JP2001094346A - Voltage control oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the fine adjustment of an oscillation frequency at the time of oscillating a high frequency by a voltage control oscillator. SOLUTION: A first resonance circuit 4 having a first micro strip line 8 and a second resonance circuit 5 having a second micro strip line 9, which are connected in parallel, constitute a part of a tank circuit 2. A third micro strip line 10 connected to the first micros strip line 8 and the second micro strip line 9 is connected to a ground conductor 12 through plural through holes 13a to 13f.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstrip line (hereinafter referred to as MS) suitable for adjusting an oscillation frequency.
L).

[0002]

2. Description of the Related Art A conventional voltage controlled oscillator has one MSL.
To adjust the oscillation frequency to a predetermined frequency.

FIG. 4 is a circuit diagram of a conventional voltage controlled oscillator, and FIG. 5 is an explanatory diagram showing trimming of MSL in the conventional voltage controlled oscillator.

[0004] In FIG. 4, the voltage controlled oscillator has an oscillation transistor 21 and a tank circuit 22, and the tank circuit 22 has feedback capacitors 23 a and 23 b and a resonance circuit 24. The resonance circuit 24 includes a varactor diode 25 and a microstrip line (hereinafter, referred to as MSL) 26.

[0005] The oscillation frequency of this voltage controlled oscillator depends on the characteristics of each element, but the characteristics of each element vary from product to product, so that the oscillation frequency also varies from product to product. Therefore, the MSL 26 is trimmed to a predetermined oscillation frequency while a predetermined voltage is applied to the varactor diode 25, and the MSL 26
Adjust the impedance value of.

When trimming the MSL 26, FIG.
As shown in (1), the MSL 26 is cut by a drill or the like (not shown) to provide a cut groove 27.

[0007]

However, when the oscillation frequency is high (for example, 3 GHz or more), the inductance value of the MSL 26 must be reduced.
The length of 26 is necessarily shortened. Therefore, when the MSL 26 is trimmed to adjust the oscillation frequency,
Even if L26 is slightly cut, the oscillation frequency fluctuates greatly, making it difficult to finely adjust the oscillation frequency.

It is an object of the present invention to provide a voltage controlled oscillator that can easily finely adjust the oscillation frequency even when the oscillation frequency is high.

[0009]

In order to solve the above problems, a voltage controlled oscillator according to the present invention is connected to a first microstrip line provided on an upper surface of a substrate and one end of the first microstrip line. First varactor diode, a second microstrip line provided on the upper surface of the substrate, and a second varactor diode connected to one end of the second microstrip line Having a second resonance circuit, the first resonance circuit and the second resonance circuit are connected in parallel, the oscillation frequency by the first resonance circuit and the second resonance circuit It was set.

The voltage controlled oscillator according to the present invention further comprises a third microstrip line connecting the other end of the first microstrip line and the other end of the second microstrip line, The first resonance circuit and the second resonance circuit are connected in parallel by a microstrip line, a ground conductor is provided on the lower surface of the substrate, and the third microstrip line and the ground conductor are connected by a plurality of microstrip lines. The plurality of through-holes were connected along a length direction of the third microstrip line.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A voltage controlled oscillator according to the present invention and a method for adjusting the frequency of the voltage controlled oscillator will be described with reference to FIGS. 1, 2 and 3. FIG.

As shown in FIG. 1, the voltage controlled oscillator has an oscillating transistor 1 and a tank circuit 2. The tank circuit 2 includes feedback capacitors 3a and 3b, a first resonance circuit 4 and a second resonance circuit. And the resonance circuit 5 described above.

The first resonance circuit 4 is configured by connecting one end (anode) of a first varactor diode 6 and one end of a first microstrip line 8 (hereinafter, referred to as a first MSL). The second resonance circuit 5 is configured by connecting one end (anode) of a second varactor diode 7 and one end of a second microstrip line 9 (hereinafter, referred to as a second MSL). The other end (cathode) of the first varactor diode 6 is connected to the other end (cathode) of the second varactor diode, and is connected to the base of the oscillating transistor 1 at high frequency.

The other end of the first MSL 8 is connected to one end of a third microstrip line (hereinafter referred to as a third MSL) 10, and the other end of the second MSL 9 is connected to the third MSL 1
0 is connected to the other end. Then, the third MSL 10 is grounded, and the first resonance circuit 4 and the second resonance circuit 5 are connected in parallel by the third MSL 10.

