JPH10224107A - Microwave integrating circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a microwave integrating circuit by connecting a stub, whose tip part at least is provided proximately to a ground conductor so as to operate by a second frequency different from a first frequency. SOLUTION: An electrode 2 is formed linearly on a semiconductor substrate 1 to constitute a main transmission line M2. In addition, an electrode 3 is formed to be connected with the electrode 2 at a prescribed position, to constitute a stub M3 of an open tip connected with the main transmission line M2. At this microwave integrated circuit with low-pass characteristic, at the time of connecting the tip of the stub M3 of the open tip (the tip of the electrode 3) and the ground conductor E1 through a metallic conductor which is, e.g. a wire, the stub M3 becomes the stub of a short-circuited tip. Consequently, the constituted microwave integrated circuit acts as a high-pass filter without changing an electrode pattern by only connecting the tip of the stub M3 with the conductor E1. Thus, the integrated circuit is operated by a second frequency which is different from a first frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave / millimeter-wave integrated circuit (hereinafter simply referred to as a microwave integrated circuit) using a semiconductor substrate. The present invention relates to a microwave integrated circuit capable of changing circuit characteristics depending on the presence or absence of connection.

[0002]

2. Description of the Related Art A microwave or millimeter-wave band microwave integrated circuit formed on a semiconductor substrate or the like has a unique transmission line that is optimally set according to each design frequency, design parameter of a semiconductor element, circuit configuration, and the like. And an electrode pattern. This is because the length of the metal wiring that constitutes the circuit is about the same as the wavelength of the radio wave that propagates, so the impedance of the circuit changes due to the change in the length of the transmission line and the shape of the electrode pattern This is because the frequency at which a predetermined characteristic is obtained changes. For this reason, the conventional microwave integrated circuit is manufactured by individually designing a pattern when the frequency used is different. In addition, microwaves and millimeter waves have become relatively easy to use due to recent technological development, and application of microwaves and millimeter waves (hereinafter referred to as microwaves) to various devices has been actively studied in various countries. It is being advanced.

[0003]

However, in a microwave or the like, the frequency (frequency band) that can be used for each device is, for example, the frequency assigned to an on-vehicle collision prevention radar is 60 GHz in Japan. On the other hand, the U.S. and Europe are assigned by the government separately for each country so that the 77 GHz band is used, and it is necessary to design and manufacture different microwave integrated circuits for each device and each country. there were. For this reason, the microwave integrated circuit also needs to carry out research and development at each of these different frequencies, so that many development periods and development personnel are required, and the development cost is high. In addition, a microwave integrated circuit is prototyped at each frequency, and a separate electrode pattern is formed for each frequency band to manufacture the microwave integrated circuit. Was.

An object of the present invention is to solve the above problems and to provide a microwave integrated circuit that can be developed at low cost and can be manufactured at low cost.

[0005]

According to the present invention, in order to achieve the above-mentioned object, the present invention is constituted by using the same electrode pattern and connecting the electrode pattern at a predetermined position to a ground conductor by wire bonding or the like. This is a microwave integrated circuit that can change the operating frequency depending on whether it is or not. That is, the present invention includes a microwave integrated circuit that operates at a predetermined first frequency, including a stub having an open end formed of a transmission line formed of electrodes of a predetermined shape formed on a semiconductor substrate. Wherein at least a tip portion of the stub is provided close to a ground conductor formed on a dielectric substrate, and an electrode forming the stub is connected to the ground conductor at a portion close to the ground conductor. Thus, it is possible to operate at a second frequency different from the first frequency.

In the present invention, a first portion of a predetermined length from the tip of the electrode constituting the stub is formed close to and along the ground conductor, and a predetermined portion of the first portion is formed. By connecting to the ground conductor at a position, the second frequency can be set to a desired frequency.

Furthermore, in the present invention, it is preferable that a capacitor for preventing a direct current from flowing between the electrode and the ground conductor is formed at a part of the electrode constituting the stub.

In the present invention, the electrode constituting the stub and the ground conductor may be grounded via a capacitor.

According to another aspect of the present invention, there is provided a microwave integrated circuit including: a transistor having first, second, and third terminals; and a feedback transmission line connected to the second terminal. The stub having an open end is the first stub.
A microwave oscillation circuit that is connected to a terminal of the stub and oscillates at the first frequency, and oscillates at the second frequency by connecting an electrode constituting the stub and the ground electrode. It is characterized by the following.

