JPH09260945A - Microwave and millimeter wave oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave/millimeter wave oscillator with which a phase noise is suppressed to a low level and an oscillation frequency can be highly stabilized by connecting a dielectric resonator to both a connection line and an output circuit. SOLUTION: A resonance circuit 4 at a gate has a connection line 8 and a dielectric resonator 9 is mounted so as to be connected to the connection line 8 and to be connected to an output circuit 6 as well. The gate on a GaAs substrate 12 is used as an active oscillator 1 and a varactor 3, and the resonance circuit 4 is formed by providing a short stub 2 for serial feedback, varactor 3 and connection line 8. Besides, a monolythic semiconductor integrated circuit having the output circuit 6 provided with an output matching circuit 5 using the short stub is formed. A dielectric resonance circuit 9 is composed of the ceramic of BaO3 and arranged at a proximate position without being overlapped with the connection line 8 and the transmission line of the output circuit 6. Namely, rough connection more becomes the low phase noise. As the position of the dielectric resonator 9, the position of a simple transmission line on the following stage of the output matching circuit 5 is satisfactory.

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 oscillator for stabilizing oscillation by using a dielectric resonator.

[0002]

2. Description of the Related Art Conventionally, microwave and millimeter wave oscillators and the like use 3-terminal active elements such as FETs and bipolar transistors, and a series feedback circuit, a resonance circuit and an output matching circuit are connected to the 3 terminals, respectively. A series feedback type configuration is often adopted. A specific circuit example is shown in FIG.
The configuration shown in FIG.

That is, an FET (Field E
A series feedback circuit 22 for generating a negative resistance is connected to the source of the FET 21, a resonance circuit 23 is connected to the gate of the FET 21, and an output matching circuit 24 is connected to the drain of the FET 21.

A varactor 25 is connected to the resonance circuit 23 for controlling the frequency, and a dielectric resonator 27 is connected to the transmission line 26 for stabilizing the oscillation frequency and reducing noise. Be loaded. Vc is the varactor 25
Is the control voltage of.

[0005]

However, in the case of the above series feedback oscillator, if the series resistance of the varactor is large and the Q is not too high, the oscillation frequency cannot be sufficiently stabilized even if the dielectric resonator is used. Therefore, there has been a problem that the phase noise cannot be suppressed low.

The present invention solves the drawbacks of the series feedback type microwave / millimeter wave oscillator loaded with such a dielectric resonator.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has a transistor as an active element and a resonance including a series feedback circuit and a coupling line with a dielectric resonator at each of three terminals of the transistor. A series feedback microwave / millimeter wave oscillator having the dielectric resonator to which an output circuit including a circuit and an output matching circuit is connected, wherein the dielectric resonator is provided in both the coupling line and the output circuit. A microwave / millimeter wave oscillator to be coupled is provided.

The present invention also provides a microwave / millimeter-wave oscillator in which the above-mentioned resonant circuit comprises a varactor as a part of a circuit element.

Further, the present invention provides a microwave / millimeter wave oscillator configured such that the degree of coupling with the dielectric resonator is coarser in the output circuit than in the coupled line.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a microwave / millimeter wave oscillator according to an embodiment of the present invention.

In the figure, an active element 1 for oscillation is NA
lGaAs / InGaAs heterojunction FET, F
A short stub 2 as a series feedback circuit for generating a negative resistance is connected to the source of ET, a resonance circuit 4 including a varactor 3 is connected to the gate of the FET, and an output circuit 6 including an output matching circuit 5 is connected to the drain of the FET. It

Here, the varactor 3 has the same N as the active element 1.
-AlGaAs / InGaAs Heterojunction FET gate capacitance is used, but in order to have a linear frequency characteristic and reduce series resistance, as disclosed in Japanese Patent Publication No. 7-73636, the drain of the heterojunction FET is used. Is short-circuited by RF (Radio Frequency) with the capacitor 7, and the DC bias voltage Vdv can be applied to the drain.

The gate resonance circuit 4 is further provided with a coupling line 8, and the dielectric resonator 9 is loaded so as to be coupled to the coupling line 8 and also to the output circuit 6. Incidentally, 10 is a bypass capacitor for the bias line, 11
Is a DC blocking capacitor.

On the other hand, the series resistance of the varactor 3 is reduced by applying a DC voltage to the drain, but it is still several Ω with respect to the gate capacitance of 0.1 pF. Therefore, the Q of the varactor 3 is about 10 at 60 GHz. It is as small as the following and the Q of the entire resonance circuit 4 is lowered.

Therefore, even if the dielectric resonator 9 is coupled only to the coupling line 8 of the resonance circuit 4 as in the conventional case, the suppression of the phase noise is not sufficient. Therefore, in the present embodiment, the dielectric resonator 9 is used not only for the coupling line 8 of the resonance circuit 4 but also for the output circuit 6
In addition, it is intended to stabilize the oscillation frequency and suppress the phase noise.

[0016]

EXAMPLES Specific examples of the first embodiment of the present invention will be described below. FIG. 2 is a perspective view of a main part of the first embodiment, which is a 30 GHz band monolithic voltage controlled oscillator.

First, 0.15 μm on the GaAs substrate 12
An output including a gate AlGaAs / InGaAs heterojunction FET as an oscillation active element 1 and a varactor 3, a series feedback short stub 2, a resonant circuit 4 including a varactor 3 and a coupling line 8, and an output matching circuit 5 using a short stub. A monolithic semiconductor integrated circuit (hereinafter referred to as MMIC) having the circuit 6 was manufactured.

