High-frequency circuits

Abstract

A high-frequency circuit (1) comprises: a transmission line (10); a first switching circuit (11) that is connected to one end of the transmission line (10) and that switches a connection between the one end of the transmission line (10) and a plurality of first circuits (20); and a second switching circuit (12) that is connected to the other end of the transmission line (10) and that switches a connection between the other end of the transmission line (10) and a plurality of second circuits (30). f / fm0=2n / m in a case where fm0 is the switching frequency of the first switching circuit (11) and the second switching circuit (12), f is the frequency of a signal propagated on the transmission line (10), λm0 is a wavelength with respect to the switching frequency, m is an integer of 1 or more, n is an integer of 0 or more, and the length of the transmission line (10) is mλm0 / 4.

Description

[Technical Field]

[0001] The present invention relates to a high-frequency circuit. [Background technology]

[0002] Patent Document 1 describes a line-switching phase shifter for switching circuits connected to a transmission line. Non-Patent Document 1 describes a line-switching gyrator for switching circuits connected to a transmission line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-13071 [Non-patent literature]

[0004] [Non-Patent Document 1] RFIC2018,“Fully-Integrated Non-Magnetic 180nm SOI Circulator with >1W P1dB, >+50dBm IIP3 and High Isolation across 1.85 VSWR” Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the line-switching type phase shifter described in Patent Document 1 and the line-switching type gyrator described in Non-Patent Document 1 are applied to the microwave band, the transmission line (λ / 4 line) becomes large. Also, even when the transmission line is configured by approximating it with a lumped constant circuit using inductors, capacitors, etc., the number of elements increases, resulting in a large transmission line.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a high-frequency circuit that allows the size of a transmission line to be reduced. [Means for solving the problem]

[0007] A high-frequency circuit according to one aspect of the present invention includes a first transmission line, a first switching circuit connected to one end of the first transmission line and switching a connection between the one end of the first transmission line and a plurality of first circuits, and a second switching circuit connected to the other end of the first transmission line and switching a connection between the other end of the first transmission line and a plurality of second circuits, m0 is the switching frequency of the first switching circuit and the second switching circuit, f is the frequency of the signal propagating through the first transmission line, and λ m0 is the wavelength for the switching frequency, m is an integer equal to or greater than 1, n is an integer equal to or greater than 0, and the length of the first transmission line is mλ m0 / 4, f / f m0 =2n / m.

[0008] A high-frequency circuit according to one aspect of the present invention includes a plurality of first transmission lines, a first switching circuit connected to one end of each of the plurality of first transmission lines and switching a connection between each of the one ends of the plurality of first transmission lines and a first circuit, and a second switching circuit connected to the other end of each of the plurality of first transmission lines and switching a connection between each of the other ends of the plurality of first transmission lines and a second circuit, m0 is the switching frequency of the first switching circuit and the second switching circuit, f is the frequency of the signal propagating through the first transmission line, and λ m0 is the wavelength for the switching frequency, m is an integer equal to or greater than 1, n is an integer equal to or greater than 0, and the length of the first transmission line is mλ m0 / 4, f / f m0 =2n / m. [Effects of the Invention]

[0009] According to the present invention, the transmission line can be made smaller. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a configuration diagram showing an example of a high-frequency circuit according to an embodiment. [Figure 2]FIG. 2 is a configuration diagram showing another example of a high-frequency circuit according to an embodiment. [Figure 3] FIG. 3 is a configuration diagram showing another example of a high-frequency circuit according to an embodiment. [Figure 4] FIG. 4 is a configuration diagram showing an example of a circulator to which the high-frequency circuit according to the embodiment is applied. [Figure 5] FIG. 5 is a diagram for explaining the input impedance of a transmission line. [Figure 6] FIG. 6 is a diagram showing frequency characteristics of input impedance of a transmission line. [Figure 7A] FIG. 7A is a diagram showing a drive signal of a switching circuit at a first timing. [Figure 7B] FIG. 7B is a diagram showing the switching state of the switching circuit at the first timing. [Figure 8A] FIG. 8A is a diagram showing a drive signal of the switching circuit at the second timing. [Figure 8B] FIG. 8B is a diagram showing the switching state of the switching circuit at the second timing. [Figure 9A] FIG. 9A is a diagram showing a drive signal of the switching circuit at the third timing. [Figure 9B] FIG. 9B is a diagram showing the switching state of the switching circuit at the third timing. [Figure 10A] FIG. 10A is a diagram showing a drive signal of the switching circuit at a fourth timing. [Figure 10B] FIG. 10B is a diagram showing the switching state of the switching circuit at the fourth timing. [Figure 11] FIG. 11 is a configuration diagram showing an example of a ladder-type transmission line configured with an L-type circuit. [Figure 12] FIG. 12 is a diagram showing the isolation characteristics of a circulator to which a ladder-type transmission line configured with an L-type circuit is applied. [Figure 13] FIG. 13 is a configuration diagram showing an example of a ladder-type transmission line configured with a π-Lattice type circuit. [Figure 14] FIG. 14 is a Smith chart showing the impedance characteristics of a ladder-type transmission line configured with a π-Lattice circuit. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangements, and connection configurations shown in the following embodiments are merely examples and are not intended to limit the present invention. Among the components in the following embodiments, components not recited in the independent claims will be described as optional components. Furthermore, the sizes and size ratios of the components shown in the drawings are not necessarily strict. Furthermore, in each figure, substantially identical components are assigned the same reference numerals, and redundant descriptions may be omitted or simplified. Furthermore, in the following embodiments, "connected" includes not only direct connection but also electrical connection via other elements (e.g., capacitors, inductors, or semiconductor elements such as diodes or transistors).

