JP2003283247A - High-frequency oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency oscillator wherein the variation of the oscillation frequency is small even when the temperature varies. <P>SOLUTION: In this high-frequency oscillator, a dielectric resonator sealed with a sealing member having a reversible deformation characteristic is further sealed, and the internal pressure and the external pressure of the oscillator are set to a predetermined condition in accordance with the temperature characteristic of the oscillator. More specifically, when the oscillation frequency becomes higher as the temperature rises from ordinary temperature, the internal pressure is set higher than the external pressure, and when the oscillation frequency becomes lower, the internal pressure is set lower than the external pressure. In this constitution, the sealing member deforms toward the lower pressure side to change the gap between it and the dielectric resonator to relax the variation of the oscillation frequency. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency oscillator, and more particularly to a high-frequency oscillator having a small oscillation frequency fluctuation in temperature.

[0002]

2. Description of the Related Art A high-frequency oscillator using a conventional dielectric resonator has (1) a structure in which an oscillation circuit made of an MIC substrate is hermetically sealed with a housing, or (2) another MIC substrate. There is a structure in which the oscillating circuit is hermetically sealed with a metal package, which is further packaged in a housing or the like at a pressure equivalent to the pressure in the metal package. 7 and 8 are cross-sectional views of the respective high frequency oscillators. In these figures, 1 is an MIC substrate, 2 is a dielectric resonator, 3 is a package such as a housing, 4 is another MIC substrate, 5 is a metal package, and 6 is an oscillation frequency adjusting screw.

The high frequency oscillator is often combined with other circuits (mixer, amplifier, etc.) to form a module,
In the case of the high frequency oscillator shown in FIG. 7, the same M as other circuits is used.
Since the IC substrate 1 can be used, the cost can be reduced. However, if the specification of the temperature fluctuation of the oscillation frequency is strict, the yield will be poor. Therefore, as shown in FIG. 8, the oscillator hermetically sealed with a metal package is separated from other circuit boards, and these are separated. Further, the package 3 such as a housing is hermetically sealed. With such a structure, when the temperature variation of the oscillation frequency of the oscillator exceeds the standard, only the oscillator is replaced, and the decrease in yield is suppressed. However, in the conventional high frequency oscillator, even if the oscillation frequency of the dielectric resonator fluctuates when the ambient temperature fluctuates, the fluctuation cannot be corrected.

[0004]

In the high-frequency oscillator having the structure shown in FIG. 8, the yield reduction is suppressed as compared with the high-frequency oscillator having the structure shown in FIG. 7, but when the ambient temperature fluctuates, the dielectric resonator There is a problem that the oscillation frequency fluctuates, and as a result, the oscillation frequency of the high frequency oscillator fluctuates. The present invention eliminates such problems, and can suppress the decrease in yield,
It is an object of the present invention to provide a high-frequency oscillator in which the oscillation frequency fluctuates little even if the ambient temperature fluctuates.

[0005]

To achieve the above object, the invention according to claim 1 is a high-frequency oscillator in which an oscillator hermetically sealed with a member having reversible deformation characteristics is further hermetically sealed. The oscillator includes a dielectric oscillator in a resonance circuit, and when the oscillation frequency of the oscillator has a characteristic that the oscillation frequency decreases from room temperature to a rise in temperature, the dielectric resonator and the dielectric resonator In the case where the member is deformed in a concave shape so that the distance between the upper member and the member becomes narrower, and conversely has a higher oscillation frequency, the dielectric resonator and the member above the dielectric resonator The member is deformed into a convex shape so that the distance between the two becomes wider, and the fluctuation of the oscillation frequency due to the temperature fluctuation of the oscillator is alleviated.

According to a second aspect of the present invention, in the high-frequency oscillator according to the first aspect, the internal pressure and the external pressure of the oscillator are different, and the oscillation frequency of the oscillator decreases as the temperature rises from room temperature. When the internal pressure is set to be lower than the external pressure, the internal pressure is set to be higher than the external pressure when the oscillation frequency is increased. It is a thing.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a high frequency oscillator according to an embodiment of the present invention, in which 1 is an MIC substrate, 2 is a dielectric resonator,
Reference numeral 3 is a package such as a housing, 4 is another MIC substrate, 5 is a metal package, and 7 is a metal package portion made of a member having a reversible deformation characteristic above the dielectric resonator 2.

