JP2008177981A - Oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: There is a problem that a conventional thermostatic chamber type crystal oscillator is difficult to finely adjust an oscillation frequency, and cost is increased due to replacement of parts, and adjustment work becomes complicated. An oscillator capable of performing fine adjustment of an oscillation frequency and a frequency variable amount accurately and easily with a simple configuration.
In an oscillation circuit of a thermostat crystal oscillator, a coarse adjustment coil A composed of a chip inductor and a fine adjustment coil B composed of a trimming coil are connected in series to a crystal resonator. The coil A is loaded so as to match the desired oscillation frequency and the frequency variable amount, and the coil B is trimmed and the inductance value is finely adjusted to obtain the desired oscillation frequency and frequency variable amount. It is an oscillator that can be adjusted.
[Selection] Figure 1

Description

  The present invention relates to an oscillator including a thermostatic chamber that keeps a constant temperature, and more particularly to an oscillator that can finely adjust an oscillation frequency and a frequency variable amount with high accuracy.

[Description of Prior Art]
The Oven Controlled Crystal Oscillator (OCXO) is a crystal unit mounted in a case where the temperature is kept constant, and is not affected by the environmental temperature and has stable frequency characteristics. Crystal oscillator.

  Conventionally, when adjusting the output frequency in a thermostat crystal oscillator, the adjustment has been performed by changing the crystal resonator and the elements in the circuit. Examples of elements in the circuit used for frequency adjustment include a chip inductor.

  Further, when the oscillation frequency is high, the influence of the inductance value of the circuit on the oscillation frequency is large, and the oscillation frequency is greatly changed by a minute change of the inductance value, so that adjustment is difficult.

[Prior art documents]
Incidentally, as prior art relating to a technique for adjusting the output frequency in a crystal oscillator, Japanese Patent Application Laid-Open No. 09-107239 (Patent Document 1), Japanese Patent Application Laid-Open No. 10-261631 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2003-046336. (Patent Document 3).

  Japanese Patent Application Laid-Open No. 2004-228688 includes a trimming resistor and coil parallel circuit connected in series to a crystal resonator and a trimming resistor and capacitor parallel circuit in a crystal oscillator oscillation circuit, and trimming the resistor. Describes a structure for adjusting reactance and adjusting frequency.

Patent Document 2 describes a structure in which an inductance is adjusted by trimming a coil pattern connected to another electric functional element in a circuit including a coil.
Further, Patent Document 3 describes a structure in which the frequency is adjusted by trimming the reactance pattern of the piezoelectric oscillation circuit in the oscillation circuit of the piezoelectric oscillator.

JP 09-107239 A Japanese Patent Laid-Open No. 10-261631 JP 2003-046336 A

  However, in a conventional thermostatic chamber crystal oscillator, when the oscillation frequency is adjusted by exchanging the crystal resonator or the chip inductor, the inductance of the element is a fixed constant, so that only a discrete inductance value can be obtained. Adjustments are difficult, and there is a problem in that the cost increases due to the replacement of parts and the adjustment work becomes complicated.

  In addition, since Patent Document 1 has two parallel circuits each having a resistor capable of laser trimming, the circuit scale is increased, and Patent Document 2 discloses that a part of a coil is melted / aggregated by heat so that the coil Rather than adjusting the inductance by trimming and removing a part of the coil, Patent Document 3 provides a reactive pattern that can be trimmed on the back surface of the substrate, making the configuration complicated and the manufacturing process complicated. There is a problem of becoming.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an oscillator capable of performing fine adjustment of an oscillation frequency and a variable amount of frequency accurately and easily with a simple configuration.

  The present invention for solving the problems of the above-described conventional example, in an oscillator including a thermostatic chamber for keeping the temperature of the crystal resonator constant, in the crystal resonator, a coarse adjustment coil for coarsely adjusting the oscillation frequency, A fine adjustment coil for finely adjusting the oscillation frequency is connected in series.

  In the oscillator according to the present invention, a coarse adjustment coil having a large inductance value is used, and a fine adjustment coil having a smaller inductance value than that of the coarse adjustment coil is used for fine adjustment. The coil is characterized in that the inductance value can be changed.

  In the oscillator according to the present invention, the fine adjustment coil is a trimming coil whose inductance value can be changed by trimming.

