JPH06318819A - Method for adjusting feedback quantity for high frequency generating circuit and high frequency generator - Google Patents

Abstract

PURPOSE:To provide the method for adjusting feedback quantity for a high frequency oscillating circuit in which the feedback quantity is simply adjusted and the high frequency oscillator. CONSTITUTION:An open stub 11 comprising a microstrip line is provided to a source of a FET 1 constituting the microwave oscillating circuit whose gate is connected to a dielectric resonator 4 and whose drain is connected to microstrip lines 5, 6 respectively, and the feedback quantity of the oscillating circuit is adjusted by varying the area of an open stub 11 to vary a gate-source capacitance of the FET 1. Thus, even when an oscillation output and a load fluctuation characteristic differs from desired characteristics due to the some difference from the characteristic of field effect transistors(TRs) depending on a production lot or the like, since it is not required to revise a bias circuit for the field effect TR to vary the feedback quantity different from a conventional circuit, the labor of feedback quantity adjustment is considerably reduced more than that of the conventional circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feedback amount adjusting method for a high frequency oscillator and a high frequency oscillator.

[0002]

2. Description of the Related Art In recent years, the development of satellite broadcasting or high-frequency wireless communication has been remarkable, and the demand for satellite broadcast receivers and high-frequency wireless communication equipment has been rapidly increasing. For these high-frequency devices, a small-sized high-frequency oscillation circuit capable of obtaining a stable oscillation frequency is indispensable.

A microwave band oscillator circuit as an example of such a high frequency oscillator circuit is shown in FIG. In the figure, 1 is a field effect transistor (hereinafter referred to as FET), and one end of a microstrip line 3 whose other end is terminated by a resistor 2 is connected to its gate terminal. Four
Is a dielectric resonator and is connected to the microstrip line 3 at a position at a predetermined distance L from one end of the microstrip line 3.

Further, a predetermined positive voltage Vd is applied to the drain of the field effect transistor 1 via the microstrip line 5, and a microstrip line 6 with an open end is provided on the power supply side of the microstrip line 5. It is connected. That is, the length of each of the microstrip lines 5 and 6 is set to λ / 4 (λ is an in-line wavelength of the oscillation frequency), one end of the microstrip line 5 is connected to the drain of the FET 1, and the other end is connected to the power source. It is connected to the terminal 5c. Further, one end of the microstrip line 6 is connected in the middle of a connecting line connecting the other end of the microstrip line 5 and the power supply connection terminal, and the position thereof is set at a position λ / 4 apart from the other end of the microstrip line 5. Has been done. Further, the other end of the microstrip line 6 is open.

The source of the field effect transistor 1 is grounded via a load resistor 7 and is also connected to an output terminal 10 via a capacitor 8 and an attenuator 9.

As is well known, the above-mentioned components are integrated and formed on a substrate made of ceramic or the like.

According to the microwave band oscillating circuit having the above-mentioned structure, the FET 1 oscillates at the resonance frequency of the dielectric resonator 4, the oscillation output is supplied to the load resistor 7, and only the high frequency component thereof is supplied to the capacitor 8 and The signal is output from the output terminal 10 via the attenuator 9.

[0008]

However, in the above-mentioned conventional microwave band oscillator circuit, its oscillation output and load fluctuation characteristics depend on the amount of feedback determined by the gate-source capacitance of the FET1. . Therefore, when the oscillation output and the load variation characteristics are different from the desired ones due to slight differences in the characteristics of the FET1 depending on the production lot or the like, it is necessary to change the bias circuit of the FET1 in order to change the feedback amount. The circuit design has to be redone, which is very troublesome.

In view of the above problems, an object of the present invention is to provide a high-frequency oscillator circuit feedback amount adjusting method and a high-frequency oscillator, which can easily adjust the feedback amount.

[0010]

In order to achieve the above object, the present invention provides, in claim 1, a field effect transistor having a gate connected to a dielectric resonator through a microstrip line, and the field effect transistor. A method of adjusting the amount of feedback in a high-frequency oscillation circuit, comprising: an open-ended microstrip line having a line length of ¼ wavelength connected to the drain of the field effect transistor; and a load resistor connected to the source of the field-effect transistor. A high frequency for adjusting the amount of feedback by trimming the other end of the feedback amount adjusting microstrip line, one end of which is connected to the source of the field effect transistor and the other end of which is open. We propose a method of adjusting the feedback amount of the oscillator circuit.

