JPH05335834A - Oscillator circuit - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To enable wide and accurate adjustment of the oscillation frequency adjustment range in an oscillation circuit having a microstrip line in the resonance section. [Structure] This oscillator circuit includes a substrate 10a and a substrate 10a.
It includes a microstrip line 10 having a strip conductor 10b and an earth pattern which are opposed to each other with the strip conductor 10b interposed therebetween. Then, the connection pattern 11 formed at one end of the strip conductor 10b and connected to the ground pattern through the first through hole 18, and the fine adjustment stubs 13a to 13a.
13e and a coarse adjustment stub 14 are provided. One end of the fine adjustment stubs 13a to 13e is the strip conductor 10
The other end of b is connected to the connection pattern 11 for finely adjusting the oscillation frequency. The coarse adjustment stub has one end connected to the connection pattern 11 and the other end connected to the ground pattern via the second through hole 15, and is for roughly adjusting the oscillation frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillator circuit, and more particularly to an oscillator circuit having a microstrip line in a resonance section.

[0002]

2. Description of the Related Art Conventionally, a frequency variable oscillator for mobile communication represented by a car telephone employs a microstrip line as a resonator of a resonance circuit section.
The resonance circuit section includes a microstrip line including a substrate made of a dielectric material, a strip conductor formed on the front surface of the substrate, and a ground pattern formed on the back surface of the substrate. A connection pattern (ground land) is formed at one end of the strip conductor, and this ground land is connected to the ground pattern on the back surface of the substrate through a through hole.

[0003]

In the oscillation circuit including the conventional microstrip line, a plurality of frequency adjusting stubs are arranged in parallel between the strip conductor and the ground land, and trimming of these is desirable. The oscillation frequency of is obtained. However, due to variations in the circuit constants of the resonant circuit section, variations in the dielectric constant of the substrate, and variations in the manufacturing conditions for the microstrip line, the desired oscillation frequency can be obtained simply by trimming the conventional frequency adjustment stub. You may not be able to. Therefore, as is clear from the graph shown in FIG.
There is a problem that the yield of products becomes poor because adjustment is not possible for those that vary in the high frequency region (hatched region). In FIG. 7, the vertical axis represents the oscillation frequency and the horizontal axis represents the lot number N.

An object of the present invention is to make it possible to widen the adjustment range of the oscillation frequency and to accurately adjust the frequency.

[0005]

An oscillator circuit according to the present invention includes a microstrip line having a dielectric substrate and a strip conductor and a ground pattern which are opposed to each other with the dielectric substrate interposed therebetween. The connection pattern, a plurality of fine adjustment stubs, and a coarse adjustment stub are provided. The connection pattern is formed at one end of the strip conductor and is connected to the ground pattern via the first conductive portion. The plurality of fine adjustment stubs, one end is connected to the strip conductor and the other end is connected to the connection pattern,
It is a stub for finely adjusting the oscillation frequency. The coarse adjustment stub has one end connected to the connection pattern and the other end connected to the ground pattern via the second conductive portion, and is a stub for roughly adjusting the oscillation frequency.

[0006]

In the oscillation circuit according to the present invention, when the oscillation frequency is far away from the target frequency, the coarse adjustment stub is cut, for example, or the length is changed to mainly change the inductance of the microstrip line. Change the component to bring it closer to the target frequency. When the frequency is close to the target frequency, the fine adjustment stub is trimmed, for example, to finely adjust the oscillation frequency.

As described above, the coarse adjustment stub enables frequency adjustment in a wide range, and the fine adjustment stub enables accurate frequency adjustment.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a basic pattern of a resonance circuit portion used in an oscillator circuit of the present invention, and FIG. 2 shows an equivalent circuit thereof. The microstrip line 1 includes a dielectric substrate 1a
And the strip conductor 1 formed on the surface of the substrate 1a
b and a ground pattern on the back surface of the substrate 1a (not shown). A ground land 2 as a connection pattern is formed at one end (the left end in FIG. 1) of the microstrip line 1. The ground land 2 is formed along the strip conductor 1b at a predetermined distance from the tip of the main ground land 2a and the main ground land 2a formed to extend to the side of the strip conductor 1b. It is composed of an auxiliary ground land 2b. A first through hole 3 is formed in the main ground land 2a, and is electrically connected to the ground pattern formed on the back surface of the substrate through the first through hole 3.