[0012] (Embodiment) The embodiment will be described with reference to FIGS. 1 to 14. FIG.

[0013] FIG. 1 is a configuration diagram showing an example of a high-frequency circuit 1 according to an embodiment.

[0014] The high-frequency circuit 1 is a circuit for switching a path for transmitting a high-frequency signal (Radio Frequency (RF) signal), and includes a transmission line 10 and switching circuits 11 and 12 connected to both ends of the transmission line 10.

[0015] The transmission line 10 is an example of a first transmission line. The transmission line 10 may be configured with lumped elements (passive elements) using inductors and capacitors. The transmission line 10 may also be configured with a stripline-based line in which a conductor is formed on a dielectric, such as a microstrip line, a stripline, a coplanar guideline, or a coplanar guideline with a GND. The high-frequency circuit 1 may include one or more transmission lines 10, and FIG. 1 shows an example in which a plurality of transmission lines 10 are included.

[0016] The switching circuit 11 is an example of a first switching circuit. The switching circuit 11 is connected to one end of the transmission line 10 and switches the connection between the one end of the transmission line 10 and the first circuit 20. The first circuit 20 may be configured with a second transmission line, may be configured with passive elements, or may be configured with a delay circuit configured with passive elements. The second transmission line is referred to as a "second" transmission line to distinguish it from the transmission line 10, which is an example of the first transmission line.

[0017] The switching circuit 12 is an example of a second switching circuit. The switching circuit 12 is connected to the other end of the transmission line 10 and switches the connection between the other end of the transmission line 10 and the second circuit 30. The second circuit 30 may be configured with a second transmission line, passive elements, or a delay circuit configured with passive elements.

[0018] 1 , the switching circuit 11 may switch the connection between one end of each of the multiple transmission lines 10 and multiple first circuits 20, and the switching circuit 12 may switch the connection between the other end of each of the multiple transmission lines 10 and multiple second circuits 30. When the high-frequency circuit 1 includes only one transmission line 10, the switching circuit 11 switches the connection between one end of the transmission line 10 and the multiple first circuits 20, and the switching circuit 12 switches the connection between the other end of the transmission line 10 and the multiple second circuits 30. When there is only one first circuit 10 and one second circuit 30, the high-frequency circuit 1 includes multiple transmission lines 10, the switching circuit 11 switches the connection between one end of each of the multiple transmission lines 10 and the first circuit 20, and the switching circuit 12 switches the connection between the other end of each of the multiple transmission lines 10 and the second circuit 30.

[0019] The switching circuits 11 and 12 may each be configured with a three-terminal semiconductor element (semiconductor switch) whose conduction and non-conduction are controlled by a control signal. For example, the switching circuits 11 and 12 may each be configured with a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The switching circuits 11 and 12 may each be configured with a mechanical switch whose conduction and non-conduction are controlled by a control signal. The conduction and non-conduction of the switches in the switching circuits 11 and 12 are switched according to the switching frequency of the switching circuits 11 and 12 (frequency LO, described below).

[0020] When there are multiple first circuits 20, one end of the transmission line 10 may be exclusively connected to one of the multiple first circuits 20 by the switching circuit 11. Specifically, when the connection between one end of the transmission line 10 and the multiple first circuits 20 is switched in order by the switching circuit 11, the one end of the transmission line 10 is connected to only one of the multiple first circuits 20, and does not have to be connected to two or more first circuits 20 at the same time.

[0021] When there are multiple second circuits 30, the other end of the transmission line 10 may be connected exclusively to one of the multiple second circuits 30 by the switching circuit 12. Specifically, when the connection between the other end of the transmission line 10 and the multiple second circuits 30 is switched in order by the switching circuit 12, the other end of the transmission line 10 is connected to only one of the multiple second circuits 30, and does not have to be connected to two or more second circuits 30 at the same time.

[0022] When the high-frequency circuit 1 includes a plurality of transmission lines 10, the first circuit 20 may be connected exclusively to one end of one of the plurality of transmission lines 10 by the switching circuit 11. Specifically, when the connection between one end of the plurality of transmission lines 10 and the first circuit 20 is switched in order by the switching circuit 11, the first circuit 20 is connected to only one of the plurality of transmission lines 10, and does not necessarily have to be connected to two or more transmission lines 10 at the same time.

