JP2000013139A - Temperature compensated oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce fluctuation in an oscillation frequency due to dispersion in a temperature characteristic of a dielectric resonator in a local oscillation circuit such as an LNB using the dielectric resonator. SOLUTION: A temperature compensation circuit 6a is provided between a drain (D) terminal of an oscillation FET and a DC power supply Vo, a drain- source voltage of the FET is changed in response to fluctuation in ambient temperature to compensate the fluctuation in the oscillated frequency. This temperature compensation circuit 6a is applied when the frequency gets higher as a temperature characteristic of the dielectric resonator is increasing. The temperature compensation circuit 6a uses a thermister Rta to decrease a drain voltage Vd when ambient temperature rises resulting in decreasing the oscillating frequency, and to increase the drain voltage when ambient temperature falls resulting in increasing the oscillating frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature-compensated oscillation device, and more particularly to temperature compensation of an oscillation frequency of a local oscillation circuit in an LNB (low noise block) used for a satellite broadcast receiving antenna. .

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a main portion of an example of a local oscillation circuit in a conventional LNB, in which a main portion of a local oscillation circuit formed on a microstrip line type circuit board is viewed from above. Is drawn. Further, resistors, capacitors, coils, and the like are symbolized and drawn. In FIG. 1, reference numeral 1 denotes an FET (field effect transistor), 1a denotes a drain terminal (leg), 1b denotes a gate terminal (leg), and 1c denotes a source terminal (leg). 2, 3, 4
Is a conductor pattern for soldering the FET1, which is for the drain terminal, the gate terminal, and the source terminal in order. Reference numeral 5 denotes a dielectric resonator, and Vo denotes a DC voltage (power supply). As shown in the figure, the local oscillation circuit shown in the figure uses the dielectric resonator 5 as one component of oscillation formation.
An oscillation circuit formed of ET1 or the like and the dielectric resonator 5 are mainly coupled via the conductor pattern 3 (for a gate terminal) to oscillate a predetermined frequency (for example, a 10 GHz band). . The oscillation frequency is determined based on each constant of the oscillation circuit formed by the FET 1 and the like, the characteristics of the dielectric resonator 5, the distance between the dielectric resonator 5 and the conductor pattern, the shape and size of the shield case, and the like. Set. The oscillation output is taken from the source terminal 1c. Note that coil Ld and capacitor
The circuit of Cd and the coil Ls and the capacitor Cs is a low-pass filter for removing unnecessary high-frequency components.

On the other hand, the temperature characteristic of the oscillation frequency in this local oscillation circuit is a combination of the temperature characteristic of the oscillation circuit formed by the FET 1 and the like and the temperature characteristic of the dielectric resonator 5. FIG. 3A shows an example of the temperature characteristic of the dielectric resonator 5, and shows the relationship between the ambient temperature and Δf / fo. In addition,
fo is a frequency at a temperature of 25 ° C., and Δf is a fluctuation frequency. As this temperature characteristic, it is possible to produce various characteristics. Further, the temperature characteristic of the oscillation circuit formed by the FET 1 and the like is generally a characteristic having a negative temperature coefficient (the oscillation frequency decreases as the temperature rises). Therefore, conventionally, the temperature characteristic of the dielectric resonator 5 is set so that the synthesis of the temperature characteristic of the oscillation circuit formed by the FET 1 and the like and the standard temperature characteristic of the dielectric resonator 5 is minimized as the total frequency fluctuation. Had been selected.

[0004]

However, the temperature characteristics of the dielectric resonator 5 vary with respect to the standard characteristics. As described above, conventionally, the temperature of the dielectric resonator 5 is set such that the synthesis of the temperature characteristic of the oscillation circuit formed by the FET 1 and the like and the standard temperature characteristic of the dielectric resonator 5 is minimized as the total frequency fluctuation. Although the characteristics (type) are selected, the temperature characteristics vary and the total frequency fluctuation increases. Therefore, conventionally, an allowable range has been provided for the variation in the temperature characteristics of the dielectric resonator 5 to prevent an increase in the total frequency fluctuation. On the other hand, even if the variation in the temperature characteristics of the dielectric resonator 5 is somewhat large, there is a demand that the variation can be used properly by devising the circuit side. When this requirement is satisfied, it is possible to prevent the dielectric resonator from being unusable or discarded due to exceeding the allowable range, and to contribute to effective utilization of resources. The present invention has been made in view of the above demands, and has as its object to provide a temperature-compensated oscillator that compensates for variations in temperature characteristics of a dielectric resonator on a circuit side.