Here, the thickness of the GaAs substrate 12 is 0.0
4 mm, the thickness of the Au-plated radiator 6 is 0.04 mm. Then, this MMIC chip is fixed to the bottom of an Au plating case (not shown) by using solder.

On the other hand, the dielectric resonator 9 is composed of Ba (Mg, T
a) A cylindrical type made of O ₃ ceramic with a diameter of 2.2 mm and a height of 1.4 mm. As shown in FIG. 2, the end of the dielectric resonator 9 is coupled to the coupling line 8 and the output circuit 6. An oscillator was manufactured by installing and fixing the dielectric resonator 9.

The phase noise of the oscillator in this embodiment is
At a frequency 100 kHz away from the peak of the oscillation frequency, it becomes -96 dBc / Hz, which is 6 dB better than the oscillator in which the dielectric resonator is coupled only to the coupling line of the conventional resonance circuit.

In this embodiment, as shown in FIG. 2, the dielectric resonator 9 does not overlap the transmission line of the output circuit 6 and is arranged in a very close position, that is, it is better to use the coarse coupling. The result is low phase noise. Further, as for the coupling position of the dielectric resonator 9 in the output circuit 6, a good result was obtained in which the position of the simple transmission line at the latter stage of the output matching circuit 5 was good.

Next, a second example of this embodiment will be shown.
FIG. 3 is a perspective view of an essential part showing a second embodiment, which is 60 GHz.
It is a monolithic voltage controlled oscillator of the band. The circuit configuration of this embodiment is similar to that of the first embodiment, but the output circuit 6 is configured to be parallel to the coupling line 8 of the resonance circuit 4.

The dielectric resonator 9 has a diameter of 1.3 mm,
This dielectric resonator 9 has a cylindrical shape with a height of 0.55 mm.
Are arranged so as to straddle the coupling line 8 and be coupled also to the output circuit 6. That is, the dielectric resonator 9 is connected to the coupled line 8
It is tightly coupled with.

In this state, the phase noise is 10 dB or more and the fluctuation of the oscillation frequency with respect to the change of the environmental temperature is improved to a fraction of that in the conventional case where the dielectric resonator 9 is not coupled to the output circuit 6. It was

As in the first embodiment, the reason why better characteristics can be obtained when the dielectric resonator 9 is tightly coupled with the coupling line 8 of the resonance circuit 4 than the output circuit 6 is that the dielectric resonator 9 is obtained. Since the resonance circuit 4 including 9 determines the oscillation frequency,
It is considered preferable that the dielectric resonator 9 is loosely coupled to the output circuit 6 so as not to affect this.

Further, comparing the case where the dielectric resonator 9 is coupled to the transmission line after the output matching circuit 5 of the output circuit 6 and the case where it is coupled to the output matching circuit 5, both the phase noise and the oscillation output are compared. Was better. This is because the oscillation condition is determined including the output matching circuit 5, and it is considered that it is better to couple the dielectric resonator 9 to a simple transmission line of the output circuit 6 that does not affect this.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and may be implemented in any way unless the configuration described in the claims is changed. it can. For example, in each of the above embodiments, the microstrip line is used as the coupling line with the dielectric resonator, but the present invention is not limited to this, and various types such as a coplanar line can be used.

Also, as the circuit configuration of the oscillator, the case where the feedback element is connected to the source of the FET, the resonance circuit is connected to the gate, and the output circuit is connected to the drain has been described, but the present invention is not limited to this. Can be applied to a series-feedback type oscillation circuit including an arbitrary combination in which these are separately connected to the three terminals of the transistor.

[0029]

As described above, in the microwave / millimeter wave oscillator according to the present invention, the phase noise can be suppressed to a low level in the structure of the voltage controlled oscillator loaded with the dielectric resonator, and the oscillation frequency can be suppressed. It is possible to achieve high stability, and it is possible to greatly contribute to the expansion of application to communication systems.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a microwave / millimeter wave oscillator according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a main part of a microwave / millimeter wave oscillator according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a main part of a microwave / millimeter wave oscillator according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a conventional microwave / millimeter wave oscillator.

[Explanation of symbols]

 1 Oscillation Active Element 2 Short Stub for Feedback 3 Varactor 4 Resonance Circuit 5 Output Matching Circuit 6 Output Circuit 7, 11 Capacitor 8 Coupling Line 9 Dielectric Resonator 10 Bypass Capacitor 12 GaAs Substrate 13 Heat Dissipator

Claims (3)

[Claims] 1. A dielectric resonance in which a transistor is an active element, and a series feedback circuit, a resonance circuit including a coupling line with a dielectric resonator, and an output circuit including an output matching circuit are connected to three terminals of the transistor, respectively. A microwave / millimeter wave oscillator of series feedback type having a resonator, wherein the dielectric resonator is coupled to both the coupling line and the output circuit. 2. The microwave / millimeter wave oscillator according to claim 1, wherein the resonance circuit comprises a varactor as a part of a circuit element. 3. The degree of coupling with the dielectric resonator is configured to be coarser in the output circuit than in the coupled line, according to any one of claims 1 and 2. Microwave / millimeter wave oscillator.