[0023] Furthermore, when the high-frequency circuit 1 includes a plurality of transmission lines 10, the second circuit 30 may be connected exclusively to the other end of one of the plurality of transmission lines 10 by the switching circuit 12. Specifically, when the connections between the other ends of the plurality of transmission lines 10 and the second circuit 30 are switched in order by the switching circuit 12, the second circuit 30 is connected to only one of the plurality of transmission lines 10, and does not need to be connected to two or more transmission lines 10 at the same time.

[0024] 2 and 3 are configuration diagrams showing another example of the high-frequency circuit 1 according to the embodiment. As shown in FIG. 2, a plurality of first circuits 20 and a plurality of second circuits 30 may be connected to one transmission line 10 by switching circuits 11 and 12. Although two first circuits 20 and two second circuits 30 are shown in FIG. 2, three or more first circuits 20 and three or more second circuits 30 may be connected to one transmission line 10 by switching circuits 11 and 12. Furthermore, as shown in FIG. 3, one first circuit 20 and one second circuit 30 may be connected to multiple transmission lines 10 by switching circuits 11 and 12. Although two transmission lines 10 are shown in FIG. 3, one first circuit 20 and one second circuit 30 may be connected to three or more transmission lines 10 by switching circuits 11 and 12.

[0025] λ m0 is the wavelength for the switching frequency of the switching circuits 11 and 12, and m is an integer equal to or greater than 1, the length of the transmission line 10 is mλ m0 / 4.

[0026] Such a high-frequency circuit 1 can be applied to a gyrator that uses a mixer that uses a switch, and the high-frequency circuit 1 that is a gyrator can be applied to a circulator. A circulator to which the high-frequency circuit 1 is applied will be described below.

[0027] FIG. 4 is a configuration diagram showing an example of a circulator to which the high-frequency circuit 1 according to the embodiment is applied.

[0028] For example, the high-frequency circuit 1 includes transmission lines 10a and 10b, a switching circuit 11 connected to one end of the transmission lines 10a and 10b and switching the connection between the one end of the transmission lines 10a and 10b and first circuits 20a and 20b, and a switching circuit 12 connected to the other end of the transmission lines 10a and 10b and switching the connection between the other end of the transmission lines 10a and 10b and second circuits 30a and 30b. Specifically, the switching circuit 11 switches the connection between one end of the transmission line 10a and the first circuits 20a and 20b, and switches the connection between one end of the transmission line 10b and the first circuits 20a and 20b. The switching circuit 12 switches the connection between the other end of the transmission line 10a and the second circuits 30a and 30b, and switches the connection between the other end of the transmission line 10b and the second circuits 30a and 30b.

[0029] For example, the switching circuit 11 includes four switches whose conduction and non-conduction are controlled by a drive signal of a switching frequency LO. One end of the transmission line 10a is connected to the first circuit 20a via a switch controlled by a drive signal LO1+ of frequency LO from a local oscillator. One end of the transmission line 10a is connected to the first circuit 20b via a switch controlled by a drive signal LO1- of frequency LO from the local oscillator. One end of the transmission line 10b is connected to the first circuit 20a via a switch controlled by a drive signal LO1- of frequency LO from the local oscillator. One end of the transmission line 10b is connected to the first circuit 20b via a switch controlled by a drive signal LO1+ of frequency LO from the local oscillator.

[0030] For example, the switching circuit 12 includes four switches whose conduction and non-conduction are controlled by a drive signal of a switching frequency LO. The other end of the transmission line 10a is connected to a second circuit 30a via a switch controlled by a drive signal LO2+ of a frequency LO from a local oscillator. The other end of the transmission line 10a is connected to a second circuit 30b via a switch controlled by a drive signal LO2- of a frequency LO from the local oscillator. The other end of the transmission line 10b is connected to the second circuit 30a via a switch controlled by a drive signal LO2- of a frequency LO from the local oscillator. The other end of the transmission line 10b is connected to the second circuit 30b via a switch controlled by a drive signal LO2+ of a frequency LO from the local oscillator.

[0031] Switching circuits 11 and 12 operate as Gilbert cell mixers, and high-frequency circuit 1 operates as a gyrator. By using high-frequency circuit 1 operating as a gyrator, it is possible to realize a circulator that transmits an RF signal input to transmission terminal 51 to antenna terminal 52 with low loss, transmits an RF signal input to antenna terminal 52 to reception terminal 53 with low loss, and improves isolation between transmission terminal 51 and reception terminal 53.

[0032] The transmitting terminal 51 and the antenna terminal 52 are connected via third circuits 40a and 40b. The third circuits 40a and 40b are, for example, transmission lines (second transmission lines). The transmitting terminal 51 and the high-frequency circuit 1 are connected via first circuits 20a and 20b. The first circuits 20a and 20b are, for example, transmission lines (second transmission lines). The antenna terminal 52, the receiving terminal 53, and the high-frequency circuit 1 are connected via second circuits 30a and 30b. The second circuits 30a and 30b are, for example, transmission lines (second transmission lines).

