JPH01125006A - Microwave oscillator - Google Patents

Abstract

PURPOSE:To relax restriction of the working frequency about thickness of a printed circuit board by providing a capacitive stub of a suitable dimension on a gate line of an FET element, and cancelling an inductance component contained in series in a terminal resistance between the gate line and an earth surface. CONSTITUTION:From a gate terminal G, a drain terminal D and a source terminal S of an FET element 10 for constituting an amplifying part, a conductor pattern extends, respectively, and disk-like dielectric resonator 16 is provided so as to be inserted and held by a drain line 12 and a gate line 14, and constitutes a feedback part. On the end of the gate line 14, a capacitive stub 30 is provided, and this capacitive stub 30 cancels an inductance component L contained in series in a terminal resistance 18 between the gate line 14 and an earth. In such a way, even if a printed board which is comparative thick and can be handled easily is used, a microwave oscillator of a high frequency of >=10 or more GHz can be prepared.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a dielectric resonator in the feedback section and an FE in the amplification section.
Regarding the microwave oscillator using a T element, in more detail, a capacitive stub is provided on the gate line of the FET element,
The present invention relates to a microwave oscillator that allows use of frequency limitations due to substrate thickness to be relaxed.

INDUSTRIAL APPLICATION This invention is a device suitable for the local oscillator used for a transmitter, a receiver, a repeater, etc. in the communication of a microwave band, for example.

[Prior Art] A microwave oscillator that combines a feedback section using a dielectric resonator and an amplification section using an FET element is conventionally known. An example of this is shown in FIG.

Conductor patterns extend from the gate terminal G, drain terminal D1, and source terminal S of the FET element lO constituting the amplifying section, and a drain line 1 extends approximately at right angles.
A disk-shaped dielectric resonator 16 is provided so as to be sandwiched between the gate line 2 and the gate line 14, and constitutes a feedback section. The tip of the gate line 14 is terminated by a terminating resistor 18 of 50Ω. Actually, the terminating resistor 18 is connected between the gate line 14 and the ground pattern 20, and the conductor pattern 2
0 is configured to be electrically connected to the ground plane on the back side through a through hole 22 indicated by two circles.

The output is taken out via a capacitor 26 attached to the tip of the source line 24 that blocks direct current components. Further, reference numeral 28 indicates a bias resistor.

In this manner, the microwave oscillator is assembled by forming a predetermined conductor pattern on a printed circuit board and mounting the FET element 1o, dielectric resonator 16, resistor 18.degree. 28, capacitor 26, etc. thereon.

[Problems to be solved by the invention] However, in conventional microwave oscillators with this type of configuration, the usable frequency is limited by the thickness of the printed circuit board, and as the frequency band increases, the printed circuit board must be made thinner. There is a problem that must be solved.

The thickness of a printed circuit board in a low frequency band (up to about IGHz) is about 1.6+ms, but if the operating frequency reaches +II [GHz], the operation may become unstable or abnormal oscillation may occur. In the conventional configuration, this is the fourth
This is because, as shown in the figure, an inductance component is equivalently included in series with the terminating resistor 18 between the gate line 14 and the ground plane. In order to minimize this inductance component, measures such as providing a large number of through holes 22 or providing the through hole 22 near the terminating resistor 18 are taken, but the influence of the inductance component still remains, and conventional technology There was a drawback that the limit of the usable frequency was determined by the thickness of the substrate.

Further, making the printed circuit board thinner has many problems in terms of processability, making it difficult to handle and causing the board to become undulating.

SUMMARY OF THE INVENTION An object of the present invention is to provide a microwave oscillator that overcomes the above-mentioned drawbacks of the prior art, can ease the frequency limitations imposed by the thickness of a printed circuit board, is easy to manufacture, and operates stably.

[Means for Solving the Problems] The present invention, which can achieve the above objects, has an amplification system that combines a feedback section using a dielectric resonator and an amplification section using an FET element. FEs that make up the department
This is a microwave oscillator in which a capacitive stub is provided on the gate line of the T element to cancel an inductance component included in series with a terminal resistor between the gate line and the ground plane.

There is no particular restriction on the formation position of the capacitive stub, and it can be changed as appropriate along the gate line.