A plurality of fine adjustment stubs 41, 42, 43, 4 are provided between the strip conductor 1b and the sub-ground land 2b.
4, 45 are provided in parallel. One end of each of the fine adjustment stubs 41 to 45 is connected to the microstrip line 1, and the other end is connected to the sub ground land 2b. Further, a coarse adjustment stub 5 is formed so as to extend continuously from the sub-ground land 2b and in parallel with the strip conductor 1b. One end of the coarse adjustment stub 5 is connected to the sub-ground land 2b, and the other end is electrically connected to the ground pattern on the back surface of the substrate through the second through hole 6.

FIGS. 3 and 4 show the basic pattern of the microstrip line with a stub for frequency adjustment shown in FIG.
It is a plan view when applied to an actual resonance circuit. 4 is a cross section taken along the line IV-IV of FIG. As shown in these figures, the microstrip line 10 includes a dielectric substrate 1
0a, the J-shaped strip conductor 10b formed on the surface of the substrate 10a, and the strip conductor 10 on the back surface of the substrate 10a.
and a ground pattern 10c formed so as to face b. A ground land 11 including a main ground land 11a and a sub ground land 11b is formed at one end of the strip conductor 10b. The other end of the strip conductor 10 is connected to the main ground land 1 via the additional capacitance 12.
It is connected to 1a. Further, a plurality of fine adjustment stubs 13a to 13e for fine adjustment of the oscillation frequency are arranged in parallel between the sub ground land 11b and the strip conductor 10b. Further, a coarse adjustment stub 14 continuously extending along the strip conductor 10b is formed from the sub-ground land 11b. Coarse adjustment stub 14
Is a stub for roughly adjusting the oscillation frequency, and its tip is electrically connected through a through hole 15 to a ground pattern 10c formed on the back surface of the substrate 10a. In addition, the main ground land 11a has a through hole 18
Is electrically connected to the ground pattern 10c via.

Here, an example of dimensions of the circuit pattern of FIG. 3 is shown. When the target oscillation frequency is set to about 800 MHz, for example, the strip conductor 10b and the coarse adjustment stub 1 are used.
4, the distance a between the center of the fine adjustment stub 13a and the through hole 15 and the width c of the coarse adjustment stub are as follows. a = 0.7 mm b = 1.5 mm c = 0.3 mm The line length of the microstrip line 10 is 10 m.
m, width (strip conductor) is 0.8 mm.

In the case of adjusting the oscillation frequency in the circuit as in the above example, 1 is set for the target frequency of 800 MHz.
When the distance is 5 MHz or more, the coarse adjustment stub 14 is first cut to perform the coarse adjustment. Next, fine adjustment stub 13a
.About.13e are sequentially cut as needed to obtain a target frequency. On the other hand, when the difference between the target frequency and the oscillation frequency is smaller than 15 MHz, only the fine adjustment stubs 13a to 13e are sequentially cut as needed to obtain the target frequency. In the above example, 14 MHz by cutting the coarse adjustment stub 14,
Further, by cutting the fine adjustment stubs 13a to 13e, the frequency can be lowered by about 3 MHz per one, and the frequency can be adjusted in a range about twice as large as that of the conventional one having only the fine adjustment stub. ..

FIG. 5 shows changes in the oscillation frequency when the coarse adjustment stub 14 and the fine adjustment stubs 13a to 13e are cut. In FIG. 5, when the coarse adjustment stub 14 is cut at point P1, the fine adjustment stubs 13a to 13e are sequentially cut at points P2 to P6 from the second through hole 15 side toward the first through hole 18 side. The change in frequency is shown in FIG. The characteristic indicated by the broken line in FIG. 5 shows the characteristic when the frequency is adjusted only by the conventional fine adjustment stub.

