High-frequency circuit and method for detecting anomalies therein

Abstract

To provide a high-frequency circuit and an abnormality detection method therefor that are capable of detecting abnormalities such as disconnection of a transmission line for a high-frequency signal with a compact configuration.SOLUTION: A high-frequency circuit 1 includes a capacitor 32 which is connected to main lines 14 and 15 of a transmission line 10, a resistor 25 which is connected in parallel between two terminals of the capacitor 32, and bias terminals 42a and 43a which are connected to the main lines 14 and 15, are respectively arranged on both outer sides of an inspection target circuit 50 including the resistor 25 and the capacitor 32, and are connected to a measurement device 60 at the time of abnormality diagnosis. The measurement device 60 applies a direct-current voltage or a direct-current current to the inspection target circuit 50 via the bias terminals 42a and 43a, measures at least one type of measurement value among a resistance value, a voltage, and a current between the bias terminals 42a and 43a, and detects whether or not at least one type of abnormality including disconnection of the main lines 14 and 15 or short-circuiting of the capacitor 32 has occurred on the basis of the measurement value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a high-frequency circuit and an abnormality detection method thereof, and particularly to a high-frequency circuit for a frequency band from a microwave band to a terahertz band and an abnormality detection method thereof.

Background Art

[0002] Conventionally, for example, high-frequency circuits such as amplifiers and mixers for a frequency band from a microwave band to a terahertz band have been used, and it is required to detect disconnection of a high-frequency signal transmission line included in these high-frequency circuits, failures of semiconductors such as capacitors and transistors, and the like.

[0003] FIG. 9 is a diagram showing an example of the configuration of a conventional high-frequency circuit. As shown in FIG. 9, a partial discharge detection device 70 disclosed in Patent Document 1 includes a sensor 71 for detecting electromagnetic waves of partial discharge, a matching resistor 72 for the sensor, a cable 73, a parallel circuit including a filter 74 including a capacitor inserted in series in a signal line and a switch 75, potential forming circuits having input resistors 76 and 77 and a circuit power supply 78 for forming the potential at point A, and a partial discharge determination / self-diagnosis circuit 81 for determining abnormalities such as disconnection of the matching resistor 72 for the sensor or disconnection of the cable 73 based on the potential at point A after controlling the switch 75 to a closed state during self-diagnosis.

[0004] Further, Patent Document 1 describes that by outputting a simulated pulse signal 86 to a simulated pulse generator 82 for self-diagnosis under the control of the partial discharge determination / self-diagnosis circuit 81, during self-diagnosis, the switch 75 is controlled to a closed state to ensure DC conduction to the signal line, and thus abnormalities such as disconnection of the sensor matching resistor can be detected based on the input unit potential, and the soundness of the device can be self-diagnosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, conventional technologies such as those disclosed in Patent Document 1 have the problem that the circuit area increases due to the placement of a switch circuit and a control circuit in parallel with a circuit containing a capacitor.

[0007] The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a high-frequency circuit and a method for detecting abnormalities such as disconnections in high-frequency signal transmission lines, with a compact configuration. [Means for solving the problem]

[0008] To solve the above problems, the high-frequency circuit according to the present invention is a high-frequency circuit (1,2) in which a transmission line (10) for transmitting a high-frequency signal is provided on a dielectric substrate (100), comprising: an electronic component (32,34,35) having a plurality of terminals connected to the main line (12~17) of the transmission line; a resistor (25,26) connected in parallel between two terminals of the plurality of terminals of the electronic component through which no DC current flows; and a pair of resistors connected to the main line and positioned on both sides of the circuit to be inspected (50,52) including the resistor and the electronic component, and connected to a measuring device (60) when an abnormality is diagnosed. The measuring device comprises measuring terminals (41a, 42a, 43a, 44a), a measuring circuit (61) that applies a DC voltage or DC current to the circuit under test via the pair of measuring terminals and measures at least one of the following values: the resistance between the pair of measuring terminals, the voltage between the pair of measuring terminals, and the current flowing between the pair of measuring terminals, and an abnormality detection unit (62) that detects whether or not at least one abnormality has occurred, including a break in the main line or a short circuit in the electronic component, based on the measured values ​​measured by the measuring circuit.

[0009] With this configuration, the high-frequency circuit according to the present invention can detect whether or not at least one type of abnormality has occurred in the circuit under inspection, including a break in the main transmission line or a short circuit in an electronic component, in a compact configuration.

[0010] Furthermore, the high-frequency circuit according to the present invention has the advantage of being able to detect the above-mentioned abnormalities by DC measurement alone, without using expensive high-frequency measuring instruments.

[0011] Furthermore, the high-frequency circuit according to the present invention further comprises a first branch line (21, 23) that branches off from the main line and connects one terminal of the two terminals of the electronic component to one end of the resistor, and a second branch line (22, 24) that branches off from the main line and connects the other terminal of the two terminals of the electronic component to the other end of the resistor, wherein the length of the first branch line and the second branch line from the main line to the resistor is an integer multiple of approximately 1 / 2 of the wavelength of the high-frequency signal transmitted through the first branch line and the second branch line.

[0012] With this configuration, the high-frequency circuit according to the present invention can ensure that the impedance of the path consisting of the resistor, the first branch line, and the second branch line is sufficiently high when viewed from the main transmission line, so as not to adversely affect the pass-through gain of the entire high-frequency circuit.

[0013] Furthermore, the high-frequency circuit according to the present invention includes a first main line (14) and a second main line (15) which are capacitively coupled to each other via the electronic components, and the first main line conductor of the first main line, the second main line conductor of the second main line, the first branch conductor of the first branch line, and the second branch conductor of the second branch line are provided on the surface of the dielectric substrate, and the high-frequency circuit includes a metal layer (301) provided above the dielectric substrate and the first main line conductor and The electronic component may further include an air bridge (303) connecting the metal layers, and a dielectric film (304) provided between the second main line conductor and the metal layers, wherein the first branch conductor is integrally formed with the first main line conductor, and the second branch conductor is integrally formed with the second main line conductor, and the electronic component may be configured as a capacitor (32) including the metal layer which also serves as one of the terminals, the dielectric film, and the second main line conductor which also serves as the other terminal.