  In the oscillator according to the present invention, the trimming coil is formed by a circuit pattern formed on a substrate.

  In the oscillator according to the present invention, the circuit pattern is provided with a trimming pattern portion in advance.

  According to the present invention, in an oscillator including a thermostatic chamber that maintains a constant temperature of the crystal unit, the crystal unit includes a coarse adjustment coil that coarsely adjusts the oscillation frequency and a fine adjustment unit that finely adjusts the oscillation frequency. Since the oscillator is connected to the coil in series, there is an effect that the oscillation frequency and the frequency variable amount can be finely adjusted accurately and easily with a simple configuration without increasing the circuit scale.

  Further, according to the present invention, since the fine adjustment coil is a trimming coil whose inductance value can be changed by trimming, the inductance value can be adjusted with high accuracy by laser trimming.

  In addition, according to the present invention, since the trimming coil is an oscillator formed by a circuit pattern formed on a substrate, manufacturing is easy and there is an effect that a simple configuration can be obtained.

  Further, according to the present invention, since the circuit pattern is provided with the trimming pattern portion in advance, the trimming operation can be easily performed and the working efficiency can be improved.

[Summary of Invention]
Embodiments of the present invention will be described with reference to the drawings.
An oscillator according to an embodiment of the present invention includes a coarse adjustment coil and a fine adjustment coil for performing rough adjustment in series with a crystal resonator in an oscillation circuit section of a crystal oscillator using a thermostatic chamber. This is an oscillator in which various types of coils are connected, the coarse adjustment coil is composed of a chip inductor, and the fine adjustment coil is composed of a trimming coil, and is suitable for a desired oscillation frequency and variable frequency as a coarse adjustment coil. A chip inductor can be selected and loaded, and the fine adjustment coil can be trimmed and adjusted to an optimum inductance value, so that the oscillation frequency and variable frequency can be adjusted accurately and easily with a simple configuration. It is.

[Configuration of Embodiment: FIG. 1]
The configuration of the oscillator according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a circuit diagram showing a configuration of a circuit portion relating to oscillation frequency adjustment in an oscillation circuit section of an oscillator according to an embodiment of the present invention.
As shown in FIG. 1, the frequency adjustment circuit portion of the oscillation circuit of the present oscillator is obtained by connecting two coils in series with a crystal resonator X.

  The coil A is a coarse adjustment coil for roughly adjusting the oscillation frequency and the frequency variable amount, and the coil B is a fine adjustment coil for fine adjustment. The inductance value of the coil A is larger than the inductance value of the coil B. The oscillation frequency and frequency variable amount of the crystal oscillator X are adjusted by changing the inductance values of the coil A and the coil B.

[Coil A]
The coil A is a coarse adjustment coil and is constituted by a chip inductor.
That is, in the coil A, a chip inductor having an optimum inductance value is selected and loaded so as to obtain a desired frequency characteristic as much as possible according to a desired oscillation frequency and frequency variable amount. The inductance value of coil A cannot be adjusted after loading.

[Configuration of coil B: FIG. 2]
Further, the coil B is a fine adjustment coil, and is constituted by a trimming coil.
Here, the configuration of the coil B will be described with reference to FIG. 2A is a schematic explanatory diagram illustrating an example of a circuit pattern of the coil B, and FIG. 2B is a schematic explanatory diagram illustrating a trimming example of the coil B.
As shown in FIG. 2A, the coil B is a circuit pattern formed in the same process as the wiring portion, and has a shape that can be easily trimmed by a laser. Here, a plurality of narrow grooves 11, 11 are formed in a rectangular metal pattern. ′ Is provided.

In particular, the groove 11 'is formed slightly shorter as a trimming pattern, and is formed so as to be capable of laser trimming so as to extend the length of the groove 11'. This facilitates trimming.
In the example of FIG. 2, the trimming groove 11 'is provided at the left end of the coil B. However, the present invention is not limited to this, and another groove 11 may be formed as the trimming groove 11'.

  Then, as shown in FIG. 2B, when the oscillation frequency is adjusted, the portion following the trimming groove 11 'of the circuit pattern of the coil B is burned and removed (trimmed) by the laser beam. Change the inductance value. Laser trimming is highly accurate and can be trimmed so as to obtain an inductance value that provides a desired frequency characteristic. In the example of FIG. 2 (b), the trimming portion 12 is formed by trimming the groove portion 11 'of the metal pattern provided in advance so as to be longer.