As shown in FIG. 1, the present invention is different from the conventional example in that at least the upper part of the dielectric resonator 2 is composed of a metal package portion 7 made of a member having reversible deformation characteristics. Further, at room temperature, the oscillation circuit composed of the MIC substrate 4 and the dielectric resonator 2 is sealed with a metal package 5, the oscillator is mounted on the MIC substrate 1, and the whole is sealed in a package 3 such as a casing. In this case, the internal pressure of the metal package 5 is different from the external pressure, that is, the internal pressure of the package 3 such as a housing to hermetically seal.

Assuming that the internal pressure of the metal package 5 is P1 and the external pressure, that is, the internal pressure of the package 3 such as the casing is P2, the condition for hermetically sealing is that when P1 = P2, the oscillation frequency of the oscillator is set. However, if it has a characteristic that the temperature decreases from room temperature as the temperature rises, P1 <P2 is set. On the contrary, when the oscillation frequency has a characteristic that the oscillation frequency increases as the temperature rises from room temperature, the setting is such that P1> P2.

A description will be given here using specific numerical values. First, the pressure difference is calculated from the theoretical formula as follows. PV / T = P'V '/ T' P, P ': Pressure, V, V': Volume, T, T ': Absolute temperature Note that the thermal expansion of the package etc. is not considered and the volume is treated as constant. And

FIG. 2 shows the internal pressure P1 of the metal package 5.
Is 1 atm at + 25 ° C, and the external pressure P2 is -4
The case is shown as 1 atm at 0 ° C. -40 ° C, +
When the temperature fluctuates to 60 ° C, comparing the pressure difference between the inside and outside of the metal package at -40 ° C and + 60 ° C, the pressure difference at + 60 ° C is 0.31 atm, but -40 ° C.
The pressure difference at time is 0.22 atm, and the pressure difference at + 60 ° C. is larger. That is, the pressure difference between the inside and the outside of the metal package increases as the temperature rises.

On the other hand, at a constant temperature, as an example of a high frequency oscillator, the relationship between the pressure difference between the inside and the outside of the metal package 5 in which at least the upper part of the dielectric resonator 2 is made of iron having a thickness of 0.3 mm and the oscillation frequency of the high frequency oscillator is shown. As shown in FIG.
FIG. 3 shows the oscillation frequency fluctuation amount when the internal pressure of the metal package 5 is 1 atm and the external pressure is changed to 1 to 2.6 atm. As is clear from the figure, the oscillation frequency increases by about 104 kHz every time the external pressure of the metal package 5 becomes higher than the internal pressure by 0.1 atm.
Although not shown in FIG. 3, it has been confirmed that the same relationship holds when the external pressure is lower than the internal pressure of the metal package 5. That is, each time the external pressure of the metal package 5 becomes smaller than the internal pressure by 0.1 atm, the oscillation frequency becomes lower by about 104 kHz. The fluctuation of the oscillation frequency is caused by the fluctuation of the distance between the metal package portion 7 above the dielectric resonator and the dielectric resonator 2.

FIG. 4 shows the relationship between the space between the metal package 7 and the dielectric resonator 2 above the dielectric resonator and the oscillation frequency of the high frequency oscillator at a constant temperature. It was confirmed that the oscillation frequency fluctuates by about 14 kHz when the distance between the metal resonator 7 above the dielectric resonator and the dielectric resonator changes by 1 μm.

From the above, according to the present invention, the characteristic variation of the dielectric oscillator caused by the temperature change is made to have a pressure difference between the inside and the outside of the metal package, and the metal package portion 7 above the dielectric resonator and the dielectric resonance. The interval of the container 2 is changed to reduce the fluctuation.

For example, in the high-frequency oscillator having the structure shown in FIG. 1, when the oscillation frequency of the oscillator rises as the temperature rises, the pressure P2 in the package 3 such as the housing at room temperature of 25 ° C. is kept inside the metal package 5. If it is higher than the pressure P1,
When the temperature rises from 25 ° C, the pressure P2 rises due to the pressure P
Greater than a rise of 1. That is, the pressure difference between the pressure P2 and the pressure P1 increases as the temperature rises. As a result, the force that the metal package 5 receives due to the pressure P2 increases, and the metal package portion 7 above the dielectric resonator 2 deforms into a concave shape and approaches the dielectric resonator 2. This raises the oscillation frequency of the dielectric resonator 2. The result is shown in FIG. According to the present invention, it is understood that the variation of the oscillation frequency due to the temperature rise is relaxed as compared with the conventional example (when P1 = P2).