Further, according to a second aspect of the present invention, the field effect transistor whose gate is connected to the dielectric resonator through the microstrip line, and the end open of the line length ¼ wavelength which is connected to the drain of the field effect transistor. A high-frequency oscillator comprising a microstrip line and a load resistor connected to the source of the field-effect transistor on a substrate, wherein one end is connected to the source of the field-effect transistor on the substrate, and A high-frequency oscillator is provided in which a feedback amount adjusting microstrip line having an open end is provided and a partition wall made of an insulating material for partitioning one end side from the other end side is formed on the surface of the feedback amount adjusting microstrip line. .

[0012]

According to the method of adjusting the amount of feedback of the high-frequency oscillator circuit according to claim 1 of the present invention, the external feedback capacitance between the gate and the source of the field effect transistor is formed by the microstrip line for adjusting the amount of feedback, and the external feedback is provided. The feedback amount of the entire oscillation circuit is determined by the combined capacitance of the capacitance and the gate-source capacitance inside the field effect transistor. Also, the external feedback capacitance is changed by trimming the feedback amount adjusting microstrip line. As a result, the combined capacitance is changed and the feedback amount of the entire oscillation circuit is changed.

According to another aspect of the high-frequency oscillator, the feedback amount adjusting microstrip line forms an external feedback capacitance between the gate and the source of the field effect transistor, and the external feedback capacitance and the inside of the field effect transistor. The total amount of feedback of the oscillator circuit is determined by the combined capacitance between the gate-source capacitance of the. The external feedback capacitance is changed by trimming the feedback amount adjusting microstrip line. As a result, the combined capacitance changes, and the feedback amount of the entire oscillation circuit changes. Further, the feedback amount adjusting microstrip line and the partition wall are formed on the substrate before mounting the components such as the field effect transistor. Thereby, when the source of the field effect transistor and one end side of the feedback amount adjusting microstrip line are soldered at the time of mounting the component on the substrate, the feedback amount adjusting microstrip line is separated by the partition wall. The solder is prevented from flowing into the other end.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a microwave band oscillator circuit according to an embodiment. In the figure, the same components as those in the conventional example described above are designated by the same reference numerals, and the description thereof will be omitted. Further, a difference between the conventional example and the present example is that an open stub 11 for adjusting the feedback amount is provided, which is a microstrip line having one end connected to the source of the FET 1 and the other end opened.

The microwave band oscillator circuit of this embodiment is shown in FIG.
As shown in FIG. 3, a microwave oscillator is formed by being formed on the surface of a rectangular ceramic substrate (hereinafter referred to as a substrate) 20. On the substrate 20, the open stub 11 is
It has a predetermined width and length and is arranged at a position where trimming is possible. Note that, in FIG. 3, only a pattern of a main part according to the present invention, that is, a connecting line such as a microstrip line is shown, and the others are omitted.

Further, at the time of forming the connection line pattern on the substrate 20, between the one end side and the other end side of the surface of the open stub 11, that is, the connection portion 11a with the source of the FET1.
A partition wall 21 is formed between the adjusting portion 11b and the adjusting portion 11b by an insulating material such as glass or resist, and is placed on the substrate 20 with an F
The solder does not flow into the adjustment portion 11b when the ET1 is soldered.

According to this embodiment having the above-mentioned structure, due to the slight difference in the characteristics of the FET 1 due to the production lot or the like,
If the oscillation output and load fluctuation characteristics are different from the desired ones, the adjustment portion 11b of the open stub 11 is deleted in small amounts using a router or the like, and the gate-source capacitance of the FET1 is changed to obtain the optimum value. The amount of return can be obtained. According to the experimental results so far, the open stub 11
When the area of the open stub 11 is widened, the oscillation output decreases and the load fluctuation characteristic becomes stable.
As the area of is decreased, the oscillation output increases and the load fluctuation characteristics tend to become unstable.