[0014] Furthermore, the high-frequency circuit according to the present invention includes a first main line (14) and a second main line (15) that are capacitively coupled to each other via the electronic components, the first main line conductor of the first main line and the second main line conductor of the second main line are provided on the surface of the dielectric substrate, the high-frequency circuit includes a first metal wiring (312) provided below the first main line conductor, a second metal wiring (313) provided below the second main line conductor, a metal layer (311) provided above the first and second metal wirings, a dielectric film (319) provided between the second metal wiring and the metal layer, a first via hole (316) connecting the first main line conductor and the first metal wiring, and the second main line conductor and the second metal The capacitor (32) further comprises a second via hole (317) for connecting wiring and a third via hole (318) for connecting the first metal wiring and the metal layer, wherein the first branch conductor of the first branch line provided below the first main line conductor is integrally formed with the first metal wiring, and the second branch conductor of the second branch line provided below the second main line conductor is integrally formed with the second metal wiring, and the electronic component is a capacitor (32) including the metal layer which also serves as one of the terminals, the dielectric film, and the second metal wiring which also serves as the other terminal, and the abnormality detection unit may further be configured to detect whether or not any of the first metal wiring, the second metal wiring, the first via hole, and the second via hole is broken.

[0015] With this configuration, the high-frequency circuit according to the present invention allows the abnormality detection unit to detect whether or not any of the first via hole, the second via hole, the first metal wiring, or the second metal wiring is disconnected.

[0016] Furthermore, the high-frequency circuit according to the present invention includes a first main line (12) connected to one terminal of the electronic component and a second main line (13) connected to the other terminal of the electronic component, wherein the first main line conductor of the first main line and the second main line conductor of the second main line are provided on the surface of the dielectric substrate, and the high-frequency circuit includes a first metal wiring (321) provided below the first main line conductor, a second metal wiring (322) provided below the second main line conductor, a third metal wiring (325) provided below the first metal wiring, a fourth metal wiring (326) provided below the second metal wiring, a fifth metal wiring (329) provided below the third metal wiring and connected to one terminal, a sixth metal wiring (330) provided below the fourth metal wiring and connected to the other terminal, and the first main line conductor and the The device further comprises a plurality of via holes (331-336) connecting the first metal wiring, the third metal wiring, and the fifth metal wiring, and the second main line conductor, the second metal wiring, the fourth metal wiring, and the sixth metal wiring, wherein the first branch conductor of the first branch line provided below the third metal wiring is integrally formed with the fifth metal wiring, and the second branch conductor of the second branch line provided below the fourth metal wiring is integrally formed with the sixth metal wiring, and the electronic component is an emitter-grounded transistor (34, 35) with one terminal being the base and the other terminal being the collector, and the abnormality detection unit may further detect whether any of the first metal wiring, the second metal wiring, the third metal wiring, the fourth metal wiring, the fifth metal wiring, the sixth metal wiring, and the plurality of via holes are disconnected.

[0017] With this configuration, the high-frequency circuit according to the present invention allows the abnormality detection unit to detect whether or not any of the first via hole, second via hole, third via hole, fourth via hole, fifth via hole, sixth via hole, first metal wiring, second metal wiring, third metal wiring, fourth metal wiring, fifth metal wiring, and sixth metal wiring are disconnected.

[0018] Further, the abnormality detection method according to the present invention is a high-frequency circuit (1, 2) in which a transmission line (10) for transmitting a high-frequency signal is provided on a dielectric substrate (100), and electronic components (32, 34, 35) having a plurality of terminals connected to the main lines (12 to 17) of the transmission line, and resistors (25, 26) connected in parallel between two terminals through which no direct current flows among the plurality of terminals of the electronic components, and a pair of measurement terminals (41a, 42a, 43a, 44a) that are respectively disposed on both outer sides of a test target circuit (50, 52) connected to the main line and including the resistor and the electronic component, and are connected to a measuring device (60) during abnormality diagnosis. The abnormality detection method for the high-frequency circuit includes: the measuring device applying a direct current voltage or a direct current to the test target circuit through the pair of measurement terminals, and measuring at least one type of measurement value among the resistance value between the pair of measurement terminals, the voltage between the pair of measurement terminals, and the current flowing between the pair of measurement terminals by a measurement circuit (61), and an abnormality detection unit (62) detecting whether or not at least one type of abnormality including disconnection of the main line or a short circuit of the electronic component has occurred based on the measurement value measured by the measurement circuit.

Advantages of the Invention

[0019] The present invention provides a high-frequency circuit and an abnormality detection method thereof that can detect abnormalities such as disconnection of a transmission line for high-frequency signals with a small configuration.

Brief Description of the Drawings

[0020] [Figure 1] It is a diagram showing the configuration of a high-frequency circuit according to a first embodiment of the present invention. [Figure 2] (a) is a graph showing the passing characteristic S21 of the high-frequency circuit in a normal state, and (b) is a graph showing the passing characteristic S21 of the high-frequency circuit in an abnormal state. [Figure 3] It is a diagram showing the configuration of the high-frequency circuit in an abnormal state. [Figure 4](a) is a top view of a circuit under test included in the high-frequency circuit according to the first embodiment of the present invention, (b) is a cross-sectional view taken along line A-A of (a), and (c) is a cross-sectional view taken along line B-B of (a). [Figure 5] (a) is a graph showing the passing characteristic S21 of the high-frequency circuit when the line lengths of the first branch line and the second branch line in the circuit under test are set to 1 / 4 of the wavelength of the high-frequency signal, and (b) is a graph showing the passing characteristic S21 of the high-frequency circuit when the line lengths of the first branch line and the second branch line in the circuit under test are set to 1 / 2 of the wavelength of the high-frequency signal. [Figure 6] (a) is a top view showing another configuration example of the circuit under test, (b) is a cross-sectional view taken along line A-A of (a), and (c) is a cross-sectional view taken along line B-B of (a). [Figure 7] It is a diagram showing the configuration of the high-frequency circuit according to the second embodiment of the present invention. [Figure 8] (a) is a top view of a circuit under test included in the high-frequency circuit according to the second embodiment of the present invention, and (b) is a cross-sectional view taken along line A-A of (a). [Figure 9] It is a diagram showing the configuration of a conventional high-frequency circuit.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the high-frequency circuit and its abnormality detection method according to the present invention will be described with reference to the drawings. The high-frequency circuit of the present invention is for amplifying a high-frequency signal exceeding, for example, 200 GHz.

[0022] (First Embodiment) First, the configuration of the high-frequency circuit according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 6.

[0023] Figure 1 shows the configuration of the high-frequency circuit 1 of this embodiment. As shown in Figure 1, the high-frequency circuit 1 includes an input terminal IN into which a high-frequency signal is input, an output terminal OUT which outputs a high-frequency signal, a transmission line 10 connecting the input terminal IN to the output terminal OUT to transmit the high-frequency signal, a capacitor 32, transistors 34, 35, bias circuits 41, 42, 43, 44, bias terminals 41a, 42a, 43a, 44a, a circuit to be tested 50, and a measuring device 60.