[0033] In the high frequency circuit 1, a switching circuit 11, which is a Gilbert cell mixer connected to one end of the transmission lines 10a and 10b, is driven by a driving signal LO1- whose phase is inverted by 180° from a driving signal LO1+ of frequency LO, and the frequency f RF Base Band (BB) frequency f BB =f RF ±LO and the transmission lines 10a and 10b (λ m0 The high-frequency circuit 1, which is a gyrator, drives the switching circuit 12, which is a Gilbert cell mixer connected to the other end of the transmission lines 10a and 10b, with the driving signals LO2+ and LO2-, which have a frequency LO that is 90° phase delayed from the driving signals LO1+ and LO1-, to generate a BB signal at a frequency f BB The frequency f RF and a non-reciprocal relationship is created by generating a 90° phase lead and a 90° phase delay in the RF signal propagating clockwise and the RF signal propagating counterclockwise in the circulator shown in Figure 4. The high-frequency circuit 1 has the S parameters of the following equation 1. m0 are the wavelengths of the drive signals LO1+, LO1−, LO2+ and LO2−, and the wavelength λ is the wavelength of the RF signal.

[0034]

number

[0035] The high-frequency circuit 1 includes two transmission lines 10a and 10b (λ m0 / 4 lines) is switched at the frequency LO.

[0036] When such a high-frequency circuit 1 is applied to the microwave band, the transmission lines 10a and 10b (λ m0 Specifically, the λ / 4 line used in the high frequency circuit 1 may become large. m0The BB signal, which has a lower frequency than the RF signal, propagates through the λ / 4 line. For example, by setting the LO frequency to 1 / 3 of the RF signal frequency, the BB signal will have a frequency of 2 / 3 and 4 / 3 of the RF signal frequency, and the wavelength λ m0 is three times the wavelength of the RF signal, so λ m0 However, according to the present invention, as will be explained below, it is possible to reduce the size of the transmission lines 10a and 10b.

[0037] 5 is a diagram for explaining the input impedance of the transmission lines 10a and 10b. m0 The input impedance of the transmission lines 10a and 10b is explained below. m0 is the characteristic impedance of the transmission lines 10a and 10b, Z L is the impedance of the transmission lines (first circuits 20a and 20b and second circuits 30a and 30b) connected to the transmission lines 10a and 10b, C0 is the speed of light, f m0 is the switching frequency of the switching circuits 11 and 12, λ m0 f m0 where f is the frequency of the signal propagating through the transmission lines 10a and 10b, λ is the wavelength for f, and ε r is the relative dielectric constant of the transmission lines 10a and 10b, m is an integer equal to or greater than 1, and n is an integer equal to or greater than 0. In this case, λ m0 =C0 / (f m0 ×√ε r ), λ=C0 / (f×√ε r ) holds. In the following description, when there is no need to distinguish between the transmission lines 10a and 10b, the transmission lines 10a and 10b will also be referred to as transmission lines 10. Similarly, when there is no need to distinguish between the first circuits 20a and 20b, the first circuits 20a and 20b will also be referred to as first circuits 20. Similarly, when there is no need to distinguish between the second circuits 30a and 30b, the second circuits 30a and 30b will also be referred to as second circuits 30. Similarly, when there is no need to distinguish between the third circuits 40a and 40b, the third circuits 40a and 40b will also be referred to as third circuits 40.

[0038] The following equation 2 is the input impedance Z of the transmission line 10. in The analytical formula for is shown below.

[0039]

number

[0040] From equation 2, the length is mλ m0 In the transmission line 10 of / 4, when βx'=nπ, Z in =Z L That is, f / f m0 = 2n / m, Z in =Z L For example, if the frequency of the RF signal is f RF 900MHz, the switching frequency LO of the switching circuits 11 and 12 (i.e., frequency f m0 ) is 300 MHz, the frequency f of the BB signal propagating through the transmission line 10 BB (i.e., frequency f) is 600MHz (900MHz - 300MHz) and 1200MHz (900MHz + 300MHz), and f / f m0 =f BB / LO=600MHz / 300MHz=2 and f / f m0 =f BB / LO=1200MHz / 300MHz=4, and f / f m0 =2n / m.

[0041] In this way, the length of the transmission line 10 is mλ m0 When set to / 4, f / f m0 If the wavelength is λ = 2n / m, the impedance can be matched and there will be no reflection. m0 As mentioned above, λ m0 =C0 / (f m0 ×√ε r ) can be obtained, but regardless of this formula, the frequency f m0 The wavelength of the transmission line 10 corresponding to m0 It may also be used as.