  A high-frequency oscillator is easily affected by inductance, and it is difficult to obtain a desired oscillation frequency and variable frequency with a chip inductor alone. However, in this oscillator, a coarse adjustment coil A made of a chip inductor is appropriately selected and loaded. Then, after making the frequency characteristics of the oscillation circuit be close to the desired oscillation frequency and frequency variable amount, the circuit pattern of the fine adjustment coil B is laser-trimmed, thereby making the desired oscillation frequency and frequency variable. It can be accurately adjusted to the amount.

  Furthermore, if it is attempted to adjust a relatively wide range of frequencies using only the coil B, it takes time for the trimming operation, or the circuit pattern becomes large and the chip area increases, which hinders the miniaturization of the entire oscillator. By using the coil A for coarse adjustment and the coil B for fine adjustment in combination, the coil B can be trimmed only by fine adjustment, the frequency adjustment work time can be shortened, and the frequency adjustment can be performed accurately with a simple configuration. Is something that can be done.

[Relationship between inductance and oscillation frequency: Fig. 3]
Next, frequency adjustment in the high-frequency oscillator will be described with reference to FIG. FIG. 3 is a graph showing changes in oscillation frequency accompanying changes in inductance.
In FIG. 3, in the configuration shown in (a), that is, in the configuration in which the coil L2 is connected in series with the crystal unit X, the change in the oscillation frequency of the high-frequency oscillator when the inductance value of L2 is changed is shown in (b). ).
As shown in FIG. 3B, with L2 = 120 nH as a reference, it can be seen that when L2 is decreased, the oscillation frequency increases, and when it is increased, the oscillation frequency decreases.

[Effect of the embodiment]
According to the oscillator according to the embodiment of the present invention, in the oscillation circuit of the thermostat crystal oscillator, the coarse adjustment coil A composed of a chip inductor and the fine adjustment coil B composed of a trimming coil are provided. Since the oscillator is connected in series with the crystal resonator, the coil A is loaded so as to match the vicinity of the desired oscillation frequency and frequency variable amount, and further, the coil B is trimmed to finely adjust the inductance. The oscillation frequency and frequency variable amount can be adjusted to the desired oscillation frequency, and the oscillation frequency and frequency variable amount can be adjusted easily and accurately with a simple configuration.

  Also, by using the coil A for coarse adjustment and the coil B for fine adjustment in combination, the adjustment time of the frequency and the frequency variable amount can be greatly increased as compared with the case where the element is exchanged or adjustment is performed only by trimming. This can be shortened, and there is an effect that does not increase the circuit scale and does not hinder downsizing of the oscillator.

  The present invention relates to an oscillator that can adjust a frequency and a frequency variable amount with high accuracy, particularly in a thermostatic oven type oscillator.

It is a circuit diagram which shows the structure of the circuit part regarding the oscillation frequency adjustment in the oscillation circuit part of the oscillator which concerns on embodiment of this invention. FIG. 2B is a schematic explanatory diagram illustrating an example of a circuit pattern of the coil B, and FIG. It is a graph which shows the change of the oscillation frequency accompanying the change of an inductance.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Groove part, 11 '... Trimming groove part, L ... Coil, X ... Quartz crystal unit

Claims (5)

  In an oscillator having a thermostatic chamber for maintaining a constant temperature of the crystal unit, a coarse adjustment coil for coarse adjustment of the oscillation frequency and a fine adjustment coil for fine adjustment of the oscillation frequency are connected in series to the crystal unit. An oscillator characterized by being connected.   The coarse adjustment coil uses a coil having a large inductance value, the fine adjustment coil uses a coil having a smaller inductance value than the coarse adjustment coil, and the fine adjustment coil can change the inductance value. The oscillator according to claim 1, wherein:   3. The oscillator according to claim 2, wherein the fine adjustment coil is a trimming coil whose inductance value can be changed by trimming.   4. The oscillator according to claim 3, wherein the trimming coil is formed by a circuit pattern formed on the substrate.   5. The oscillator according to claim 4, wherein a trimming pattern portion is provided in advance in the circuit pattern.

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