[0024] The transmission line 10 consists of main lines 11-18 and branch lines 21 and 22. A DC blocking capacitor 32 is inserted in series between main line 14, which is the first main line, and main line 15, which is the second main line, with the two terminals (electrodes) of the capacitor 32 electrically connected to main line 14 and main line 15, respectively. A resistor 25 is connected in parallel between the two terminals of the capacitor 32. The capacitor 32 is an example of an electronic component of the high-frequency circuit 1, and the two terminals mentioned above correspond to two terminals through which no DC current flows.

[0025] The main lines 14 and 15, the branch line 21 as the first branch line, the branch line 22 as the second branch line, the resistor 25, and the capacitor 32 constitute the circuit 50 to be inspected.

[0026] Transistors 34 and 35 are, for example, NPN bipolar transistors and are common-emitter connected. That is, the high-frequency circuit 1 functions as an amplifier circuit in which two common-emitter transistors 34 and 35 are connected in a two-stage configuration.

[0027] Note that transistors 34 and 35 are not limited to NPN bipolar transistors, but may also be PNP bipolar transistors or field-effect transistors, for example.

[0028] The bias circuit 41 is a circuit that, during the normal operation of the high-frequency circuit 1, supplies a bias voltage applied to the bias terminal 41a from a DC power supply (not shown) to the base of the transistor 34.

[0029] The bias circuit 42 is a circuit that, during the normal operation of the high-frequency circuit 1, supplies a bias voltage applied to the bias terminal 42a from a DC power supply (not shown) to the collector of the transistor 34.

[0030] The bias circuit 43 is a circuit that, during the normal operation of the high-frequency circuit 1, supplies a bias voltage applied to the bias terminal 43a from a DC power supply (not shown) to the base of the transistor 35.

[0031] The bias circuit 44 is a circuit that, during the normal operation of the high-frequency circuit 1, supplies a bias voltage applied to the bias terminal 44a from a DC power supply (not shown) to the collector of the transistor 35.

[0032] These bias circuits 41-44 are designed with sufficiently high impedance to minimize their influence on the characteristics of the high-frequency circuit 1.

[0033] The bias circuit 41 and bias terminal 41a are connected between the main lines 11 and 12 in the transmission line 10. The bias circuit 42 and bias terminal 42a are connected between the main lines 13 and 14 in the transmission line 10. The bias circuit 43 and bias terminal 43a are connected between the main lines 15 and 16 in the transmission line 10. The bias circuit 44 and bias terminal 44a are connected between the main lines 17 and 18 in the transmission line 10.

[0034] In other words, in this embodiment, bias terminals 42a and 43a are electrically connected to the main lines 14 and 15 via bias circuits 42 and 43, respectively. The bias terminals 42a and 43a are located on the outside of the main lines 14 and 15 that constitute the circuit under inspection 50, and also serve as a pair of measuring terminals that are connected to the measuring device 60 when an abnormality is diagnosed.

[0035] Figure 2(a) shows the pass-through characteristics S from the input terminal IN to the output terminal OUT of the high-frequency circuit 1 under normal conditions. 21This is a graph showing the following. On the other hand, Figure 2(b) shows the passage characteristics S when there is an abnormality in which the main line 14 or main line 15 in the circuit 50 under inspection is broken, as shown in Figure 3. 21 This shows that the capacitance of capacitor 32 is 1pF and the resistance of resistor 25 is 1kΩ.

[0036] In the graphs in Figures 2(a) and 2(b), if we focus on 275 GHz within the operating frequency band of high-frequency circuit 1, which is 220 GHz to 330 GHz, we can see that the pass gain under normal conditions is 6.7 dB, while the pass gain under abnormal conditions drops to 2.4 dB.

[0037] Thus, the pass-through characteristic S from the input terminal IN to the output terminal OUT is as follows: 21 If the value drops below normal, it may indicate some kind of abnormality, such as a break in the main lines 14, 15 or connecting conductors, or a short circuit in capacitor 32 or transistors 34, 35.

[0038] The measuring device 60, for example, measures the passage characteristics S as described above. 21 If an abnormality is detected, measurements are taken to more clearly identify the cause, and the system includes a measurement circuit 61, an abnormality detection unit 62, and a display unit 63.

[0039] The measurement circuit 61 is connected to the bias terminals 42a and 43a when diagnosing an abnormality in the high-frequency circuit 1, and measures at least one of the following values: the resistance between the bias terminals 42a and 43a, the voltage between the bias terminals 42a and 43a, and the current flowing between the bias terminals 42a and 43a.

[0040] For example, the measurement circuit 61 applies a constant DC voltage to the circuit under test 50 via the bias terminals 42a and 43a to measure the current flowing between the bias terminals 42a and 43a, and calculates the resistance value between the bias terminals 42a and 43a based on the measurement result.

[0041] Alternatively, the measurement circuit 61 may apply a constant DC current to the circuit under test 50 via the bias terminals 42a and 43a to measure the voltage between the bias terminals 42a and 43a, and calculate the resistance value between the bias terminals 42a and 43a based on the measurement result.

[0042] Furthermore, the measurement circuit 61 may calculate the resistance value of the circuit under test 50 by subtracting the known resistance values ​​of the bias circuits 42 and 43 from the resistance value between the bias terminals 42a and 43a.

[0043] The abnormality detection unit 62 is configured to detect whether or not at least one type of abnormality has occurred, including a break in the main lines 14 and 15, a break in the connecting conductor described later, or a short circuit in the capacitor 32, based on the measurement values ​​measured by the measurement circuit 61.

[0044] For example, if the capacitance of capacitor 32 is C1 [pF] and the resistance of resistor 25 is R1 [Ω], the normal impedance of the circuit under test 50 is 1 / {(1 / R1)+(jωC1)}, and a current corresponding to R1 flows between the bias terminals 42a and 43a.

[0045] On the other hand, if there is a break in the main lines 14, 15 or the connecting conductor, R1 is equivalent to being infinite, so the impedance of the circuit under test 50 becomes 1 / {(1 / ∞)+(jωC1)}, and no current flows between the bias terminals 42a and 43a.

[0046] Therefore, the abnormality detection unit 62 determines that there is a break in at least one of the main lines 14, 15 and the connecting conductor when the resistance value measured by the measurement circuit 61 is equivalent to an infinite value.