Therefore, the optimum oscillation characteristic can be obtained by a very simple operation of trimming the open stub 11, and the oscillation output and the load variation characteristic can be set to the design values.

Further, since the gate-source capacitance inside the FET1 is a very small value, for example, about 0.25 pF, the gate-source outside the FET1 can be changed by a small amount. The inter-capacitance must be set to at least a value approximately equal to this, but by using the open stub 11 composed of a microstrip line, an extremely small capacitance that cannot be realized by a chip capacitor, for example, 0.05 or less. ~
A capacitance of about 0.15 pF can be obtained.

On the other hand, when the pattern is formed on the substrate 20, the connecting portion 11a of the open stub 11 and the adjusting portion 1 are formed.
Since the partition wall 21 is formed between the substrate 2 and
When the FET 1 is soldered onto the 0, the solder does not flow into the adjusting portion 11b, and the adjusting portion 1 is adjusted by the router or the like.
Fine trimming of 1b can be easily performed.

In this embodiment, only the microwave oscillator is formed on the substrate 20, but the present invention is not limited to this, and it goes without saying that it may be formed on the same substrate together with other circuits. is there.

[0022]

As described above, according to the feedback amount adjusting method for the high frequency oscillator circuit according to the first aspect of the present invention, the external feedback capacitance is changed by trimming the feedback amount adjusting microstrip line. Since the amount of feedback of the entire oscillation circuit can be easily changed, even if the oscillation output and load fluctuation characteristics differ from the desired one due to slight differences in the characteristics of the field effect transistor due to production lots, etc. Moreover, since it is not necessary to change the bias circuit of the field effect transistor in order to change the amount of feedback, the effect of adjusting the amount of feedback is greatly reduced compared to the conventional case.

Further, according to the high frequency oscillator of the second aspect, the external feedback capacitance is changed by trimming the feedback amount adjusting microstrip line, and the feedback amount of the entire oscillation circuit can be easily changed. Therefore, even if the oscillation output and load fluctuation characteristics differ from the desired one due to slight differences in the characteristics of the field effect transistor due to the production lot, etc., a bias circuit of the field effect transistor must be used to change the feedback amount as in the past. Since there is no need to change it, the labor of adjusting the feedback amount is greatly reduced compared to the conventional case. Further, when the source of the field effect transistor and one end side of the feedback amount adjusting microstrip line are soldered at the time of mounting components on a substrate, the other end side of the feedback amount adjusting microstrip line is divided by a partition wall. Since the solder is prevented from flowing in, fine trimming of the feedback amount adjusting microstrip line by a router or the like can be easily performed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional example.

FIG. 3 is a diagram showing a main part of a circuit board according to an embodiment of the present invention.

[Explanation of symbols]

1 ... FET, 2 ... Resistor, 3 ... Micro strip line, 4 ... Dielectric resonator, 5, 6 ... Micro strip line, 7 ... Load resistor, 8 ... Capacitor, 9 ... Attenuator, 10 ... Output terminal, 11 … Open stubs, 20…
Substrate, 21 ... Partition wall.

Claims (2)

[Claims] 1. A field effect transistor having a gate connected to a dielectric resonator through a microstrip line, and an open-ended microstrip line having a line length of ¼ wavelength connected to a drain of the field effect transistor. A method of adjusting a feedback amount of a high-frequency oscillation circuit, comprising: a load resistor connected to a source of the field-effect transistor; one end of which is connected to a source of the field-effect transistor;
A feedback amount adjusting microstrip line having an open other end is provided, and the feedback amount is adjusted by trimming the other end side of the feedback amount adjusting microstrip line. Adjustment method. 2. A field effect transistor having a gate connected to a dielectric resonator via a microstrip line, and an open-ended microstrip line having a line length of ¼ wavelength connected to a drain of the field effect transistor. A high frequency oscillator comprising a load resistor connected to a source of the field effect transistor on a substrate, wherein one end is connected to the source of the field effect transistor and the other end is opened on the substrate. A high frequency oscillator, characterized in that a feedback amount adjusting microstrip line is provided, and a partition wall made of an insulating material for partitioning one end side from the other end side is formed on the surface of the feedback amount adjusting microstrip line.