[0005]

According to the present invention, there is provided an oscillation device comprising a dielectric resonator provided near an oscillation circuit using an FET (field effect transistor). Provide temperature compensation means in between,
The FE is controlled by the temperature compensating means in accordance with a change in the ambient temperature.
An object of the present invention is to provide a temperature-compensated oscillator in which the voltage between the drain and the source of T is changed by the temperature compensating means to compensate for oscillation frequency fluctuation.

Further, the temperature compensating means reduces the voltage between the drain and the source of the FET with respect to an increase in the ambient temperature. Further, the temperature compensating means has a first resistor connected at one end to the DC power supply, another end connected to the drain terminal side of the FET, and one end connected to the other end of the first resistor. A second resistor having the other end grounded;
And a thermistor connected in parallel.

Alternatively, the temperature compensating means increases the voltage between the drain and the source of the FET with respect to an increase in the ambient temperature. A first resistor having one end connected to the DC power source and the other end connected to the drain terminal of the FET, and a thermistor connected in parallel with the first resistor; And a second resistor having one end connected to the other end of the first resistor and the other end grounded.

[0008]

Embodiments of the present invention will be described below with reference to the drawings based on embodiments. FIG. 1 is a main part configuration diagram showing one embodiment of the temperature compensated oscillation device according to the present invention, and FIG. 2 is a main part configuration diagram showing another embodiment of the temperature compensated oscillation device according to the present invention. 4A and 4B show a local oscillation circuit in the LNB as in FIG. The difference between FIG. 1 and FIG. 2 indicates that the configuration is properly used depending on the variation of the temperature characteristics of the dielectric resonator 5. Also, the way of drawing both figures is the same as that of FIG. 4, and the same parts as those of FIG. 4 are denoted by the same reference numerals. Also, in FIG. 3, (A) is a standard temperature characteristic diagram of the dielectric resonator, (B) is a state diagram of variation in the temperature characteristic of the dielectric resonator, and (C) is an oscillation circuit formed by the FET 1 and the like. FIG. 2 is an oscillation characteristic diagram illustrating a relationship between an oscillation frequency and a voltage between a drain and a source, and is an example for explaining FIG. 1.

1 and 2, reference numerals 6a and 6b denote temperature compensation circuits, R1a and the like denote resistors, and Rta and Rtb denote thermistors. The basic operation of the other parts except for the temperature compensation circuits 6a and 6b is the same as in FIG. That is, the dielectric resonator 5 is used as a component of the oscillation formation, and the oscillation circuit formed by the FET 1 and the like and the dielectric resonator 5 are mainly coupled via the conductor pattern 3 (for the gate terminal), and A frequency (for example, a 10 GHz band) is oscillated. The oscillation output is taken from the source terminal 1c. Further, as described above, the temperature characteristic of the oscillation frequency in the local oscillation circuit is a combination of the temperature characteristic of the oscillation circuit formed by the FET 1 and the like and the temperature characteristic of the dielectric resonator 5. In this case, the temperature characteristics of the dielectric resonator 5 are based on the standard characteristics (an example) shown in FIG.

The temperature characteristics vary, and an example is shown in FIG. In the figure, FIG.
And the temperature characteristics due to variations. Hereinafter, they are referred to as type, type, and type. Here, when the type and the type are compared with the type, it can be said that the type has a general tendency that the frequency rises due to the temperature rise, and the type has the general tendency that the frequency decreases due to the temperature rise. The present invention compensates for this tendency by temperature. The state of the variation is usually known in advance for each individual dielectric resonator. This is based on attaching data on the side where the dielectric resonator is manufactured or measuring it on the side using it.

On the other hand, in the oscillation circuit formed by the FET 1 and the like, the relationship between the drain-source voltage and the oscillation frequency is as shown in FIG. It is assumed that the drain voltage Vd is a point shown in FIG. Therefore, by using the characteristics of FIG. 3C, it is possible to perform temperature compensation for variations in the temperature characteristics of the dielectric resonator 5. For example, when the temperature characteristic of the dielectric resonator 5 varies, the temperature compensation circuit is configured as shown in FIG. With this configuration, when the ambient temperature increases, the resistance value of the thermistor Rta decreases, and the combined resistance value with the resistor R2a also decreases. As a result, the voltage dividing ratio of the DC voltage Vo by the resistor R1a decreases, and the drain voltage Vd decreases. As a result, the oscillation frequency is lower than that in FIG. 3 (C), and the temperature is compensated for the variation in type. When the ambient temperature decreases, the operation is reversed, and the temperature is similarly compensated.