[0047] If resistor 25 were not connected in parallel with capacitor 32, it would be impossible to distinguish whether the current is not flowing between bias terminals 42a and 43a due to the DC blocking effect of capacitor 32, or due to a break in the main lines 14 and 15.

[0048] Furthermore, if the original capacitance of capacitor 32 is C1 [pF] and the resistance of resistor 25 placed in parallel is R1 [Ω], then when capacitor 32 is short-circuited, C1 = ∞. In this case, the impedance of the circuit under test 50 is 1 / {(1 / R1)+(jω∞)}, and current flows between bias terminals 42a and 43a regardless of R1.

[0049] Therefore, the abnormality detection unit 62 determines that the capacitor 32 is short-circuited when the current measured by the measurement circuit 61 does not fall within the current range expected from the normal impedance of the circuit under inspection 50.

[0050] The display unit 63 consists of a display device such as an LCD (Liquid Crystal Display) that displays a GUI (Graphical User Interface) such as soft keys, and is configured to display the details of the abnormality detected by the abnormality detection unit 62.

[0051] Figures 4(a) to 4(c) show specific configuration examples of the circuit 50 to be inspected. Figure 4(a) is a top view of the circuit 50 to be inspected, Figure 4(b) is a cross-sectional view of Figure 4(a) along line AA, and Figure 4(c) is a cross-sectional view of Figure 4(a) along line BB.

[0052] As shown in Figure 4(b), the circuit 50 under inspection has a multilayer structure consisting of three layers, from the first wiring layer to the third wiring layer.

[0053] A metal layer 301, which constitutes one of the electrodes of the capacitor 32, is provided in the first wiring layer above the dielectric substrate 100.

[0054] The second wiring layer on the surface of the dielectric substrate 100 is provided with a first main line conductor 141 that constitutes part of the main line 14, a second main line conductor 151 that constitutes part of the main line 15, a first branch conductor 211 that constitutes part of the branch line 21, and a second branch conductor 212 that constitutes part of the branch line 22. Part of the second main line conductor 151 constitutes the other electrode of the capacitor 32.

[0055] On the third wiring layer on the back surface of the dielectric substrate 100, a grounding conductor layer 302 is provided as a common high-frequency ground (RF ground) for the main lines 14, main line 15, branch line 21, and branch line 22, each of which constitutes a part of these lines.

[0056] The metal layer 301 and the first main line conductor 141 are electrically connected by an air bridge 303. A dielectric film 304 is provided between the metal layer 301 and a portion of the second main line conductor 151. That is, the metal layer 301, a portion of the second main line conductor 151, and the dielectric film 304 constitute a capacitor 32, and the first main line conductor 141 and the second main line conductor 151 are capacitively coupled to each other via the capacitor 32.

[0057] The first branch conductor 211 branches off from the first main line conductor 141 and electrically connects a metal layer 301, which also serves as one terminal of the capacitor 32, and one end of a resistor 25 formed of thin metal film, via an air bridge 303. The first branch conductor 211 is integrally formed with the first main line conductor 141.

[0058] The second branch conductor 212 branches off from the second main line conductor 151 and electrically connects the second main line conductor 151, which also serves as the other terminal of the capacitor 32, to the other end of the resistor 25. The second branch conductor 212 is integrally formed with the second main line conductor 151.

[0059] Furthermore, the tip portions of the first branch conductor 211 and the second branch conductor 212 on the resistor 25 side are pads 211a and 212a, respectively, which are wider than the width of the resistor 25. This is to take into consideration the low alignment accuracy of film formation during the manufacturing process when a thin-film ceramic substrate is used as the dielectric substrate 100.

[0060] The lengths of the branch lines 21 and 22 from the main lines 14 and 15 of the transmission line 10 to the resistor 25 are integer multiples of approximately half the wavelength λg of the high-frequency signal transmitted through the branch lines 21 and 22, that is, integer multiples of the electrical length of 180°. Here, the wavelength λg refers to the effective wavelength, taking into account the wavelength shortening effect due to the dielectric properties of the dielectric substrate 100.

[0061] By making the lengths of branch lines 21 and 22 integer multiples of the electrical length of 180°, the impedance of the path consisting of resistor 25, branch line 21, and branch line 22 can be made sufficiently high when viewed from the main lines 11-18 of transmission line 10.

[0062] In the configuration shown in Figures 4(a) to 4(c), the pads 211a and 212a of the first branch conductor 211 and the second branch conductor 212 are capacitive. Therefore, it goes without saying that the impedance design of the path consisting of the resistor 25, the branch line 21, and the branch line 22 must take into account the capacitive nature of these pads 211a and 212a.

[0063] Figure 5(a) shows the transmission characteristics S from the input terminal IN to the output terminal OUT of the high-frequency circuit 1 when the length of branch lines 21 and 22 is set to approximately 1 / 4 of the wavelength λg of the high-frequency signal transmitted through branch lines 21 and 22 in the circuit 50 under inspection shown in Figures 4(a) to (c). 21 This is a graph showing that.

[0064] On the other hand, Figure 5(b) shows the transmission characteristics S from the input terminal IN to the output terminal OUT of the high-frequency circuit 1 when the length of the branch lines 21 and 22 is set to approximately 1 / 2 of the wavelength λg of the high-frequency signal transmitted through the branch lines 21 and 22 in the circuit 50 under inspection shown in Figures 4(a) to (c). 21 This is a graph showing [the relationship between the graph and the data].

[0065] In the graph in Figure 5(a), the pass-through gain for branch lines 21 and 22 when the line length is λg / 4 is -34dB at 275GHz, indicating a significant drop in pass-through gain around 274GHz.

[0066] On the other hand, in the graph in Figure 5(b), the pass-through gain when the line lengths of branch lines 21 and 22 are λg / 2 is 6.7 dB at 275 GHz, indicating that a good pass-through gain without dips is obtained in the operating frequency band of 220 GHz to 330 GHz. In other words, it can be confirmed that the path consisting of resistor 25, branch line 21, and branch line 22 has sufficiently high impedance and does not adversely affect the pass-through gain of the entire high-frequency circuit 1.

[0067] A specific example of the configuration of the circuit 50 to be inspected, shown in Figures 4(a) to (c), is as follows:

[0068] The dielectric substrate 100 is a ceramic substrate with a substrate thickness H of 100 μm. The main lines 14 and 15 are microstrip lines with a width W of 100 μm for the first main line conductor 141 and the second main line conductor 151, and an impedance of 50 Ω. The width of the air bridge 303 is 100 μm, which is equal to the width W of the first main line conductor 141 and the second main line conductor 151. The pads 211a and 212a of the first branch conductor 211 and the second branch conductor 212 are square in shape, with each side being 50 μm wider than the width of the resistor 25.