Further, in the microwave integrated circuit, the electrode constituting the stub and the ground conductor are connected via a varactor diode, so that the second frequency can be changed.

A microwave integrated circuit according to another aspect of the present invention has first, second, and third terminals and has a second terminal.
A transistor whose terminal is grounded, an input matching circuit connected to the first terminal, and an output matching circuit connected to the third terminal. The input matching circuit and the output matching circuit A microwave amplifier circuit for amplifying a microwave signal in a first frequency range including the first frequency including the stub having the open end,
When each of the stubs is connected to a ground conductor, the microwave signal is amplified in a second frequency range including the second frequency.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 shows a low-pass filter which is a microwave integrated circuit according to the first embodiment of the present invention. The microwave integrated circuit shown in FIG.
(Eg, gold, aluminum, etc.) are formed to form a main transmission line M2 through which signals propagate. The electrode 3 having a predetermined length is formed so as to be connected to the electrode 2 at a predetermined position, and a stub M having an open end connected to the main transmission line 2.
3 are configured. Here, in the microwave circuit according to the first embodiment, the tip of the electrode 3 is close to the ground conductor E1 provided on the semiconductor substrate, for example, and the ground conductor E1
And is formed so as not to conduct. In FIG. 1, reference numerals of the main transmission line M2 and the stub M3 are shown in parentheses behind the electrodes 2 and 3. In the microwave integrated circuit of FIG. 1 configured as described above, the impedance when the open-ended stub M3 having one open end is viewed from the connection point with the main transmission line M2 is such that the length of the open-end stub 3 is small. ,
When the signal is sufficiently long with respect to the wavelength of the signal transmitted through the main transmission line M2, it becomes infinite. As a result, the microwave circuit constituted by the pattern shown in FIG. 1 becomes a low-pass filter having the characteristics shown in FIG.

In the microwave integrated circuit of FIG. 1 configured as described above and having a low-pass characteristic, as shown in FIG. 2, the tip of the open stub M3 (the tip of the electrode 3) and the ground conductor E1 are connected to each other. Are connected by, for example, a conductive metal 4 which is a wire, the stub M3 becomes a stub having a short-circuited end. In the state where the tip of the stub M3 is short-circuited, the stub M3
Is seen from the connection point with the main transmission line M2, the impedance becomes 0 when the length of the stub M3 is sufficiently long with respect to the wavelength of the signal transmitted through the main transmission line M2. As a result, in the microwave integrated circuit constituted by the pattern shown in FIG. 1, only the tip of the stub M3 is connected to the ground conductor E1, and the electrode pattern is not changed.
It can be operated as a high-pass filter having the characteristics shown in FIG.

In the semiconductor process, the main transmission line M2 and the stub M3 are usually used from the viewpoint of improving the reliability of the device.
Although a protective film is formed thereon with a silicon nitride film or the like, in the first embodiment, the protective film is not formed at a portion where a wire or the like is connected. Alternatively, the protective film itself may not be used.

In the microwave integrated circuit, a ground conductor is usually formed on the lower surface of the semiconductor substrate 1. In the present invention, when the electrode 3 forming the stub M3 is connected to the ground conductor by, for example, wire bonding, the ground conductor is grounded. The conductor E1 is preferably formed on the upper surface. FIG. 3 shows a modification of the first embodiment in which a ground conductor pad E5 for wire bonding is formed on the upper surface of the semiconductor substrate 1 by using a via hole 6 to a ground conductor formed on the lower surface. . Even with the configuration described above, the same operation as in the first embodiment is performed and the same effect is obtained.

In the first embodiment described above, the electrode 3 constituting the stub M3 is directly connected to the ground conductor E1, but the present invention is not limited to this, and as shown in FIG. May be connected to the ground conductor E1 via a capacitor such as a capacitor formed in the above. In FIG. 4, what is indicated by the reference numeral 7 is a capacitor formed of a chip capacitor, and one electrode of the chip capacitor has a stub M via a conductive metal 4.
3 and the other electrode of the chip capacitor is connected to the ground conductor E1 (not shown). With this configuration, the stub M3 can be grounded for a high-frequency signal, and can be opened DC.