[0042] 6 is a diagram showing the frequency characteristics of the input impedance of the transmission line 10. Specifically, FIG. 6 shows the frequency characteristics of the input impedance of the transmission line 10. L is set to 50 Ω, the center frequency of the transmission line 10 (the frequency f of the signal propagating through the transmission line 10) is set to 600 MHz, and the length of the transmission line 10 is set to λ m0 / 4 (m=1), and the characteristic impedance Z m0 The input impedance Z of transmission line 10 when in The frequency dependence of is shown below.

[0043] From Figure 6, f=2×f m0 = 600MHz terminating impedance Z L and input impedance Z in It can be seen that the characteristic impedance Z of the transmission line 10 matches with that of the m0 When is far from 50 Ω, the bandwidth narrows, but f=2n×f m0 When tan(πf / 2f) of Eq. m0 ) becomes 0, and Z in =Z L It is obvious that the termination impedance Z L and characteristic impedance Z m0 In other words, even if the transmission line 10 is a line or circuit with an arbitrary impedance value, impedance matching is possible.

[0044] The principle of the present invention is ,difference Traffic lines Suitable for By using differential lines, the present invention can also be applied to a high-frequency circuit 1 (gyrator) using a Gilbert cell mixer as shown in Figure 4, and a circulator using the same. By using this configuration for each transmission line in Figure 4, these transmission lines can be made smaller.

[0045] 4, when the switching frequency (frequency LO of the drive signal) of switching circuits 11 and 12 is 300 MHz, and the RF signal propagating through transmitting terminal 51, antenna terminal 52, receiving terminal 53, first circuit 20, second circuit 30, and third circuit 40 is 900 MHz, the isolation between transmitting terminal 51 and receiving terminal 53 is maximized, the loss between transmitting terminal 51 and antenna terminal 52 is minimized, and the loss between antenna terminal 52 and receiving terminal 53 is minimized. At this time, the frequency of the BB signal propagating through transmission line 10 is down-converted from the RF signal frequency of 900 MHz to 600 MHz.

[0046] Therefore, in the circulator shown in Figure 4, the termination impedance Z L The magnitude of the impedance of the first circuit 20 and the impedance of the second circuit 30 and the characteristic impedance Z of the transmission line 10 m0 Regardless of the magnitude of the impedance, when the RF signal is 900 MHz, the impedance can be matched and the reflection loss in the high-frequency circuit 1 can be suppressed. Therefore, the characteristic impedance Z m0 can be set to a value suitable for miniaturization.

[0047] The switching circuits 11 and 12 are switched as shown in FIGS. 7A to 10B.

[0048] FIG. 7A is a diagram showing the drive signals of the switching circuits 11 and 12 at the first timing.

[0049] FIG. 7B is a diagram showing the switching states of the switching circuits 11 and 12 at the first timing.

[0050] FIG. 8A is a diagram showing the drive signals of the switching circuits 11 and 12 at the second timing.

[0051] FIG. 8B is a diagram showing the switching states of the switching circuits 11 and 12 at the second timing.

[0052] FIG. 9A is a diagram showing the drive signals of the switching circuits 11 and 12 at the third timing.

[0053] FIG. 9B is a diagram showing the switching states of the switching circuits 11 and 12 at the third timing.

[0054] FIG. 10A is a diagram showing the drive signals of the switching circuits 11 and 12 at the fourth timing.

[0055] FIG. 10B is a diagram showing the switching states of the switching circuits 11 and 12 at the fourth timing.

[0056] If the period of the drive signal of the switching frequency LO is T, then T=1 / LO, and the first to fourth timings are T / 4 each.

[0057] At the first timing shown in FIG. 7A, as shown in FIG. 7B, one end of the transmission line 10a is connected to the first circuit 20a, the other end of the transmission line 10a is connected to the second circuit 30b, and one end of the transmission line 10b is connected to the first circuit 20b, and the other end of the transmission line 10b is connected to the second circuit 30a.

[0058] At the second timing shown in FIG. 8A, as shown in FIG. 8B, one end of the transmission line 10a is connected to the first circuit 20a, the other end of the transmission line 10a is connected to the second circuit 30a, one end of the transmission line 10b is connected to the first circuit 20b, and the other end of the transmission line 10b is connected to the second circuit 30b.

[0059] At the third timing shown in FIG. 9A, as shown in FIG. 9B, one end of the transmission line 10a is connected to the first circuit 20b, the other end of the transmission line 10a is connected to the second circuit 30a, and one end of the transmission line 10b is connected to the first circuit 20a, and the other end of the transmission line 10b is connected to the second circuit 30b.

[0060] At the fourth timing shown in FIG. 10A, as shown in FIG. 10B, one end of the transmission line 10a is connected to the first circuit 20b, the other end of the transmission line 10a is connected to the second circuit 30b, one end of the transmission line 10b is connected to the first circuit 20a, and the other end of the transmission line 10b is connected to the second circuit 30a.