When adjusting the oscillation frequency of the voltage-controlled oscillator, the first varactor diode 6 and the second varactor diode 7 are applied with a predetermined voltage so that the first varactor diode 6 and the second varactor diode 7 have a predetermined oscillation frequency. The resonance frequency of the tank circuit 2 is adjusted by changing the inductance value of only the MSL8 (or the second MSL8). Since the first resonance circuit 4 and the second resonance circuit 5 are connected in parallel,
When only the first MSL 8 (or the second MSL 9) is trimmed, the amount of change in the combined impedance of the first resonance circuit 4 and the second resonance circuit 5 is small, so that the change in the resonance frequency of the tank circuit 2 The amount also becomes small, and fine adjustment of the oscillation frequency becomes possible.

The specific shapes of the first resonance circuit 4 and the second resonance circuit 54 used in such a voltage controlled oscillator will be described with reference to FIG.

As shown in FIG. 2, the first MSL 8, the second MSL 9 and the third MSL 10 are formed as a copper foil pattern on the upper surface of the substrate 11 (see FIG. 3). The first MSL 8 and the second MSL 9 are disposed substantially in parallel, and the other end of the first MSL 8 and the other end of the second MSL 9 are connected by a third MSL 10. M
SL9 and third MSL10 are integrally formed.

The third MSL 10 is provided with a plurality of through holes 13a to 13f.

As shown in the cross-sectional view of FIG. 3, a ground conductor 12 is provided on the lower surface of the substrate 11 by a copper foil pattern, and the third conductor is provided through through holes 13a to 13f.
SL10 and ground conductor 12 are connected.

When adjusting the oscillation frequency, the first MSL 8 in the through holes 13a to 13f is adjusted.
Holes 14 are drilled in order from the through hole 13f closest to the first MSL 8 and a part of the third MSL 10 is added to the first MSL 8 to connect from the connection position with the first varactor diode 6. Adjust the inductance value by changing the length to the point. In this case, since the change in the inductance value is relatively large, coarse adjustment can be performed. Further, since the positions of the through holes 13a to 13f are predetermined positions, it is possible to know in advance how much the inductance value changes when cutting to which through holes in order, so that the coarse adjustment can be performed quickly and accurately. When performing fine adjustment that cannot be adjusted by coarse adjustment, the first MSL
8 is cut to provide a cutting groove 15. In this case, since the length from the first varactor diode 6 to the ground point does not change, fine adjustment is possible.

[0021]

As described above, in the voltage controlled oscillator of the present invention, the first resonance circuit having the first microstrip line and the second resonance circuit having the second microstrip line are connected in parallel. Therefore, the oscillation frequency can be finely adjusted by trimming the first microstrip line or the second microstrip line.

Further, in the voltage controlled oscillator of the present invention, since the third microstrip line is connected to the ground conductor through a plurality of through holes, the oscillation frequency can be adjusted by cutting the through holes. The length from the connection position between the first microstrip line and the first varactor diode to the ground point of the third microstrip line can be changed. Therefore, the coarse adjustment can be performed quickly and accurately.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a voltage controlled oscillator according to the present invention.

FIG. 2 is a diagram illustrating a shape of a microstrip line used in the voltage controlled oscillator of the present invention.

FIG. 3 shows a sectional view of the voltage controlled oscillator of the present invention.

FIG. 4 is a circuit diagram of a conventional voltage controlled oscillator.

FIG. 5 is a diagram illustrating a shape of a microstrip line used in a conventional voltage controlled oscillator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 oscillation transistor 2 tank circuit 3 a, 3 b feedback capacitor 4 first resonance circuit 5 second resonance circuit 6 first varactor diode 7 second varactor diode 8 first microstrip line 9 second microstrip line 10 Third microstrip line 11 Substrate 12 Ground conductor 13a to 13f Through hole 14 Hole 15 Cutting groove 21 Oscillation transistor 22 Tank circuit 23a, 23b Feedback capacitor 24 Resonant circuit 25 Varactor diode 26 Microstrip line 27 Cutting groove

Claims (2)

[Claims] A first resonant circuit comprising: a first microstrip line provided on an upper surface of a substrate; a first varactor diode connected to one end of the first microstrip line; A second microstrip line provided in, and a second resonance circuit consisting of a second varactor diode connected to one end of the second microstrip line, the first resonance circuit and A voltage controlled oscillator wherein the second resonance circuit is connected in parallel, and an oscillation frequency is set by the first resonance circuit and the second resonance circuit. 2. A third microstrip line for connecting the other end of the first microstrip line and the other end of the second microstrip line, wherein the third microstrip line is used for the first microstrip line. Connecting the third resonance circuit and the second resonance circuit in parallel, providing a ground conductor on the lower surface of the substrate, connecting the third microstrip line and the ground conductor with a plurality of through holes, 2. The voltage controlled oscillator according to claim 1, wherein said through hole is provided along a length direction of said third microstrip line.