In the first embodiment, in order to prevent DC current from flowing through the electrode 3 constituting the stub M3,
As shown in FIG. 5, an MIM capacitor (Metal-Insulator-Metal capacitor) that can be easily formed in a semiconductor manufacturing process may be formed in the middle of the electrode 3. As shown in FIG.
Even if is inserted in the middle of the stub M3 having the open end, if the end is in the open state, the filter characteristic is equivalent to the pattern of the first embodiment shown in FIG. When the stub M3 is short-circuited at the tip, as shown in FIG. 5 or FIG. 6, the tip of the stub M3 having the open tip can be directly connected to the ground conductor pad E5 or the ground conductor E1 using the conductive metal 4 as it is. Good. Even with the configuration described above, the same operation as in the first embodiment is performed and the same effect is obtained.

Embodiment 2 FIG. FIG. 8 is a block diagram showing a configuration of a microwave / millimeter wave band oscillator according to the second embodiment of the present invention. The microwave / millimeter wave oscillator shown in FIG. 8 includes a transistor 18 having excellent operation characteristics in a microwave / millimeter wave band such as a field effect transistor on a semiconductor substrate and a predetermined parameter connected to each terminal of the transistor. Are connected and configured as follows. That is, an open-ended stub M15 forming a resonance circuit in the oscillator is connected to the gate terminal of the transistor 18, and the gate-side bias terminal 10 is connected to the gate terminal via the transmission line 16 forming the gate bias circuit. Is done. The drain terminal of the transistor 18 is connected to a drain-side bias terminal 11 via a transmission line 17 forming a drain bias circuit, and the drain terminal is connected to an oscillator via a transmission line 13 forming an output matching circuit. Output terminal 12 is connected. The source terminal of the transistor 18 is grounded via the transmission line 14 to form a feedback circuit.

In the microwave / millimeter-wave band oscillator according to the second embodiment configured as described above, the oscillation frequency is set as follows. That is, assuming that the reflection coefficient looking at the stub M15 forming the resonance circuit from the point indicated by the symbol A in the drawing is Γr and the reflection coefficient looking at the transistor 18 is Γin, the oscillation condition is given by the following equation (1). ) And equation (2).

[0020]

[Equation 1] | Γr |> 1 / | Γin |… (1)

[Expression 2] Ang│Γr│ = Ang│Γin│ (2)

The microwave / millimeter-wave band oscillator according to the second embodiment oscillates and operates at a frequency satisfying the conditions represented by the equations (1) and (2). A specific design procedure is as follows, for example. Here, the design procedure is such that the MIM capacitor 8 is connected to the stub M15 as shown in FIG.
It is an example in the case of including. (1) The length and width of the strip conductor forming the transmission line 14 connected to the source terminal of the transistor 18 are set to be different from the first oscillation frequency f1 and the second oscillation frequency f1.
At a frequency intermediate to the oscillation frequency f2, the reciprocal (absolute value) of the impedance when the transistor 18 is viewed from the point A.
Is minimized, and the first oscillation frequency f1 and the second oscillation frequency f2 are set so as to satisfy Expression (1). (2) When the tip of the stub M15 is opened, the length and the width of the strip conductor forming the stub M15 are determined so that the impedance when the stub M15 is viewed from the point A satisfies the expression (2) at the oscillation frequency f1. Set. (3) When the tip of the stub M15 is short-circuited, the length and width of the strip conductor constituting the stub M15 and the MIM capacitor so that the impedance when the stub M15 is viewed from the point A at the oscillation frequency f2 satisfies the expression (2). 8 and the area of the bonding pad electrode 5 are set. In this setting, a conductive metal 4 such as a bonding wire is used.
Also consider the length.

In the oscillator in which each parameter is set as described above, it is the stub M15 constituting the resonance circuit that mainly determines various characteristics such as the frequency of the oscillator and the oscillation output. This resonance circuit may be constituted by an inductor, a capacitance, or the like, but in a general microwave / millimeter wave oscillator, this resonance circuit is formed by a stub having an open end or a short-circuit stub such as a microstrip line. In this case, the frequency that satisfies the above equations (1) and (2) can be changed between the case of using the stub having the open end and the case of using the stub having the short end.
In the second embodiment, the oscillation frequency is changed by using this principle when the tip is opened and when the tip is short-circuited.