[0061] 7B, 8B, 9B, and 10B, only one of the first circuits 20a and 20b is always connected to one end of the transmission line 10 while being switched, and only one of the second circuits 30a and 30b is always connected to the other end of the transmission line 10 while being switched, which enables the high-frequency circuit 1 to function as a gyrator.

[0062] The transmission line 10 may be configured using only passive elements through lumped parameter approximation, or may be configured, for example, by a plurality of cascade-connected circuits. For example, the transmission line 10 may be configured by cascade-connecting circuits each including an inductor and a capacitor as a passive element. For example, the transmission line 10 may be configured by a ladder circuit in which L-type circuits are cascade-connected, or a ladder circuit in which π-type circuits or π-lattice circuits are cascade-connected, for miniaturization.

[0063] 11 is a configuration diagram showing an example of a ladder-type transmission line 10 configured with L-type circuits. As shown in Fig. 11, the transmission line 10 may be configured with a ladder-type circuit in which multiple stages of L-type circuits, each of which is made up of passive elements such as inductors and capacitors, are cascaded.

[0064] FIG. 12 illustrates the isolation characteristics of a circulator incorporating a ladder-type transmission line 10 configured with L-type circuits. This figure shows the isolation between the transmit terminal 51 and the receive terminal 53 when nine and thirty L-type circuits are cascaded. For example, when nine L-type circuits are cascaded, the inductance value of the inductor can be 4.63 nH and the capacitance value of the capacitor can be 0.93 pF. When thirty L-type circuits are cascaded, the inductance value of the inductor can be 1.39 nH and the capacitance value of the capacitor can be 0.28 pF. When nine L-type circuits are cascaded, 26 dB of isolation is achieved at a transmit power of 30 dBm. When thirty L-type circuits are cascaded, the delay time frequency characteristic is flat at 30 dBm, resulting in 33 dB of isolation, which is superior to the isolation achieved when nine L-type circuits are cascaded. However, increasing the number of stages in the L-type circuit increases the size of the circuit.

[0065] However, according to the present invention, the characteristic impedance of the transmission line 10 can be set to any value, and therefore the characteristic impedance of the transmission line 10 may be smaller than the impedance of the first circuit 20 and the impedance of the second circuit 30. When the transmission line 10 is configured with lumped constant elements using inductors, capacitors, etc., the size of the inductors that configure the transmission line 10 can be reduced by setting the characteristic impedance (equivalent characteristic impedance) of the transmission line 10 to a small value, and as a result, the transmission line 10 can be made smaller.

[0066] Fig. 13 is a configuration diagram showing an example of a ladder-type transmission line 10 configured with a π-lattice circuit known for its flat delay time frequency characteristics. As shown in Fig. 13, the transmission line 10 may be configured with a ladder-type circuit in which multiple stages of π-lattice circuits, each consisting of passive elements such as inductors and capacitors, are cascaded. For example, assume that five stages of π-lattice circuits are cascaded.

[0067] For example, to prevent reflection, the terminating impedance Z L (differential impedance) is 100Ω, and the characteristic impedance Z m0 If the differential impedance is 100Ω, then from equation 3 below, L = 8.3nH and C = 0.55pF, which achieves a delay time similar to that achieved when 30 L-type circuits are cascaded, and can be configured more compactly than an L-type circuit.

[0068]

number

[0069] However, even in this case, the inductance value of the inductor is large at 8.3 nH, and when the inductance value of the inductor is large, the size of the inductor also increases, resulting in an increase in the size of the transmission line 10.

[0070] So, f / f m0 = 2n / m, the inductance value of the inductor in the π-Lattice circuit is 0.52nH, the capacitance value of the capacitor is 8.8pF, and the characteristic impedance Z of the transmission line 10 is m0 The differential impedance was set to 6.1Ω. The reflection characteristics of the transmission line 10 at this time are shown in FIG.

[0071] FIG. 14 is a Smith chart showing the impedance characteristics of a ladder-type transmission line 10 configured as a π-lattice circuit.

[0072] As shown in FIG. 14, at 600 MHz, which is the frequency of the signal propagating through the transmission line 10, Z in and Z L is almost equal to the reflection loss. m0 =6.1Ω is 1 / 16 of 100Ω, which means that the inductance value of the inductor can be significantly reduced, that is, the size of the inductor can be significantly reduced.

[0073] When the transmission line 10 is configured as a stripline-based line in which a conductor is formed on a dielectric, such as a microstrip line, a stripline, a coplanar guideline, or a coplanar guideline with a GND, the characteristic impedance of the transmission line 10 may be larger than the impedance of the first circuit 20 and the impedance of the second circuit 30. By increasing the characteristic impedance of the transmission line 10, the line width of the stripline-based line can be narrowed, and as a result, the transmission line 10 can be made smaller. As an example, the characteristic impedance Z of a microstrip line is m0 The approximate formula for is shown in the following formula 4. Here, h is the height of the dielectric that constitutes the microstrip line, and W is the width (line width) of the conductor that constitutes the microstrip line.

