D, respectively.

[0153] A left-handed series capacitor 30 is connected in series with the right-handed series inductor 10C between one end 10Da of the right-handed series inductor 10D and the input node 1. A right-handed parallel capacitor 40 is connected in parallel with the left-handed parallel inductor 20D between the output node 2C and the ground node 3C.

[0154] A CRLH transmission line can be realized using the left-handed series capacitor 30, the right-handed series inductor 10D, the left-handed parallel inductor 20D, and the right-handed parallel capacitor 40, applying the first inductor 10D and the second inductor 20D shown in Embodiment 3. Even with a CRLH transmission line configured in this way, the transmission bandwidth can be widened and the area occupied by the CRLH transmission line in the plane can be reduced.

[0155] Furthermore, it is possible to freely combine the embodiments, modify any component of each embodiment, or omit any component of each embodiment.

[0156] The transmission lines relating to this disclosure are applicable to transmission lines that transmit high-frequency signals (currents) implemented in high-frequency integrated circuits, right-handed / left-handed composite transmission lines, and choke coils for bias application in high-frequency amplifiers, impedance transformation circuits, and filter circuits.

[0157] 1, 1A, 1B, 1C First terminal, input node; 2, 2A, 2B, 2C Second terminal, output node; 3, 3A, 3B, 3C Third terminal, ground node; 10, 10A, 10B, 10C First inductor section, first inductor, right-handed series inductor; 20, 20A, 20B, 20C Second inductor section, second inductor, left-handed parallel inductor; 30, 30A, 30B Left-handed series capacitor; 40, 40A, 40B Right-handed parallel capacitor; 50 Connector.

Claims

1. A transmission line comprising: a first inductor section having one end connected to a first terminal and the other end connected to a second terminal; and a second inductor section having one end connected to the other end of the first inductor section and the other end connected to a third terminal, wherein the coupling coefficient between the first inductor section and the second inductor section is a positive value.

2. A transmission line comprising: a first inductor having one end connected to an input node and the other end connected to a first output node; and a second inductor having one end connected to the other end of the first inductor and the other end connected to a second output node, wherein the coupling coefficient between the first inductor and the second inductor is a positive value.

3. The transmission line according to claim 2, wherein a loop current due to a high-frequency signal input to the input node flows through the first inductor from the input node to the first output node, a loop current due to a high-frequency signal branched from the first inductor flows through the second inductor to the second output node, and the axis and direction of rotation of the loop current in the first inductor and the axis and direction of rotation of the loop current in the second inductor are aligned.

4. The transmission line according to claim 2, wherein a loop current due to a high-frequency signal input to the input node flows through the first inductor from the input node to the first output node, a loop current due to a high-frequency signal branched from the first inductor to the second output node flows through the second inductor, and the second inductor is located inside the first inductor in the same conductive layer on which the first inductor is formed.

5. The transmission line according to claim 2, wherein a loop current due to a high-frequency signal input to the input node flows through the first inductor from the input node to the first output node, a loop current due to a high-frequency signal branched from the first inductor and directed to the second output node flows through the second inductor, and the first inductor and the second inductor are arranged on different conductive layers such that the axis and direction of rotation of the loop current in the first inductor and the axis and direction of rotation of the loop current in the second inductor are aligned.

6. A transmission line according to claim 2, wherein a loop current flows through the first inductor from the input node to the first output node due to a high-frequency signal input to the input node, a loop current flows through the second inductor branched from the first inductor to the second output node due to a high-frequency signal, the first inductor is formed by a conductive layer on the surface of a printed circuit board, the second inductor is composed of a chip inductor mounted on the surface of the printed circuit board, and the first inductor and the second inductor are arranged such that the axis and direction of rotation of the loop current in the first inductor and the axis and direction of rotation of the loop current in the second inductor are aligned.

7. A right-handed / left-handed composite transmission line comprising: a right-handed series inductor; a left-handed parallel inductor, one end of which is connected to the other end of the right-handed series inductor and the other end of which is connected to a ground node, and whose coupling coefficient with the right-handed series inductor is a positive value; a left-handed series capacitor, connected in series with the right-handed series inductor between the input node and the output node, and which together with the left-handed parallel inductor constitutes a left-handed transmission line; and a right-handed parallel capacitor, connected in parallel with the left-handed parallel inductor, and which together with the right-handed series inductor constitutes a right-handed transmission line.