[0069] Alternatively, the dielectric substrate 100 may be a resin substrate or a quartz glass substrate. For example, as the resin substrate, fluororesin, liquid crystal polymer, BT resin (bismaleimide-triazine resin), etc., can be used. For example, the dielectric substrate 100 may be made by laminating multiple resin substrates together, or it may be a single-layer resin substrate.

[0070] Figures 6(a) to 6(c) show examples of other configurations of the circuit to be inspected 50, specifically an example where the circuit to be inspected 50 is configured within a semiconductor IC (Integrated Circuit). Figure 6(a) is a top view of the circuit to be inspected 50, Figure 6(b) is a cross-sectional view of Figure 6(a) along line AA, and Figure 6(c) is a cross-sectional view of Figure 6(a) along line BB.

[0071] As shown in Figure 6(b), the dielectric substrate 100 consists of, for example, a lower substrate 110 and an upper substrate 120.

[0072] The lower substrate 110 is a semiconductor substrate made of any semiconductor material such as GaAs, GaN, InP, or Si.

[0073] The upper substrate 120 is made of a single-layer or multi-layer material with a relatively low dielectric constant, such as BCB (benzocyclobutene) or SiO2. Note that the upper substrate 120 is not shown in Figure 6(a).

[0074] As shown in Figure 6(b), the circuit under inspection 50 has a multilayer structure consisting of three layers, from the first wiring layer to the third wiring layer. In other words, the circuit under inspection 50 is constructed by stacking multiple dielectric layers and wiring layers on the surface side of the lower substrate 110, which is a semiconductor substrate.

[0075] The first wiring layer on the surface of the upper substrate 120 is provided with a first main line conductor 141 that constitutes part of the main line 14 and a second main line conductor 151 that constitutes part of the main line 15.

[0076] A metal layer 311, which constitutes one of the electrodes of the capacitor 32, is provided in the second wiring layer within the upper substrate 120.

[0077] The third wiring layer on the surface of the lower substrate 110 is provided with a first branch conductor 211 which constitutes part of the branch line 21, a second branch conductor 212 which constitutes part of the branch line 22, a first metal wiring 312, a second metal wiring 313, a grounding conductor layer 314 which constitutes part of the main line 14, and a grounding conductor layer 315 which constitutes part of the main line 15.

[0078] The first branch conductor 211 and the first metal wiring 312 are located below the first main line conductor 141, and the second branch conductor 212 and the second metal wiring 313 are located below the second main line conductor 151.

[0079] Grounding conductor layers 314 and 315 are provided as RF grounds for main lines 14 and 15, respectively. Furthermore, the third wiring layer is provided with grounding conductor layers (not shown) that constitute a part of branch lines 21 and 22, respectively, and serve as RF grounds.

[0080] A portion of the second metal wiring 313 constitutes the other electrode of the capacitor 32.

[0081] The first main line conductor 141 and the first metal wiring 312 are electrically connected by a first via hole 316. The first branch conductor 211 is integrally formed with the first metal wiring 312 and is electrically connected to the first main line conductor 141 via the first via hole 316.

[0082] The second main line conductor 151 and the second metal wiring 313 are electrically connected by a second via hole 317. The second branch conductor 212 is integrally formed with the second metal wiring 313 and is electrically connected to the second main line conductor 151 via the second via hole 317.

[0083] The first via hole 316 and the second via hole 317, as well as the first metal wiring 312 and the second metal wiring 313, constitute a connecting conductor.

[0084] For example, the inner diameter TH of the first via hole 316 and the second via hole 317 is 2.4 μm, and the size of the pads 142 and 152 formed on the tip portions of the first main line conductor 141 and the second main line conductor 151 for the first via hole 316 and the second via hole 317 is three times the inner diameter TH.

[0085] The first metal wiring 312 and the metal layer 311 provided above the first metal wiring 312 and the second metal wiring 313 are electrically connected by a third via hole 318.

[0086] The first via hole 316 and the second via hole 317 are formed by depositing or embedding a conductive material such as gold or copper into a through hole that penetrates from the front surface to the back surface of the upper substrate 120. The third via hole 318 is formed by depositing or embedding a conductive material such as gold or copper into a through hole that penetrates between the second wiring layer and the third wiring layer within the upper substrate 120. The through holes for the first to third via holes 316 to 318 are formed by drilling holes in the upper substrate 120 with a drill or laser. The cross-sectional shape of the through hole is usually a circle, but it may be any shape such as an ellipse, square, or rectangle.

[0087] Furthermore, a dielectric film 319 is provided between the metal layer 311 and a portion of the second metal wiring 313. That is, the metal layer 311, a portion of the second metal wiring 313, and the dielectric film 319 constitute a capacitor 32, and the first main line conductor 141 and the second main line conductor 151 are capacitively coupled to each other via the capacitor 32.

[0088] The first branch conductor 211 is configured to electrically connect a metal layer 311, which also serves as one terminal of the capacitor 32, to one end of a resistor 25 formed of a thin metal film, via a third via hole 318. The second branch conductor 212 is configured to electrically connect a second metal wiring 313, which also serves as the other terminal of the capacitor 32, to the other end of the resistor 25.

[0089] Furthermore, the tip portions of the first branch conductor 211 and the second branch conductor 212 on the resistor 25 side have a pad shape that is approximately the same as the width of the resistor 25. This is because, when manufacturing the dielectric substrate 100 by a semiconductor process, the alignment accuracy of film formation is higher compared to the configuration shown in Figure 4(a), so it is generally not required to place pads wider than the width of the resistor 25 at both ends.

[0090] Similar to the configuration of the circuit under inspection 50 shown in Figure 4(a), the lengths of the branch lines 21 and 22 are integer multiples of approximately half the wavelength λg of the high-frequency signal transmitted through the branch lines 21 and 22, that is, integer multiples of the electrical length of 180°.

[0091] In the configuration shown in Figures 6(a) to (c), for example, if the upper substrate 120 is made of BCB, its thickness H is 3 μm. The first to third wiring layers are made of, for example, gold. Main lines 14 and 15 are microstrip lines with a width W of 5.3 μm for the first main line conductor 141 and the second main line conductor 151, and an impedance of 50 Ω.