[0074]

number

[0075] As shown in Equation 4, in a stripline type line, the line width can be reduced by increasing the characteristic impedance, and therefore the transmission line 10 can be made smaller.

[0076] As described above, the high-frequency circuit 1 includes the transmission line 10, the switching circuit 11 connected to one end of the transmission line 10 and switching the connection between the one end of the transmission line 10 and the plurality of first circuits 20, and the switching circuit 12 connected to the other end of the transmission line 10 and switching the connection between the other end of the transmission line 10 and the plurality of second circuits 30. m0 is the switching frequency of the switching circuits 11 and 12, f is the frequency of the signal propagating through the transmission line 10, and λ m0 is the wavelength for the switching frequency, m is an integer equal to or greater than 1, n is an integer equal to or greater than 0, and the length of the transmission line 10 is mλ m0 / 4, f / f m0 =2n / m.

[0077] f / f m0By setting the switching frequencies of switching circuits 11 and 12 relative to the frequency of the signal propagating through transmission line 10 so that .rho.=2n / m, the characteristic impedance of transmission line 10 can be set to any value. In other words, the characteristic impedance of transmission line 10 can be set to a value that reduces the size of the transmission line, thereby making it possible to miniaturize transmission line 10. This in turn makes it possible to miniaturize the entire circuit to which high-frequency circuit 1 is applied.

[0078] For example, one end of the transmission line 10 may be exclusively connected to one of a plurality of first circuits 20 by a switching circuit 11, and the other end of the transmission line 10 may be exclusively connected to one of a plurality of second circuits 30 by a switching circuit 12.

[0079] One end of the transmission line 10 is exclusively connected to one of the plurality of first circuits 20, and the other end of the transmission line 10 is exclusively connected to one of the plurality of second circuits 30, so that the high-frequency circuit 1 can be operated as a gyrator.

[0080] The high-frequency circuit 1 includes a plurality of transmission lines 10, a switching circuit 11 connected to one end of each of the plurality of transmission lines 10 and switching the connection between each of the one ends of the plurality of transmission lines 10 and a first circuit 20, and a switching circuit 12 connected to the other end of each of the plurality of transmission lines 10 and switching the connection between each of the other ends of the plurality of transmission lines 10 and a second circuit 30. m0 is the switching frequency of the switching circuits 11 and 12, f is the frequency of the signal propagating through the transmission line 10, and λ m0 is the wavelength for the switching frequency, m is an integer equal to or greater than 1, n is an integer equal to or greater than 0, and the length of the transmission line 10 is mλ m0 / 4, f / f m0 =2n / m.

[0081] f / f m0By setting the switching frequencies of switching circuits 11 and 12 relative to the frequency of the signal propagating through transmission line 10 so that .rho.=2n / m, the characteristic impedance of transmission line 10 can be set to any value. In other words, the characteristic impedance of transmission line 10 can be set to a value that reduces the size of the transmission line, thereby making it possible to miniaturize transmission line 10. This in turn makes it possible to miniaturize the entire circuit to which high-frequency circuit 1 is applied.

[0082] For example, the first circuit 20 may be exclusively connected to one end of one of the multiple transmission lines 10 by the switching circuit 11, and the second circuit 30 may be exclusively connected to the other end of one of the multiple transmission lines 10 by the switching circuit 12.

[0083] By providing the high-frequency circuit 1 with a plurality of transmission lines 10, it becomes possible to use transmission lines 10 with a plurality of different characteristic impedances, and the frequency range that the high-frequency circuit 1 can support can be widened.

[0084] For example, the switching circuits 11 and 12 may each be configured by a semiconductor element whose conduction and non-conduction are controlled by a control signal.

[0085] By using semiconductor elements such as MOSFETs in the switching circuits 11 and 12, the high frequency circuit 1 can be applied to high frequency bands.

[0086] For example, the switching frequency of the switching circuits 11 and 12 may be different from the frequency of the signal propagating through the transmission line 10 .

[0087] This allows the high frequency circuit 1 to be applied to a gyrator that uses a mixer that uses a switch.

[0088] For example, the first circuit 20 and the second circuit 30 may each be configured by a second transmission line.

[0089] In this way, the high-frequency circuit 1 can be applied to a circuit configured with a transmission line.

[0090] For example, the first circuit 20 and the second circuit 30 may each be configured with passive elements.

[0091] In this way, the high-frequency circuit 1 can be applied to a circuit configured with passive elements.

[0092] For example, the first circuit 20 and the second circuit 30 may each be configured by a delay circuit made up of passive elements.

[0093] In this way, the high-frequency circuit 1 can be applied to a circuit configured with a delay circuit.

[0094] For example, the transmission line 10 may be configured with a plurality of cascaded circuits, each of which may be configured with a passive element. For example, the equivalent characteristic impedance of the transmission line 10 may be smaller than the impedance of the first circuit 20 and the impedance of the second circuit 30.