FIG. 6 is a circuit diagram of a voltage controlled oscillator circuit having a resonance circuit using a microstrip line according to an embodiment of the present invention. This oscillator circuit includes a resonance circuit unit 20.
And a negative resistance circuit section 21 and an amplification circuit section 22. The resonance circuit section 20 includes a microstrip line SL1 with a frequency adjusting stub shown in FIG. 3, a varicap Cv whose capacitance changes according to a control voltage, bypass capacitors C1 and C2, and a variable range of the voltage controlled oscillation frequency. Capacitor C3 for determining and capacitor C
4, C5, resistors R1 and R2, and another microstrip line SL2. Further, the negative resistance circuit unit 21 includes a transistor Q1 and capacitors C6 and C.
7 and C9, and a resistor R6. Further, the amplifier circuit section 22 includes a transistor Q2, a microstrip line SL3, capacitors C8, C10, C11,
It is composed of C12 and resistors R3 and R4.

The capacitor C4 in the resonance circuit section 20 corresponds to the additional capacitance 12 in FIG. [Other Embodiments] (a) In the above embodiments, the coarse adjustment stub 14 is cut to perform the coarse adjustment of the oscillation frequency.
The frequency may be adjusted by changing the length of the coarse adjustment stub. At this time, the oscillation frequency rises by shortening the coarse adjustment stub. (B) In the above embodiment, the microstrip line is shown in FIG.
However, the present invention can be similarly applied to a straight microstrip line.

[0016]

As described above, in the present invention, the coarse adjustment stub and the fine adjustment stub are connected in parallel to the microstrip line, and the frequency is adjusted by the both stubs according to the difference between the oscillation frequency and the target frequency. Since I tried to change
The oscillation frequency can be adjusted in a wide range and accurately.

[Brief description of drawings]

FIG. 1 is a view showing a basic pattern of a microstrip line with a frequency adjusting stub according to the present invention.

FIG. 2 is an equivalent circuit diagram of FIG.

FIG. 3 is a plan view of a microstrip line with a frequency adjusting stub according to an embodiment of the present invention.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a diagram showing a relationship between a stub to be cut and a change in oscillation frequency.

FIG. 6 is a circuit diagram of an oscillator circuit in which an embodiment of the present invention is adopted.

FIG. 7 is a diagram for explaining the function and effect of the present invention.

[Explanation of symbols]

 1,10 Microstrip line 2,11 Ground land (connection pattern) 13a to 13e, 41,45 Fine adjustment stub 5,14 Coarse adjustment stub 3,6,15,18 Through hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyuki Tanaka 1-1 Yamashita-cho, Kokubun-shi, Kagoshima Prefecture Kyocera Stock Company (72) Inventor Yasuto Fujii 1-1 Yamashita-cho, Kokubun-shi, Kagoshima Kyocera Stock Company In Kagoshima Kokubun Plant (72) Inventor Satoru Tanaka 1-1 Yamashita-cho, Kokubun-shi, Kagoshima Prefecture Kyocera Stock Company Kagoshima Kokubun Plant (72) Inventor Shigeo Nakamura 1-1 Yamashita-cho, Kokubun City, Kagoshima Prefecture Kagoshima Kokubu Plant Within

Claims (1)

[Claims] 1. An oscillation circuit including a dielectric substrate and a microstrip line having a strip conductor and an earth pattern, which are opposed to each other with the dielectric substrate interposed therebetween, and a first conducting portion formed at one end of the strip conductor. A plurality of fine adjustment stubs for finely adjusting the oscillation frequency, one end of which is connected to the strip conductor and the other end of which is connected to the connection pattern, and one end of which is the connection pattern An oscillator circuit, the other end of which is provided with a coarse adjustment stub for coarsely adjusting an oscillation frequency connected to the ground pattern via a second conducting portion.