FIG. 9 shows a case where the tip of the stub M15, which is a resonance circuit, is short-circuited in the microwave / millimeter-wave oscillator according to the second embodiment. In FIG. 9, stub M1
Reference numeral 5 denotes a MIM capacitor 8, the tip of which is connected to the wire connection pad 5 by the conductive metal 4 and is electrically connected to the ground conductor formed on the lower surface of the semiconductor substrate 1 via the via hole 6. . That is, the stub M15 shown in FIG. FIG. 11 shows the result of calculating the above conditional expression using the stub M15 having the short-circuited tip as a resonance circuit. As is clear from the graph of FIG.
It can be seen that short-circuiting the tip of the stub M15 causes oscillation at the frequency f1. When the wire 4 of the stub M15 having the short-circuited tip is removed, the tip of the stub M15 is electrically opened. In this case, the result calculated from the conditional expressions of Expressions (1) and (2) is shown in FIG.
Shown in As is clear from FIG. 12, in this state, oscillation occurs at a frequency f2 different from the above-mentioned frequency f1.

The microwave / millimeter-wave oscillator according to the second embodiment configured as described above can be used without changing the pattern of the microwave circuit created by the semiconductor manufacturing process.
In the wire bonding step in the final assembly step, oscillation can be performed at different frequencies depending on whether or not the electrode 15 constituting the stub M15 and the ground conductor are connected.

In the second embodiment, the tip of the stub M15 is directly connected to the ground conductor.
As shown in FIG. 0, the tip of the stub M15 may be configured to be grounded via the varactor diode 20. In this case, it is possible to oscillate at the frequency f1 when the conductive metal 4 is not connected, and to connect to the varactor diode 20 using the conductive metal 4 as shown in the figure.
In addition, oscillation can be performed at a frequency f3 different from the frequency f2, and the oscillation frequency f3 can be changed by changing the voltage applied to the diode.

Embodiment 3 FIG. FIG. 13 is a block diagram illustrating the configuration of the microwave amplification circuit according to the third embodiment of the present invention. The microwave amplification circuit includes, for example, a transistor 40 including a field-effect transistor, an input matching circuit connected to a gate terminal of the transistor 40, and an output matching circuit connected to a drain terminal of the transistor 40. Here, the input matching circuit is connected to the input terminal 32
And the transmission line 27 connected in series between the gate of the transistor 40 and the transmission line 28 connected between the connection point of the transmission line 27 and the transmission line 26 and the terminal 33. The output matching circuit is connected to the output terminal 35
Transmission line 29 and transmission line 30 connected in series between the transmission line 29 and the drain terminal of transistor 40, and transmission line 31 connected between a connection point between transmission line 29 and transmission line 30 and terminal 34. Become. In the microwave amplifier circuit according to the third embodiment, a terminal 37 that is grounded via a capacitor 39 is provided near the terminal 33.
Terminal 3 which is grounded via capacitor 38 in the vicinity of
6 are provided. Here, the transmission line 28 and the transmission line 3
Numeral 1 is a stub having an open end formed by an electrode formed on the semiconductor substrate and having an end separated from a ground conductor.
And the transmission line 31. The terminals 37 and 38 are terminal electrodes to which wires and the like can be connected. In FIG. 13, a bias circuit for driving the transistor 40 is omitted.

In the microwave / millimeter wave amplifier circuit of the third embodiment configured as described above, when both the transmission line 28 and the transmission line 31 are open, each transmission line is matched so as to match at the frequency f1. The length and width are set, and the transmission line 28 and the transmission line 31 are respectively connected to the capacitor 3.
The length and width of each transmission line are set so as to match at frequency f2 when grounded via 9, 38. FIG.
13 shows the amplification characteristics when the transmission line 28 and the transmission line 31 are both open in the microwave / millimeter wave amplifier circuit of FIG. 13, and FIG. 19 shows the amplification characteristics of the microwave / millimeter wave amplifier circuit of FIG. The amplification characteristic when the transmission line 28 and the transmission line 31 are both grounded via the capacitors 39 and 38 is shown.

In the microwave / millimeter-wave amplifier circuit of the third embodiment configured as described above, the length of each transmission line constituting the input matching circuit and the output matching circuit,
8 and the length and width of the transmission line 31 are changed to obtain desired frequency characteristics. In the present invention, in particular, the terminals 33 and 37 are connected in this input matching circuit, and the terminals 34 and 36 are connected in the output matching circuit so that matching states can be realized at different frequencies. This makes it possible to obtain amplification characteristics in different bands by connecting with a wire or the like after forming the same pattern through the same semiconductor process step.