[0095] When the transmission line 10 is composed of lumped constant elements such as inductors and capacitors, the characteristic impedance (equivalent characteristic impedance) of the transmission line 10 can be set to a small value, thereby reducing the size of the inductors that make up the transmission line 10, and as a result, the transmission line 10 can be made smaller.

[0096] For example, the transmission line 10 may be configured by a stripline type line. For example, the characteristic impedance of the transmission line 10 may be greater than the impedance of the first circuit 20 and the impedance of the second circuit 30.

[0097] When the transmission line 10 is configured as a stripline-based line in which a conductor is formed on a dielectric, such as a microstrip line, a stripline, a coplanar guideline, or a coplanar guideline with a GND, the line width of the stripline-based line can be narrowed by increasing the characteristic impedance of the transmission line 10, and as a result, the transmission line 10 can be made smaller.

[0098] (Other embodiments) Although the high-frequency circuit 1 according to the present invention has been described above using embodiments, the present invention is not limited to the above embodiments. The present invention also includes other embodiments realized by combining any of the components in the above embodiments, modifications obtained by applying various modifications to the above embodiments that would occur to those skilled in the art without departing from the spirit of the present invention, and various devices incorporating the high-frequency circuit 1 according to the present invention. [Industrial Applicability]

[0100] The present invention can be widely used in high frequency systems, such as gyrators, circulators, selector circuits, multiplexer circuits, demultiplexer circuits, serial-parallel conversion circuits, or parallel-serial conversion circuits, as high frequency circuits that switch paths. [Explanation of symbols]

[0101] 1. High-frequency circuits 10, 10a, 10b Transmission lines 11, 12 Switching circuit 20, 20a, 20b 1st circuit 30, 30a, 30b 2nd circuit 40, 40a, 40b 3rd Circuit 51 Transmission terminal 52 Antenna terminal 53 Receiving terminal

Claims

1. a first transmission line; a first switching circuit connected to one end of the first transmission line and switching a connection between the one end of the first transmission line and a plurality of first circuits; a second switching circuit connected to the other end of the first transmission line and configured to switch a connection between the other end of the first transmission line and a plurality of second circuits; f ｍ０ is the switching frequency of the first switching circuit and the second switching circuit, f is the frequency of the signal propagating through the first transmission line, and λ ｍ０ is the wavelength for the switching frequency, m is an integer equal to or greater than 1, n is an integer equal to or greater than 0, and the length of the first transmission line is mλ ｍ０ / 4, then f / f ｍ０ = 2n / m, High frequency circuits.

2. one end of the first transmission line is exclusively connected to one first circuit among the plurality of first circuits by the first switching circuit; the other end of the first transmission line is exclusively connected to one second circuit among the plurality of second circuits by the second switching circuit; The high frequency circuit according to claim 1 .

3. a plurality of first transmission lines; a first switching circuit connected to one end of each of the plurality of first transmission lines and switching a connection between each of the one ends of the plurality of first transmission lines and a first circuit; a second switching circuit connected to the other end of each of the plurality of first transmission lines and switching a connection between the other end of each of the plurality of first transmission lines and a second circuit, f ｍ０ is the switching frequency of the first switching circuit and the second switching circuit, f is the frequency of the signal propagating through the first transmission line, and λ ｍ０ is the wavelength for the switching frequency, m is an integer equal to or greater than 1, n is an integer equal to or greater than 0, and the length of the first transmission line is mλ ｍ０ / 4, then f / f ｍ０ = 2n / m, High frequency circuits.

4. the first circuit is exclusively connected to one end of one of the plurality of first transmission lines by the first switching circuit; the second circuit is exclusively connected to the other end of one of the plurality of first transmission lines by the second switching circuit; The high frequency circuit according to claim 3.

5. the first switching circuit and the second switching circuit are each configured by a semiconductor element whose conduction and non-conduction are controlled by a control signal; The high-frequency circuit according to any one of claims 1 to 4.

6. the switching frequency is different from the frequency of the signal propagating through the first transmission line; The high-frequency circuit according to any one of claims 1 to 4.

7. the first circuit and the second circuit are each formed by a second transmission line; The high-frequency circuit according to any one of claims 1 to 4.

8. the first circuit and the second circuit are each composed of passive elements; The high-frequency circuit according to any one of claims 1 to 4.

9. the first circuit and the second circuit are each formed of a delay circuit made up of passive elements; The high frequency circuit according to claim 8.

10. the first transmission line is configured by a plurality of circuits connected in cascade, Each of the plurality of circuits is composed of passive elements. The high-frequency circuit according to any one of claims 1 to 4.

11. an equivalent characteristic impedance of the first transmission line is smaller than an impedance of the first circuit and an impedance of the second circuit; The high frequency circuit according to claim 10.

12. the first transmission line is configured by a stripline-based line; The high-frequency circuit according to any one of claims 1 to 4.

13. a characteristic impedance of the first transmission line is greater than an impedance of the first circuit and an impedance of the second circuit; The high frequency circuit according to claim 12.

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