JP2000244242A - Frequency adjustment method for vco - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the number of parts and also to reduce the area of a circuit for the reduction of both size and cost of a VCO by trimming a frequency adjustment inductor via a laser beam machine to oscillate the VCO frequency at a prescribed level. SOLUTION: The inductors MS1 and MS2 are formed in the copper foil circuit patterns, and the necessary inductance is given to each inductor according to the width, length and bending shape of the pattern. One of both ends of the MS2 and the anode of a diode D1 are connected to a ground plane formed on the backside via a through-hole TH, and the inductance of the MS2 is adjusted to secure the desired output frequency. The circuit component parts excluding the inductors are mounted on a printed circuit board to construct a VCO. Then the intermediate part of the MS2 is irradiated by a laser beam for trimming a groove G. Thus, the inductance of the MS2 is adjusted so that the oscillation frequency is adjusted at a desired level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VCO frequency adjusting method, and more particularly to a VCO frequency adjusting method capable of reducing the number of components.

[0002]

2. Description of the Related Art
As a method of adjusting the oscillation frequency of the VCO, there are known methods such as a method of adjusting a variable coil, a method of adjusting a plate-shaped trimmer inductor, and a method of adjusting a trimmer capacitor. Alternatively, since a trimmer capacitor or the like is required, the number of parts is large, and there is a limit to miniaturization of the substrate.

[0003] Therefore, there arises a technical problem to be solved in order to reduce the number of components and downsizing of the VCO, and an object of the present invention is to solve the above problem.

[0004]

SUMMARY OF THE INVENTION The present invention proposes to achieve the above object, and comprises forming a frequency adjusting inductor in a VCO circuit on a printed wiring board serving as a circuit board of a VCO by a circuit pattern. It is another object of the present invention to provide a VCO frequency adjusting method in which the inductor is trimmed by a laser beam machine to oscillate the VCO frequency at a specified frequency.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram of the VCO, FIG. 2 is a front view of the VCO in which the circuit of FIG. 1 is mounted on a printed wiring board PCB, and terminals # 1 are control voltage input terminals Vt, # 2, # 5.
Is a ground terminal GND, # 3 is a power supply terminal Vcc, and # 4 is an output terminal Out.

As shown in FIG. 1, four inductors MS1, MS2, MS3, and MS4 are used in a VCO circuit. FIG. 2 shows only inductors MS1 and MS2. Inductors MS1, MS2, MS
3 and MS4 are each formed by a copper foil circuit pattern of a printed wiring board, and are given the required inductance by the width and length of the pattern and the bent shape.

[0007] One end of the inductor MS2 and the diode D1
Is connected to the ground plane on the back surface through the through hole TH of the printed wiring board.
The desired output frequency is obtained by adjusting the inductance of S2.

After mounting a circuit component other than the inductor on the printed wiring board to form a VCO, the intermediate portion of the inductor MS2 is irradiated with laser light from a laser scriber to trim the groove G as shown in FIG. Inductor MS
By adjusting the inductance of 2, the oscillation frequency can be adjusted to a desired frequency.

FIG. 4 shows another embodiment of an inductor formed by a circuit pattern, in which a plurality of inductors MS are connected in parallel, and one or more inductors MS are connected as necessary like the inductor at the right end in the figure. By cutting the inductor MS by laser trimming, a desired inductance can be obtained.

The present invention is not limited to the above embodiment, and various modifications are possible within the technical scope of the present invention, and it goes without saying that the present invention extends to those modifications. is there.

[0011]

As described above, the present invention has been conventionally used because the inductor is formed by the circuit pattern of the printed wiring board and the frequency of the VCO is adjusted by laser trimming the circuit pattern of the inductor portion. Inductor components are not required, and the number of components and the circuit area are reduced, which is effective for miniaturization and cost reduction.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a VCO.

FIG. 2 is a front view of the VCO circuit board before laser trimming.

FIG. 3 is a front view of the VCO circuit board after laser trimming.

FIG. 4 is a front view of a VCO circuit board according to another embodiment.

[Explanation of symbols]

 PCB Printed wiring board MS1, MS2 Inductor G Groove (by laser processing)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuichi Awa 95-2, Iizuka-shi, Iizuka-cho, Minami-Akita-gun, Akita Prefecture F-term (reference) 4E068 AC00 DA11 4E351 BB09 BB18 FF18 GG20 5J081 AA03 AA11 CC42 DD21 EE02 EE03 EE09 EE18 GG01 JJ23 KK09 KK22 LL01 MM01 MM07

Claims (1)

[Claims] 1. A printed wiring board serving as a circuit board of a VCO,
A VCO frequency adjustment method in which a frequency adjustment inductor in a VCO circuit is formed by a circuit pattern, and the inductor is trimmed by a laser beam machine to oscillate the VCO frequency at a specified frequency.