Modified example. In the first, second, and third embodiments, the tip of the electrode constituting the stub M3 is connected to the ground conductor E1 by performing wire bonding using a wire as the conductive metal 4. However, as shown in FIG. 14, the connection may be made by using an air bridge wiring 21 which can be easily formed by using a semiconductor manufacturing process. As shown in FIG. 15, the air bridge wiring 21 can be easily removed in the assembly process, so that it can be applied to the first, second, and third embodiments of the present invention.

In the first, second, and third embodiments,
The stub having the open end may be configured as shown in FIG. The stub M22 shown in FIG. 16 forms the electrode 22 constituting the stub M22 such that a portion C separated by a predetermined length (for example, 波長 wavelength at the operating frequency) from the tip is close to the chip capacitor 7. In this portion, connection to the chip capacitor 7 is enabled by the wire 4. In the microwave circuit, the voltage amplitude becomes maximum and the impedance becomes infinite at the open end B (so-called antinode of the wave),
A short circuit state occurs in the microwave band at a distance of 1/4 wavelength from the open end B, and a ground state can be formed at a desired frequency by connecting the wire 4 and a chip capacitor at this point. . At this time, by grounding using a conductive metal 4 at a desired １ ／ wavelength at an arbitrary frequency from the open end B, grounding at an arbitrary frequency can be flexibly realized in the assembly process. The configuration can be applied to any of the first, second, and third embodiments. FIG. 17 shows a modification of FIG. 16 as an equivalent circuit. The capacitor 26 of FIG.
17, the transmission line 25 in FIG. 17 corresponds to a portion of a quarter wavelength from the tip B of the transmission line 22 in FIG. 16, and the transmission line 23 in FIG. 17 corresponds to the transmission line 22 in FIG. Corresponding to the rest of Further, FIG.
In the example of No. 6, the transmission line 22 may be grounded at any point of a 波長 wavelength portion from the tip B.

[0031]

As is apparent from the above description, the microwave integrated circuit of the present invention includes the stub having at least the tip portion provided near the ground conductor, and connects the stub to the ground conductor. By doing so, it is possible to operate at a second frequency different from the first frequency, so that microwave circuits operating at different frequencies can be configured with the same pattern. Thus, a microwave integrated circuit can be manufactured at low development cost and at low cost.

Further, in the present invention, of the electrodes constituting the stub, a first portion having a predetermined length from the tip is formed close to and along the ground conductor, and a predetermined portion of the first portion is formed. By connecting to the ground conductor at a position, the stub can be grounded at an arbitrary position, and the second frequency can be freely set to a desired frequency.

Further, in the present invention, a capacitor for preventing a direct current from flowing between the electrode and the ground conductor is formed in a part of the electrode constituting the stub, so that the capacitor is used as a stub of a bias circuit. be able to.

In the present invention, the stub and the ground conductor are grounded via a capacitor, so that the stub can be used as a stub of a bias circuit.

Further, the microwave integrated circuit, which is a microwave oscillator according to one aspect of the present invention, can oscillate at the first frequency by opening the tip of the stub, and can form an electrode constituting the stub. By connecting the ground electrode and the ground electrode, oscillation can be performed at the second frequency, so that two types of oscillators can be created with the same pattern.

Further, in the microwave integrated circuit, since the electrode constituting the stub and the ground conductor are connected via the varactor diode, the resonance frequency of the resonance circuit of the oscillator can be changed, The frequency can be changed.

In the microwave integrated circuit, which is a microwave amplifier circuit according to another aspect of the present invention, the input matching circuit and the output matching circuit each include the stub, so that the two different types of stubs are used in the same pattern. The amplification operation can be performed in one frequency band.

[Brief description of the drawings]

FIG. 1 is a plan view showing a microwave integrated circuit according to a first embodiment of the present invention.

FIG. 2 is a plan view of the microwave integrated circuit of FIG. 1, in which a tip of a stub M3 is grounded.

FIG. 3 is a plan view showing a modification of the first embodiment in FIG. 1;

FIG. 4 is a plan view showing a modification of the first embodiment shown in FIG. 1 which is different from FIG. 3;

FIG. 5 is a view of FIG. 1 when an MIM capacitor is formed on the stub M3 of FIG. 1;

6 is a diagram in which the tip of a stub M3 in FIG. 5 is grounded by a conductive metal 4. FIG.