On the other hand, when the temperature characteristic of the dielectric resonator 5 varies, the temperature compensation circuit is configured as shown in FIG. With this configuration, when the ambient temperature increases, the resistance value of the thermistor Rtb decreases, and the combined resistance value with the resistor R1b also decreases. As a result, the division ratio of the DC voltage Vo by the resistor R2b increases, and the drain voltage Vd increases. As a result, the oscillation frequency is increased as shown in FIG. 3C, and the temperature is compensated for the variation in type. When the ambient temperature decreases, the operation is reversed, and the temperature is similarly compensated. From the above,
In an actual circuit design, the characteristics of the thermistor Rta or Rtb and each resistance value such as R1a are set according to the variation type of the temperature characteristics of the dielectric resonator 5 so that the two cancel each other out to the maximum. When the temperature characteristics are standard (type), the thermistor Rta or R
tb need not be provided.

[0013]

As described above, according to the present invention, even when the temperature characteristics of the dielectric resonator, which is a component of the oscillation circuit, vary, the temperature is compensated, and the oscillation frequency changes with respect to the change in the ambient temperature. Reduce variability. As a result,
Dielectric resonators that could not be used because the variation in temperature characteristics exceeded the allowable range can also be used,
Effective utilization of resources is promoted. Further, the configuration of the temperature compensation circuit itself is simple, and there is little effect on space and cost. From the above, it can be said that the present invention can contribute to an improvement in performance of an oscillation device that oscillates microwaves using a dielectric resonator, such as a local oscillation circuit of an LNB (low noise block).

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram showing one embodiment of a temperature compensated oscillation device according to the present invention.

FIG. 2 is a main part configuration diagram showing another embodiment of the temperature compensated oscillation device according to the present invention.

FIG. 3A is a standard temperature characteristic diagram of a dielectric resonator,
(B) is a state diagram of variation in temperature characteristics of the dielectric resonator,
(C) is the drain of the oscillation circuit formed by FET1 and the like.
FIG. 5 is an oscillation characteristic diagram showing a relationship between an oscillation frequency and a source-to-source voltage.

FIG. 4 is a main part configuration diagram showing an example of a conventional oscillation device.

[Explanation of symbols]

 Reference Signs List 1 FET 1a Drain terminal (leg) 1b Gate terminal (leg) 1c Source terminal (leg) 2, 3, 4 Conductor pattern 5 Dielectric resonator 6a, 6b Temperature compensation circuit R1a, R2a, R1b, R2b Resistors Rta, Rtb Thermistor Ld, Ls coil Cd, Cs capacitor

Claims (5)

[Claims] 1. An oscillation device comprising a dielectric resonator provided near an oscillation circuit using an FET (field effect transistor), wherein a temperature compensating means is provided between a drain terminal of the FET and a DC power supply; A temperature-compensated oscillation device characterized in that the temperature compensating means changes the voltage between the drain and the source of the FET according to the fluctuation of the ambient temperature by the temperature compensating means to compensate for the oscillation frequency fluctuation. . 2. The temperature-compensated oscillation device according to claim 1, wherein said temperature compensating means changes so as to decrease a voltage between a drain and a source of the FET in response to an increase in ambient temperature. . 3. A first resistor having one end connected to the DC power supply and the other end connected to the drain terminal side of the FET, and one end connected to the other end of the first resistor. 3. A temperature compensator according to claim 1, comprising a second resistor connected to the second resistor and the other end grounded, and a thermistor connected in parallel with the second resistor. Type oscillator. 4. The temperature-compensated oscillation device according to claim 1, wherein said temperature-compensating means changes so as to increase the voltage between the drain and the source of the FET as the ambient temperature rises. . 5. A first resistor having one end connected to the DC power supply and the other end connected to the drain terminal of the FET, and a temperature compensator connected in parallel with the first resistor. 5. The temperature compensator according to claim 1, wherein the thermistor comprises a second resistor having one end connected to the other end of the first resistor and the other end grounded. Type oscillator.