JPH0296406A - Temperature compensation crystal oscillator - Google Patents

Abstract

PURPOSE:To highly maintain the frequency stability by converting the oscillation frequency of one side oscillating circuit to the compensation voltage responding to the temperature and controlling the oscillation frequency of other side oscillating circuit by the compensation voltage. CONSTITUTION:A constant temperature bath 8 accommodates first and second oscillating circuits 1 and 7, a circuit 1 AT-cuts a crystal oscillator 2, and the temperature characteristic is made into a cubic curved line and the temperature slope from the minimum value is made into Appm/ deg.C. On the other hand, the circuit 7 makes a crystal oscillator 11 into a Y cut which is made into the linear curved line by the temperature characteristic. A frequency voltage converting circuit 9 converts the oscillation frequency of the circuit 7 to the compensation voltage and controls the capacity value of a variable capacity diode 10. The temperature characteristic of the circuit 7, since the temperature slope is steep, responds to the temperature in the bath 8 more sensitively than the circuit 1. Consequently, the micro frequency change due to the temperature change in the bath 8 of the circuit 1 is compensated and the oscillation frequency can be maintained to the high stability.

Description

[Detailed Description of the Invention] (Industrial Utilization) The present invention uses a constant temperature bath. l [l compensated crystal oscillation v
:4 (hereinafter referred to as "temperature lfl in oscillator") is used as a field of application, and the present invention relates to a temperature-compensated oscillator that takes advantage of frequency stability due to minute temperature changes in a thermostatic oven.

(Background of the invention) The Li degree compensated oscillation bud is caused by the frequency temperature C caused by the crystal resonator.
7 characteristics (hereinafter referred to as temperature characteristics) and provides a stable frequency, it is suitable for dynamic environments! Rivers are frequent. Especially when high stability is required: ζ houses the crystal oscillator in a constant temperature bath to keep its operating temperature constant.

(Conventional example) Figure 4: Temperature to explain a conventional example of this kind? It is a schematic diagram of the l11 compensation 1a device.

The oscillation circuit 1 is formed by using a crystal resonator 2 as an oscillator to form, for example, a Colpitts network (not shown).

Crystal rM! The r'j element 2 is made of, for example, an AT-cut thickness shear vibrator. In this type of device, the crystal oscillator is
For this reason, the temperature characteristic is assumed to be a cubic curve with an inflection point near normal temperature as shown in FIG.

In the constant temperature bath 3, for example, a heat filter (not shown) such as a heat filter 514 is wound. A temperature sensing element 5 such as a thermistor is installed in the constant temperature bath. Then, the temperature inside the tank reaches the temperature detected by the humidity sensing element 5, and the control circuit 6 operates to keep the temperature inside the tank constant. The temperature inside the tank is set to the minimum value of the temperature characteristics (around 70° C.), where the frequency change is the least. Therefore, in such a device, the oscillation frequency near the minimum value of the temperature characteristic is set as the reference frequency 10, and the frequency stability is set to within 1 ppm to supply all highly stable frequencies.

(Disadvantages of the prior art) However, the above Ji? Temperature of formation? In the case of a compensation oscillator, for example, when the standard temperature range is -30 to 70℃ and compensation is performed over a wide range, even if the chamber temperature is set to 70℃,
It is shown in Figure 6. In reality, the temperature varies by 11°C due to manufacturing considerations for constant temperature baths. Therefore, in such a case, the oscillation frequency changes from 1° to f with a change amount of Δf in response to the temperature inside the tank, and there is a problem that a high degree of frequency stability cannot be maintained.

(Objective of the invention) The present invention uses a constant temperature bath that maintains high frequency stability. The purpose is to provide ln IFF Q Elσ Alliance.

(Lower part of the solution) The present invention calculates the temperature gradient of the frequency temperature characteristic by A/℃p rI
At least these oscillators of the voltage-controlled first oscillation circuit and the second oscillation circuit whose temperature gradient was 07°C ((rI7, B>8) and 17°C) were kept at a constant temperature of 1t.
"l", and the oscillation frequency of the second oscillation circuit is kept constant at 2!1.
．． The solution is to convert the temperature inside the tank (ζ) into a compensated voltage of +11 and control the wave number of the first optical oscillation circuit from this compensation voltage.Hereinafter, one of the aspects of the present invention A conventional example will be explained.

(Example) The ftS1 diagram illustrates a conventional example of the present invention at 411 degrees? 1
11 is a schematic diagram of an eleventh compensation oscillator; FIG. Note that the same parts as in the previous conventional example are given the same numbers 17, and the explanation thereof will be simplified.

The temperature compensated oscillation plate includes a first oscillation circuit 1 and a second eye development circuit 7.
, a high temperature tank 8, and a frequency voltage (f...V) conversion circuit 9
It consists of

First redundant cycle: In Ir11, the crystal resonator (oscillator) 2 is AT-cut as in the fft described above, and its temperature characteristic is a cubic curve (curve A in FIG. 2). Then, the oscillation frequency at 70°C (reference temperature), which is the minimum value of the temperature characteristics, is
Let it be to. In addition, the temperature gradient from the minimum value to Δp
p m / ”C (absolute value of fllL).