[0092] As described above, in this embodiment, the high-frequency circuit 1 has a resistor 25 connected in parallel between the two terminals (electrodes) of the capacitor 32, and measures the resistance, voltage, or current of the circuit under test 50, which includes the parallel circuit of the capacitor 32 and the resistor 25, via the bias terminals 42a and 43a.

[0093] As a result, the high-frequency circuit 1 and its abnormality detection method according to this embodiment can detect whether or not at least one type of abnormality has occurred in the circuit 50 under inspection, including a break in the main lines 14 and 15 of the transmission line 10, a break in the connecting conductor, or a short circuit of the capacitor 32 as an electronic component, all in a compact configuration.

[0094] Furthermore, the high-frequency circuit 1 and its abnormality detection method according to this embodiment have the advantage of being able to detect the above-mentioned abnormality by DC measurement alone, without using expensive high-frequency measuring equipment.

[0095] Furthermore, in the high-frequency circuit 1 according to this embodiment, the line lengths of the branch lines 21 and 22 are integer multiples of approximately 1 / 2 of the wavelength λg of the high-frequency signal transmitted through the branch lines 21 and 22.

[0096] As a result, the high-frequency circuit 1 and its abnormality detection method according to this embodiment can ensure that the impedance of the path consisting of the resistor 25, branch line 21, and branch line 22 is sufficiently high when viewed from the main lines 11 to 18 of the transmission line 10, so as not to adversely affect the pass-through gain of the entire high-frequency circuit 1.

[0097] Furthermore, in the high-frequency circuit 1 according to this embodiment, when the electronic component electrically connected to the main lines 14 and 15 of the transmission line 10 is a capacitor 32, the abnormality detection unit 62 can detect whether or not any of the first via hole 316, the second via hole 317, the first metal wiring 312, and the second metal wiring 313 is broken.

[0098] (Second embodiment) Next, a high-frequency circuit and an anomaly detection method thereof according to a second embodiment of the present invention will be described with reference to Figures 7 and 8. Components similar to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted as appropriate. Similarly, operations similar to those in the first embodiment are also omitted as appropriate.

[0099] Figure 7 shows the configuration of the high-frequency circuit 2 in this embodiment.

[0100] Between the first main line 12 and the second main line 13, the base and collector of a transistor 34 are inserted in series, with the base and collector electrically connected to the main lines 12 and 13, respectively. A resistor 26 is connected in parallel between the base and collector of the transistor 34. The transistor 34 is an example of an electronic component of the high-frequency circuit 2, and the base and collector of the transistor 34 correspond to two terminals through which no DC current flows.

[0101] The main lines 12 and 13, the branch line 23 as the first branch line, the branch line 24 as the second branch line, the resistor 26, and the transistor 34 constitute the circuit 52 under inspection.

[0102] The resistance value of resistor 26 should preferably not affect the overall circuit characteristics of the high-frequency circuit 2; for example, it should be about 10 times the base-emitter resistance of transistor 34.

[0103] In this embodiment, bias terminals 41a and 42a are electrically connected to the main lines 12 and 13 via bias circuits 41 and 42, respectively. The bias terminals 41a and 42a are located on the outside of the main lines 12 and 13 that constitute the circuit 52 under inspection, and also serve as a pair of measuring terminals that are connected to the measuring device 60 when an abnormality is diagnosed.

[0104] In this embodiment, the measurement circuit 61 is connected to the bias terminals 41a and 42a when diagnosing an abnormality in the high-frequency circuit 2, and measures at least one of the following values: the resistance between the bias terminals 41a and 42a, the voltage between the bias terminals 41a and 42a, and the current flowing between the bias terminals 41a and 42a.

[0105] For example, the measurement circuit 61 applies a constant DC voltage to the circuit under test 52 via bias terminals 41a and 42a to measure the current flowing between bias terminals 41a and 42a, and calculates the resistance value between bias terminals 41a and 42a based on the measurement result.

[0106] Alternatively, the measurement circuit 61 may apply a constant DC current to the circuit 52 under test via the bias terminals 41a and 42a to measure the voltage between the bias terminals 41a and 42a, and then calculate the resistance value between the bias terminals 41a and 42a based on the measurement result.

[0107] Furthermore, the measurement circuit 61 may calculate the resistance value of the circuit under test 52 by subtracting the known resistance values ​​of the bias circuits 41 and 42 from the resistance value between the bias terminals 41a and 42a.

[0108] The abnormality detection unit 62 is configured to detect whether or not at least one type of abnormality has occurred, including a break in the main lines 12 and 13, a break in the connecting conductor described later, or a short circuit in the transistor 34, based on the measurement values ​​measured by the measurement circuit 61.

[0109] For example, if the base-collector capacitance of transistor 34 is C2 [pF] and the resistance of resistor 26 is R2 [Ω], then the normal impedance of the circuit under test 52 is 1 / {(1 / R2)+(jωC2)}, and a current corresponding to R2 flows between the bias terminals 41a and 42a.

[0110] On the other hand, if there is a break in the main lines 12, 13 or the connecting conductor, R2 is equivalent to being infinite, so the impedance of the circuit under test 52 becomes 1 / {(1 / ∞)+(jωC1)}, and no current flows between the bias terminals 41a and 42a.

[0111] Therefore, the abnormality detection unit 62 determines that there is a break in at least one location in the main lines 12, 13 and the connecting conductor when the resistance value measured by the measurement circuit 61 is equivalent to an infinite value.

[0112] If resistor 26 is not placed in parallel with the base and collector of transistor 34, it will be impossible to distinguish whether the current is not flowing between bias terminals 41a and 42a due to the DC blocking effect of transistor 34, or due to a break in the main lines 12 and 13.

[0113] Furthermore, if the original base-collector capacitance of transistor 34 is C2 [pF] and the resistance of resistor 26 placed in parallel is R2 [Ω], then if the base-collector of transistor 34 is short-circuited, C2 = ∞. In this case, the impedance of the circuit under test 52 is 1 / {(1 / R2)+(jω∞)}, and current flows between bias terminals 41a and 42a regardless of R2.

[0114] Therefore, the abnormality detection unit 62 determines that the base-collector of transistor 34 is short-circuited when the current measured by the measurement circuit 61 is not within the current range expected from the normal impedance of the circuit under inspection 52.

[0115] Figures 8(a) and 8(b) show specific configuration examples of the circuit 52 to be inspected in this embodiment. Figure 8(a) is a top view of the circuit 50 to be inspected, and Figure 8(b) is a cross-sectional view taken along line AA of Figure 8(a).

[0116] As shown in Figure 8(b), the dielectric substrate 100 consists of, for example, a lower substrate 110 and an upper substrate 120.