FIG. 7A is a graph showing transmission characteristics when the tip of a stub M3 is short-circuited in the microwave integrated circuit of FIG. 1, and FIG. 7B is a graph showing a stub in the microwave integrated circuit of FIG. It is a graph which shows the passage characteristic at the time of opening the tip of M3.

FIG. 8 is a block diagram illustrating a configuration of a microwave / millimeter-wave band oscillator according to a second embodiment of the present invention.

FIG. 9 is a view of FIG. 5 when the tip of the stub M15 is grounded in the second embodiment.

FIG. 10 is a diagram showing a state in which a tip end of a stub M15 is grounded via a varactor diode 20 in the second embodiment.

FIG. 11 is a graph showing a simulation result when the tip of a stub M15 is grounded in the microwave / millimeter wave band oscillator according to the second embodiment.

FIG. 12 is a graph showing a simulation result when the tip of a stub M15 is grounded in the microwave / millimeter-wave band oscillator according to the second embodiment.

FIG. 13 is a block diagram illustrating a configuration of a microwave amplification circuit according to a third embodiment of the present invention.

FIG. 14 shows an air bridge wiring 2 connecting a stub and a ground conductor.
It is a figure which shows what was connected by 1 typically.

FIG. 15 is a diagram schematically showing a state in which the air bridge wiring 21 of FIG. 14 is removed.

FIG. 16 is a view showing another modified example according to the present invention.

FIG. 17 is a diagram showing an equivalent circuit of FIG. 16;

18 is a graph showing amplification characteristics when the transmission line 28 and the transmission line 31 are both open in the microwave / millimeter wave amplifier circuit of FIG.

FIG. 19 is a graph showing amplification characteristics when the transmission line 28 and the transmission line 31 are grounded via capacitors 39 and 38 in the microwave / millimeter wave amplification circuit of FIG.

[Explanation of symbols]

1 semiconductor substrate, 2, 3, 22 electrodes, M2, 26, 2
7, 28, 29, 30, 31 transmission line, M3, M1
5, M22 stub, 4 conductive metal, E5 ground conductor pad, 6 via hole, 7, 38, 39 capacitor, 8 MIM capacitor, 10 gate side bias terminal, 11 drain side bias terminal, 12 oscillator output terminal, 13, 14, 16, 17 transmission line, 18, 40
Transistor, 20 varactor diode, 21 air bridge wiring,

Claims (7)

[Claims] 1. A microwave integrated circuit that operates at a predetermined first frequency and includes a stub having an open end formed by a transmission line formed of electrodes having a predetermined shape and formed on a semiconductor substrate. At least a tip of the stub is provided in proximity to a ground conductor formed on the dielectric substrate, and an electrode forming the stub is connected to the ground conductor at a portion close to the ground conductor. A microwave integrated circuit characterized in that it can be operated at a second frequency different from the first frequency. 2. A first portion having a predetermined length from a tip of an electrode constituting the stub is formed close to and along the ground conductor, and the ground is formed at a predetermined position of the first portion. 2. The microwave integrated circuit according to claim 1, wherein the second frequency can be set to a desired frequency by being connected to a conductor. 3. The microwave integrated circuit according to claim 1, wherein a capacitor for preventing a direct current from flowing between the electrode and the ground conductor is formed in a part of the electrode constituting the stub. 4. The microwave integrated circuit according to claim 1, wherein an electrode constituting said stub and a ground conductor are grounded via a capacitor. 5. The microwave integrated circuit includes first and second microwave integrated circuits.
And a transistor having three terminals, and the second
And a feedback transmission line connected to a terminal of the stub, the stub having an open end connected to the first terminal and oscillating at the first frequency. The microwave integrated circuit according to any one of claims 1 to 4, wherein an oscillation at the second frequency is enabled by connecting an electrode constituting the first electrode and the ground electrode. 6. The microwave integrated circuit according to claim 5, wherein the electrode constituting the stub and the ground conductor are connected via a varactor diode, and the second frequency can be changed. 7. The microwave integrated circuit includes first and second microwave integrated circuits.
A transistor having a third terminal and the second terminal grounded, an input matching circuit connected to the first terminal, and an output matching circuit connected to the third terminal. A microwave amplifying circuit for amplifying a microwave signal in a first frequency range including the first frequency including the stub having an open end in each of the input matching circuit and the output matching circuit. 5. The microwave integrated circuit according to claim 1, wherein when each of said stubs is connected to a ground conductor, a microwave signal is amplified in a second frequency range including said second frequency. .