Then, a variable voltage 'f' is applied between the crystal oscillator and the ground potential.
Connect the ¥A guide wire 10 to make it a voltage control type. .

The second oscillation circuit 7 is blind to the first oscillation circuit! 11 is a Korpi-Sotsu network not shown in the figure. Then, the crystal resonator 11 serving as an oscillator is made into a Y-cut whose temperature characteristic is a linear curve, and its temperature gradient is IS p p m / °C ((Il
l, n>A) (Figure 2 curve opening).

The high temperature tank 8 accommodates the first and second light range circuits 1.7, is equipped with a temperature sensing element 5, and is controlled to control the temperature inside the tank by a control circuit 6 to 70°C.
Set to .

The frequency-voltage conversion circuit 9 changes the oscillation frequency of the second oscillation circuit 7? ln fft ftf voltage V, and is applied to the a node of the voltage variable diode 10. Compensation voltage V,
is shown in No. 314. 1. Oscillation frequency (reference frequency re) of the second oscillation circuit 7 at the reference temperature (70°C)
Let be the reference voltage V. Then, the temperature change in the thermostatic chamber (
In response to the frequency change of the second oscillation circuit 7 caused by The compensation voltage characteristic is set as the characteristic.

In this case, the temperature characteristic of the second oscillation circuit 7 has a steep temperature gradient, so it responds more sensitively to the bath temperature than the first oscillation circuit 1 (i.e., for a change of 1 degree, d). (high detection accuracy). Then, the oscillation frequency of the second oscillation circuit 7 (
The nnff1 voltage v5 based on the absolute value of the amount of change is Ii
■Change the capacitance value of the transformer resistance diode 1o. j7 Therefore, what is the slight frequency change due to the temperature change inside the tank of the first oscillation circuit 1? lrl compensation to maintain the oscillation frequency at high stability.

(Other matters) Note that in the embodiment described in item 1, the first and second oscillation circuits 1.7 are housed in a constant temperature oven, and only the crystal oscillator 2.11, which is the main cause of temperature characteristics, is housed. The oscillation circuit may be housed in a thermostatic oven, and the key point is that the oscillation circuit's stiffness characteristic is determined by housing the deviated portion in the thermostatic oven.

Although only one constant temperature bath 8 is used, if they have the same characteristics, even if the first and second oscillation circuits 1f5's7 are housed in four separate chambers, the number of chambers 8 will be one. Also, what about the first oscillation circuit 1? W
S degree tl f'i 't: The second oscillation circuit 7 is a quadratic curve A'r cut, and the second oscillation circuit 7 is a linear curve Y cut crystal oscillator. Of course, it is sufficient if the temperature characteristics of the piezoelectric material are steeper than those of the first oscillation circuit (for example, even if it is made of another piezoelectric material).

(Effects of the Invention) The present invention reduces the temperature gradient of the frequency temperature characteristic to 47°C11 i
At least these oscillators, ie, crystal resonators, of a voltage-controlled first oscillation circuit whose temperature gradient is R/l (([11,,B〉8)] are placed in a thermostatic chamber. The oscillation frequency of the second oscillation circuit is converted into a compensation voltage in response to the temperature inside the thermostatic chamber, and the oscillation frequency of the first oscillation circuit is controlled by the compensation voltage, so the frequency stability can be improved to a high degree. It is possible to use a compensation oscillator for X+ for use in a constant temperature bath maintained at a constant temperature.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a temperature-compensated generator illustrating an embodiment of the present invention. FIG. 2 is a temperature characteristic diagram of the first and second oscillation circuits in one embodiment of the present invention. , FIG. 3 is a compensation voltage characteristic diagram in one embodiment of the present invention. FIG. 4 is a schematic diagram of a temperature compensated oscillator to explain a conventional example, FIG. 5, and FIG. 3 are temperature characteristic diagrams of a brush oscillation circuit. 1.7 - Oscillation circuit, 2.11...Crystal resonator, 3.
8. Constant temperature chamber, 4. Heat wire, 5. Temperature sensing element, 6. Control circuit, 9. Frequency voltage conversion circuit, 10. Voltage variable container gayode. Information 3 diagram*2tx

Claims (2)

[Claims] (1) A voltage-controlled first oscillation circuit with a temperature gradient of frequency turbidity characteristics of A/°C ppm and a second oscillation circuit with a temperature gradient of B/°C (however, B>A) are placed in a thermostatic chamber. A temperature-compensated crystal, characterized in that the oscillation frequency of the second oscillation circuit is converted into a compensation voltage responsive to the temperature inside the thermostatic oven, and the oscillation frequency of the first oscillation circuit is controlled by the compensation voltage. oscillator. (2) Serves as an oscillator for a voltage-controlled first oscillation circuit with a temperature gradient of frequency-temperature characteristics of A/°C ppm and a second oscillation circuit with a temperature gradient of B/°C (however, B > A). The crystal resonator is housed in a thermostatic oven, the oscillation frequency of the second oscillation circuit is converted into a compensation voltage responsive to the temperature inside the thermostatic oven, and the oscillation frequency of the first oscillation circuit is controlled by the compensation voltage. Features a temperature compensated crystal oscillator.