[0117] The lower substrate 110 is a semiconductor substrate similar to that of the first embodiment. A transistor 34 is formed on the surface side of the lower substrate 110.

[0118] The upper substrate 120, as in the first embodiment, is made of a single-layer or multi-layer material with a relatively low dielectric constant, such as BCB or SiO2. Figure 8(b) shows an example in which the upper substrate 120 consists of three dielectric layers 191, 192, and 193. Note that the upper substrate 120 is not shown in Figure 8(a).

[0119] As shown in Figure 8(b), the circuit 52 under inspection in this embodiment has a multilayer structure consisting of four layers, from the first wiring layer to the fourth wiring layer. That is, the circuit 52 under inspection is constructed by stacking multiple dielectric layers and wiring layers on the surface side of the lower substrate 110, which is a semiconductor substrate.

[0120] The first wiring layer on the surface of the dielectric layer 191 is provided with a first main line conductor 121 that constitutes part of the main line 12 and a second main line conductor 131 that constitutes part of the main line 13.

[0121] On the surface of the dielectric layer 192, a first metal wiring 321 is provided below the first main line conductor 121, and a second metal wiring 322 is provided below the second main line conductor 131.

[0122] The third wiring layer on the surface of the dielectric layer 193 is provided with a third metal wiring 325, a fourth metal wiring 326, a grounding conductor layer 327 which constitutes part of the main line 12, and a grounding conductor layer 328 which constitutes part of the main line 13.

[0123] The third metal wiring 325 is located below the first metal wiring 321, and the fourth metal wiring 326 is located below the second metal wiring 322. The grounding conductor layer 327 is located below the first main line conductor 121, and the grounding conductor layer 328 is located below the second main line conductor 131.

[0124] In the examples shown in Figures 8(a) and (b), the main lines 12 and 13 are microstrip lines with an impedance of 50Ω, and the grounding conductor layers 327 and 328 are provided as RF grounds for the main lines 12 and 13, respectively.

[0125] The fourth wiring layer on the surface of the lower substrate 110 is provided with a first branch conductor 323 that forms part of the branch line 23, a second branch conductor 324 that forms part of the branch line 24, a fifth metal wiring 329 electrically connected to the base, which is one terminal of the transistor 34, and a sixth metal wiring 330 electrically connected to the collector, which is the other terminal of the transistor 34. The emitter of the transistor 34 is grounded to a ground conductor layer (not shown).

[0126] The first branch conductor 323 and the fifth metal wiring 329 are located below the third metal wiring 325, and the second branch conductor 324 and the sixth metal wiring 330 are located below the fourth metal wiring 326.

[0127] The first main line conductor 121 and the first metal wiring 321 are electrically connected by the first via hole 331. The second main line conductor 131 and the second metal wiring 322 are electrically connected by the second via hole 332.

[0128] The first metal wiring 321 and the third metal wiring 325 are electrically connected by the third via hole 333. The second metal wiring 322 and the fourth metal wiring 326 are electrically connected by the fourth via hole 334.

[0129] The third metal wiring 325 and the fifth metal wiring 329 are electrically connected by the fifth via hole 335. The fourth metal wiring 326 and the sixth metal wiring 330 are electrically connected by the sixth via hole 336.

[0130] The first via hole 331, the second via hole 332, the third via hole 333, the fourth via hole 334, the fifth via hole 335, the sixth via hole 336, the first metal wiring 321, the second metal wiring 322, the third metal wiring 325, the fourth metal wiring 326, the fifth metal wiring 329, and the sixth metal wiring 330 constitute a connecting conductor.

[0131] The first branch conductor 323 is integrally formed with the fifth metal wiring 329 and electrically connects the base of the transistor 34 to one end of the resistor 26, which is made of thin-film metal. The second branch conductor 324 is integrally formed with the sixth metal wiring 330 and electrically connects the collector of the transistor 34 to the other end of the resistor 26.

[0132] The configuration of the first to sixth beer halls 331 to 336 is the same as the configuration of the first to third beer halls 316 to 318 in the first embodiment.

[0133] Similar to the circuit 50 under inspection in the first embodiment, the lengths of the branch lines 23 and 24 are integer multiples of approximately half the wavelength λg of the high-frequency signal transmitted through the branch lines 23 and 24, that is, integer multiples of the electrical length of 180°.

[0134] Furthermore, the transistor 35 can also be used to construct a circuit for inspection consisting of the main lines 16, 17, the first branch line, the second branch line, a resistor, and the transistor 35, similar to the circuit 52 under inspection. In this case, when diagnosing an abnormality in the high-frequency circuit 2, the measurement circuit 61 of the measurement device 60 can be connected between the bias terminals 43a and 44a, which serve as a pair of measurement terminals, to detect an abnormality in the above-mentioned circuit for inspection, including the transistor 35.

[0135] As described above, in this embodiment, the high-frequency circuit 2 has a resistor 26 connected in parallel between the base and collector of the transistor 34, and measures the resistance, voltage, or current of the circuit under test 52, which includes the parallel circuit of the transistor 34 and the resistor 26, via the bias terminals 41a and 42a.

[0136] As a result, the high-frequency circuit 2 and its abnormality detection method according to this embodiment can detect whether or not at least one type of abnormality has occurred in the circuit 52 under inspection, including a break in the main lines 12 and 13 of the transmission line 10, a break in the connecting conductor, or a short circuit of the transistor 34 as an electronic component, all in a compact configuration.

[0137] Furthermore, in the high-frequency circuit 2 according to this embodiment, the abnormality detection unit 62 can detect whether or not any of the first via hole 331, second via hole 332, third via hole 333, fourth via hole 334, fifth via hole 335, sixth via hole 336, first metal wiring 321, second metal wiring 322, third metal wiring 325, fourth metal wiring 326, fifth metal wiring 329, and sixth metal wiring 330 are broken. [Explanation of symbols]

[0138] 1,2 High-frequency circuits 10 Transmission lines 11~18 Main track 21-24 Branching tracks 25, 26 resistors 32 Capacitors 34,35 transistors 41, 42, 43, 44 Bias circuit 41a, 42a, 43a, 44a Bias terminals 50, 52 Circuits to be inspected 60 Measuring devices 61 Measurement circuit 62 Anomaly detection unit 63 Display section 100 Dielectric substrate 121,141 First main line conductor 131,151 Second main line conductor 211,323 First branch conductor 212,324 Second branch conductor 301,311 metal layer 303 Air Bridge 304,319 dielectric films 312,321 1st metal wiring 313,322 2nd metal wiring 316,331 First Beer Hall 317,332 Second Beer Hall 318,333 Third Beer Hall 325 Third metal wiring 326 4th metal wiring 329 5th metal wiring 330 6th metal wiring 334 4th Beer Hall 335 5th Beer Hall 336 6th Beer Hall