8. The right-handed / left-handed composite transmission line according to claim 7, wherein in the right-handed series inductor, a loop current flows from one end to the other due to a signal input to the one end, in the left-handed parallel inductor, a loop current flows from one end to the other due to a signal input to the one end, branched from the other end of the right-handed series inductor, and the axis of rotation and direction of rotation of the loop current in the right-handed series inductor are aligned with the axis of rotation and direction of rotation of the loop current in the left-handed parallel inductor.

9. The right-handed / left-handed composite transmission line according to claim 7, wherein in the right-handed series inductor, a loop current flows from one end to the other due to a signal input to the one end, in the left-handed parallel inductor, a loop current flows from one end to the other due to a signal input to the one end, branched from the other end of the right-handed series inductor, and the left-handed parallel inductor is arranged inside the right-handed series inductor in the same conductive layer on which the right-handed series inductor is formed.

10. The right-handed / left-handed composite transmission line according to claim 7, wherein in the right-handed series inductor, a loop current flows from one end to the other due to a signal input to the one end, and in the left-handed parallel inductor, a loop current flows from one end to the other due to a signal input to the one end, branched from the other end of the right-handed series inductor, and the right-handed series inductor and the left-handed parallel inductor are arranged in different conductive layers such that the axis of rotation and direction of rotation of the loop current in the right-handed series inductor and the axis of rotation and direction of rotation of the loop current in the left-handed parallel inductor are aligned.

11. The right-handed / left-handed composite transmission line according to claim 7, wherein in the right-handed series inductor, a loop current flows from one end to the other due to a signal input to the one end, in the left-handed parallel inductor, a loop current flows from one end to the other due to a signal input to the one end, branched from the other end of the right-handed series inductor, the right-handed series inductor is formed by a conductive layer on the surface of a printed circuit board, the left-handed parallel inductor is composed of a chip inductor mounted on the surface of the printed circuit board, and the right-handed series inductor and the left-handed parallel inductor are arranged so that the axis of rotation and direction of rotation of the loop current in the right-handed series inductor and the axis of rotation and direction of rotation of the loop current in the left-handed parallel inductor are aligned.

12. A right-handed / left-handed composite transmission line comprising: a right-handed / left-handed composite line A according to any one of claims 7 to 11; and a right-handed / left-handed composite line B according to any one of claims 7 to 11, which is dependently connected to the right-handed / left-handed composite line A.

13. The right-handed / left-handed composite transmission line according to claim 12, wherein in the right-handed / left-handed composite transmission line A, one electrode of the left-handed series capacitor is connected to the input node, one end of the right-handed series inductor is connected to the other electrode of the left-handed series capacitor, and the other end of the right-handed series inductor is connected to the output node; in the right-handed / left-handed composite transmission line B, one end of the right-handed series inductor is connected to the input node, the other end of the right-handed series inductor is connected to one electrode of the left-handed series capacitor, and the other electrode of the left-handed series capacitor is connected to the output node; and the input node to which one end of the right-handed series inductor is connected in the right-handed / left-handed composite transmission line B is connected is connected to the output node to which the other end of the right-handed series inductor in the right-handed / left-handed composite transmission line A is connected.

14. An impedance transformation circuit connected between a first high-frequency circuit and a second high-frequency circuit for impedance matching between the first high-frequency circuit and the second high-frequency circuit, comprising: a first inductor having one end connected to the output terminal of the first high-frequency circuit and the other end connected to the input terminal of the second high-frequency circuit; and a second inductor having one end connected to the other end of the first inductor and having a positive coupling coefficient with the first inductor.

15. A distributed amplifier in which multiple source-grounded transistors are arranged in parallel, the drain electrodes of adjacent transistors are electrically connected by drain-side transmission lines, and the gate electrodes of adjacent transistors are electrically connected by gate-side transmission lines, wherein each of the gate-side transmission lines that electrically connect the gate electrodes of adjacent transistors in the gate-side transmission lines is configured with a right-handed / left-handed composite transmission line as described in any one of claims 7 to 11.

16. A distributed amplifier in which multiple source-grounded transistors are arranged in parallel, the drain electrodes of adjacent transistors are electrically connected by drain-side transmission lines, and the gate electrodes of adjacent transistors are electrically connected by gate-side transmission lines, wherein each of the drain-side transmission lines that electrically connect the drain electrodes of adjacent transistors in the drain-side transmission lines is configured by a right-handed / left-handed composite transmission line as described in any one of claims 7 to 11.

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