[Function] When a capacitive stub is provided on the gate line of the FET element,
Equivalently, a capacitance is connected in parallel to a series circuit of an inductance component formed by a terminating resistor and a through hole in the ground pattern portion. Therefore, by selecting the capacitance so that the imaginary part of the combined impedance becomes zero, the influence of inductance can be substantially canceled and it can be regarded as a pure resistance. Therefore, even if the printed circuit board is thick for the operating frequency, by providing a capacitive stub with an appropriate shape, the adverse effects of the inductance component can be eliminated and stable oscillator operation can be achieved.

[Embodiment] FIG. 1 is an explanatory diagram showing an embodiment of a microwave oscillator according to the present invention, and FIG. 2 is an equivalent circuit diagram of the main part thereof.

Since the basic configuration may be the same as that of the prior art shown in FIG. 3, corresponding parts are given the same reference numerals to simplify the explanation.

Conductive patterns extend from the gate terminal G, drain terminal D, and source terminal S of the FET element 1o that constitutes the amplifying section, and a drain line 1 extends at a nearly right angle.
A disk-shaped dielectric resonator 16 is provided so as to be sandwiched between the gate line 2 and the gate line 14, and constitutes a feedback section. The tip of the gate line 14 is terminated by a terminating resistor 18 of 50Ω. Actually, the terminating resistor is connected between the gate line 14 and a long ground pattern 20 formed along the gate line 14. The ground pattern 20 is configured to be electrically connected to the ground plane on the back side through through holes 22 indicated by three circles.

The output is taken out via a capacitor 26 attached to the tip of the source line 24 that blocks direct current components. Further, reference numeral 28 indicates a bias resistor.

Now, the present invention is significantly different from the prior art in the configuration near the gate line 14. A capacitive stub 30 is provided at the end of the gate line 14 . This capacitive stub 3
0 is the terminating resistor 18 between the gate line 14 and the ground plane.
The dimensions are designed to cancel the inductance component included in series with the inductance component.

When the capacitive stub 30 is provided in this way, in terms of an equivalent circuit, as shown in FIG. are inserted in series, and a capacitance C by the capacitive stub 30 is provided in parallel therewith.

The composite impedance Z of such a circuit is as follows.

Z R+jωL 1/jωC(1-ωz
CL) * +ω''R When Z-A+jB is set, C is selected so that the imaginary part B is O.

(l-ω"CL)"+ω"R, the impedance Z of this composite circuit becomes only the real part A, which equivalently corresponds to only pure resistors being arranged. Also, this impedance Z Matching can be achieved by matching the characteristic impedance of the line.

Note that although the capacitive stub is formed at the end of the gate line in the above embodiment, it may be formed between the terminating resistor and the gate terminal depending on the case, and the position can be changed as appropriate.

[Effects of the Invention] As described above, the present invention provides a capacitive stub of appropriate dimensions on the gate line of the FET element constituting the amplification section, and reduces the inductance included in series with the terminating resistor between the gate line and the ground plane. Since the structure is configured to cancel the components, it is possible to relax the restrictions on the frequency of use depending on the thickness of the printed circuit board, and it is possible to use a relatively thick and easy-to-handle printed circuit board, such as those used for conventional boat fishing, without sufficient power. Number GH
This has the effect of making it possible to manufacture a microwave oscillator with a high frequency of z or higher.

Further, in the present invention, since the inductance component due to the through hole can be corrected as described above, it is possible to prevent abnormal oscillation from occurring, and there is an effect that stable operation can be performed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the microwave oscillator according to the present invention, FIG. 2 is an equivalent circuit diagram of the main part thereof, FIG. 3 is an explanatory diagram showing an example of the conventional technology, and FIG. FIG. 3 is an equivalent circuit diagram near a terminating resistor. 10... pET element, 12-... drain line, 1
4... Gate line, 16... Dielectric resonator, 18
...Terminal resistor, 20...Earth pattern, 22...
・Through hole, 24... Source line, 30...
Capacitive stub. Patent applicant: Fuji Electrochemical Co., Ltd. Representative: Minoru Shigeru Figure 1 + 6 112 Figure 3 Figure 4

Claims (1)

[Claims] 1. In a combination of a feedback section using a dielectric resonator and an amplification section using an FET element, the gate line of the FET element constituting the amplification section is connected in series to the terminating resistor between it and the ground plane. A microwave oscillator characterized by being provided with a capacitive stub that cancels the included inductance component.