On the contrary, when the oscillation frequency of the oscillator rises as the temperature rises, the pressure P2 in the package 3 such as the housing is set lower than the pressure P1 in the metal package 5. When the temperature rises from room temperature 25 ° C, the pressure P1
Of the pressure P2 becomes larger than that of the pressure P2, and the pressure difference between the pressure P1 and the pressure P2 increases as the temperature rises. As a result, the force applied to the metal package 5 by the pressure P1 becomes large, and the metal package portion 7 above the dielectric resonator 2 is deformed into a convex shape and is separated from the dielectric resonator 2. As a result, the oscillation frequency of the dielectric resonator 2 is lowered. The result is shown in FIG. According to the present invention, the conventional example (P1 = P2
It is understood that the fluctuation of the oscillating frequency due to the temperature rise is alleviated.

The present invention is not limited to the high frequency oscillator having the structure shown in FIG. 1, and it goes without saying that various modifications can be made. For example, when an oscillator in which a dielectric resonator is used for a resonance circuit is used, if at least the upper part of the dielectric resonator 2 of the metal package 5 is made of a member having reversible deformation characteristics. Of course, the entire metal package 5 may be made of a member having reversible deformation characteristics. Further, the upper part of the dielectric resonator 2 can be formed in a shape that is easily deformed. Note that P1 and P2 are appropriately set according to the deformation characteristic and the temperature characteristic of the dielectric resonator.

[0018]

As described above, according to the present invention, by utilizing the pressure difference, the metal package portion above the dielectric resonator which determines the oscillation frequency is deformed into a concave or convex shape (dielectric resonance). It is possible to move the device closer to or away from the container, and it is possible to reduce the fluctuation amount of the oscillation frequency. Further, the temperature characteristic curve of the oscillation frequency can be changed by arbitrarily selecting the pressure difference between the internal pressure and the external pressure of the oscillator or the material and structure of the metal package.

[Brief description of drawings]

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

FIG. 2 is a diagram illustrating an embodiment of the present invention.

FIG. 3 is a diagram illustrating an embodiment of the present invention.

FIG. 4 is a diagram illustrating an embodiment of the present invention.

FIG. 5 is a temperature characteristic curve of oscillation frequency of the present invention and a conventional example.

FIG. 6 is a temperature characteristic curve of the oscillation frequency of another invention and the conventional example.

FIG. 7 is a cross-sectional view of a conventional high frequency oscillator.

FIG. 8 is a cross-sectional view of another conventional high frequency oscillator.

[Explanation of symbols]

1: MIC substrate, 2: dielectric resonator, 3: package such as housing, 4: different MIC substrate, 5: metal package,
6: Oscillation frequency adjusting screw, 7: Metal package part, 8:
Distance between the metal package on top of the dielectric resonator and the dielectric resonator

Claims (2)

[Claims] 1. A high-frequency oscillator in which an oscillator hermetically sealed with a member having reversible deformation characteristics is further hermetically sealed, wherein the oscillator includes a dielectric oscillator in a resonance circuit, As the oscillation frequency rises from room temperature,
In the case of having the characteristic of lowering, the member is deformed into a concave shape so that the interval between the dielectric resonator and the member above the dielectric resonator becomes narrower, and conversely has the characteristic of increasing the oscillation frequency. In this case, the member is deformed into a convex shape so that the distance between the dielectric resonator and the member above the dielectric resonator becomes wide, and the fluctuation of the oscillation frequency due to the temperature fluctuation of the oscillator is mitigated. A high-frequency oscillator characterized by: 2. The high frequency oscillator according to claim 1, wherein
When the internal pressure and the external pressure of the oscillator are different and the oscillation frequency of the oscillator has a characteristic that the temperature decreases from room temperature as the temperature rises, the internal pressure is set lower than the external pressure, and conversely. A high-frequency oscillator, wherein the internal pressure is set higher than the external pressure when the oscillation frequency has a characteristic of increasing.