Claims

1. A high-frequency circuit (1, 2) in which a transmission line (10) for transmitting high-frequency signals is provided on a dielectric substrate (100), An electronic component (32, 34, 35) having multiple terminals connected to the main lines (12-17) of the transmission line, A resistor (25, 26) is connected in parallel between two terminals of the aforementioned electronic component that do not carry DC current, It is equipped with a pair of measuring terminals (41a, 42a, 43a, 44a) connected to the main line and positioned on both sides of the circuit under test (50, 52) including the resistor and the electronic component, and connected to a measuring device (60) when an abnormality is diagnosed, The measuring device is, A measuring circuit (61) applies a DC voltage or DC current to the circuit under test via the pair of measuring terminals and measures at least one of the following values: the resistance between the pair of measuring terminals, the voltage between the pair of measuring terminals, and the current flowing between the pair of measuring terminals. A high-frequency circuit characterized by comprising an abnormality detection unit (62) that detects whether or not at least one type of abnormality has occurred, including a break in the main line or a short circuit in the electronic component, based on the measured value measured by the measurement circuit.

2. A first branch line (21, 23) branches off from the main line and connects one of the two terminals of the electronic component to one end of the resistor, The system further includes a second branch line (22, 24) that branches off from the main line and connects the other terminal of the electronic component to the other end of the resistor, The high-frequency circuit according to claim 1, characterized in that the length of the first branch line and the second branch line from the main line to the resistor is an integer multiple of approximately 1 / 2 of the wavelength of the high-frequency signal transmitted through the first branch line and the second branch line.

3. The main line includes a first main line (14) and a second main line (15) that are capacitively coupled to each other via the electronic components. The first main line conductor of the first main line, the second main line conductor of the second main line, the first branch conductor of the first branch line, and the second branch conductor of the second branch line are provided on the surface of the dielectric substrate. The aforementioned high-frequency circuit is A metal layer (301) provided above the dielectric substrate, An air bridge (303) connecting the first main line conductor and the metal layer, The device further comprises a dielectric film (304) provided between the second main line conductor and the metal layer, The first branch conductor is integrally formed with the first main line conductor, The second branch conductor is integrally formed with the second main line conductor. The high-frequency circuit according to claim 2, characterized in that the electronic component is a capacitor (32) including the metal layer which also serves as one of the terminals, the dielectric film, and the second main line conductor which also serves as the other terminal.

4. The main line includes a first main line (14) and a second main line (15) that are capacitively coupled to each other via the electronic components. The first main line conductor of the first main line and the second main line conductor of the second main line are provided on the surface of the dielectric substrate. The aforementioned high-frequency circuit is The first metal wiring (312) provided below the first main line conductor, The second metal wiring (313) provided below the second main line conductor, A metal layer (311) provided above the first metal wiring and the second metal wiring, A dielectric film (319) is provided between the second metal wiring and the metal layer, A first via hole (316) connecting the first main line conductor and the first metal wiring, A second via hole (317) connecting the second main line conductor and the second metal wiring, The present invention further comprises a third via hole (318) connecting the first metal wiring and the metal layer, The first branch conductor of the first branch line, which is provided below the first main line conductor, is integrally formed with the first metal wiring. The second branch conductor of the second branch line, which is provided below the second main line conductor, is integrally formed with the second metal wiring. The electronic component is a capacitor (32) including the metal layer which also serves as one of the terminals, the dielectric film, and the second metal wiring which also serves as the other terminal. The high-frequency circuit according to claim 2, characterized in that the abnormality detection unit further detects whether any of the first metal wiring, the second metal wiring, the first via hole, and the second via hole are disconnected.

5. The main line includes a first main line (12) connected to one terminal of the electronic component and a second main line (13) connected to the other terminal of the electronic component. The first main line conductor of the first main line and the second main line conductor of the second main line are provided on the surface of the dielectric substrate. The aforementioned high-frequency circuit is The first metal wiring (321) provided below the first main line conductor, The second metal wiring (322) provided below the second main line conductor, A third metal wiring (325) is provided below the first metal wiring, A fourth metal wire (326) is provided below the second metal wire, A fifth metal wire (329) is provided below the third metal wire and connected to one of the terminals, A sixth metal wire (330) is provided below the fourth metal wire and connected to the other terminal, The device further comprises a plurality of via holes (331-336) that connect the first main line conductor to the first metal wiring, the third metal wiring, and the fifth metal wiring, and that connect the second main line conductor to the second metal wiring, the fourth metal wiring, and the sixth metal wiring, The first branch conductor of the first branch line, which is provided below the third metal wiring, is integrally formed with the fifth metal wiring. The second branch conductor of the second branch line, which is located below the fourth metal wiring, is integrally formed with the sixth metal wiring. The aforementioned electronic component is an emitter-common transistor (34, 35) in which one terminal is the base and the other terminal is the collector. The high-frequency circuit according to claim 2, characterized in that the abnormality detection unit further detects whether any of the first metal wiring, the second metal wiring, the third metal wiring, the fourth metal wiring, the fifth metal wiring, the sixth metal wiring, or the plurality of via holes are disconnected.

6. A high-frequency circuit (1, 2) in which a transmission line (10) for transmitting high-frequency signals is provided on a dielectric substrate (100), An electronic component (32, 34, 35) having multiple terminals connected to the main lines (12-17) of the transmission line, A resistor (25, 26) is connected in parallel between two terminals of the aforementioned electronic component that do not carry DC current, An abnormality detection method for a high-frequency circuit, comprising: a pair of measuring terminals (41a, 42a, 43a, 44a) connected to the main line and positioned on both sides of the circuits to be inspected (50, 52) including the resistor and the electronic component, and connected to a measuring device (60) when an abnormality is diagnosed, The measuring device is, A DC voltage or DC current is applied to the circuit under test via the pair of measuring terminals, and at least one of the following values ​​is measured by the measuring circuit (61): the resistance between the pair of measuring terminals, the voltage between the pair of measuring terminals, and the current flowing between the pair of measuring terminals. An abnormality detection method characterized in that, based on the measured value measured by the measurement circuit, an abnormality detection unit (62) detects whether or not at least one type of abnormality has occurred, including a break in the main line or a short circuit in the electronic component.

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