JPH0535340A - Temperature compensating circuit - Google Patents

Abstract

PURPOSE:To provide the temperature compensating circuit which can obtain an arbitrary temperature compensating characteristic. CONSTITUTION:The forward voltage of a diode 1 is converted to a digital value by an A/D converter 1 and fetched into a CPU 2 and at the CPU 2, this digital signal is compared with the temperature compensating characteristic value previously stored in a ROM 3. Then, a temperature compensating digital, signal suitable for the desired temperature compensating characteristic of a circuit 20 to be compensated with the temperature is calculated and generated, and this temperature compensating digital signal is converted into a temperature compensating analog signal by a D/A converter 4 and supplied to the circuit 20 to be compensated with the temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature compensation circuit which outputs an analog temperature compensation signal to a temperature compensation circuit.

[0002]

2. Description of the Related Art Conventionally, this type of temperature compensation circuit is a pure analog type which uses a thermistor and a diode.
An example thereof is shown in FIG.

The temperature compensating circuit shown in FIG. 6 utilizes the temperature characteristic of the diode D1 whose forward voltage decreases as the temperature rises, as shown in FIG. 7, and the forward voltage of this diode D1 is used. In addition to the input terminal a of the comparator 1,
In the comparator 1, the forward voltage of the diode D1 is compared with the reference voltage VR applied to the input terminal b, and the comparator 1
The temperature of the temperature compensated circuit 10 is compensated by supplying the comparative output of (1) to the temperature compensated circuit 10.

However, in this conventional temperature compensating circuit, the compensation characteristic conforms to the forward voltage characteristic with respect to the temperature of the diode as shown in FIG. 8, and an arbitrary compensation characteristic cannot be obtained.

[0005]

As described above, the conventional temperature compensating circuit is composed of an analog circuit using a thermistor or a diode, so that the degree of freedom of the temperature compensating characteristic is limited, and an arbitrary compensating characteristic can be obtained. I couldn't get it.

Therefore, the present invention has been made in view of this problem, and an object thereof is to provide a temperature compensation circuit which can obtain an arbitrary temperature compensation characteristic.

[0007]

In order to achieve the above object, the present invention provides an input means for converting a forward voltage of a diode which changes according to a temperature change into a digital signal and inputting it, and a predetermined temperature compensation characteristic. Storage means for storing the value,
The temperature-compensated digital signal generating means for comparing the digital signal input by the input means with the temperature-compensated characteristic value stored in the storage means to generate a temperature-compensated digital signal, and the temperature-compensated digital signal generation means. And an output means for converting the temperature-compensated digital signal into an analog signal and outputting the analog signal to the temperature-compensated circuit.

[0008]

The forward voltage of the diode, which changes according to the temperature change, is converted into a digital signal by the input means and input, and this input digital signal is compared with a predetermined temperature compensation characteristic value stored in the storage means in advance. Then, a temperature compensation digital signal is generated, and the temperature compensation digital signal is converted into a temperature compensation analog signal by the output means and output to the temperature compensated circuit. With this configuration, an arbitrary temperature compensation characteristic can be realized according to the temperature compensation characteristic value stored in the storage means.

[0009]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of the temperature compensation circuit of the present invention. In FIG. 1, the temperature compensating circuit of this embodiment is an analog-digital converter (A / D converter) 1 for analog-digital converting the forward voltage of the diode D1, and a central operation for executing an operation for generating a temperature-compensating digital signal. Processor (C
PU) 2, a read only memory (ROM) 3 for storing a predetermined temperature compensation characteristic value in advance, a temperature compensation digital signal calculated by the central processing unit 2 is converted into a temperature compensation analog signal, and the temperature compensated circuit 20 And a digital-analog converter (D / A converter) 4 for outputting to.

In this embodiment, the forward voltage of the diode D1 which changes according to the temperature change, that is, the analog signal corresponding to the potential at the point a in FIG. 1 is input to the A / D converter 1, where the analog signal is input. It is converted into a digital signal corresponding to the signal and is taken into the CPU 2. CP
In U2, this digital signal is compared with the temperature compensation characteristic value stored in advance in the ROM 3, and the temperature compensated circuit 20
The temperature-compensated digital signal suitable for the desired temperature-compensated characteristic of is calculated and generated. The temperature-compensated digital signal arithmetically generated by the CPU 2 is added to the D / A converter 4, converted into a temperature-compensated analog signal in the D / A converter 4, and supplied to the temperature-compensated circuit 20.

FIG. 2 shows an example of the temperature compensation analog signal output from the temperature compensation circuit when the compensated circuit 20 to be controlled by the temperature compensation circuit is a crystal oscillation circuit. The compensation characteristic value and the analog signal are shown in relation to the output of the A / D converter 1.

Here, in the ROM 3, as shown in FIG. 3, the output voltages VD1, VD2, VD of the diode D1 are stored in advance.
3, VD4, ... Desired temperature compensation characteristic values, in this case, digital output values V1, V2, V3, V4 corresponding to the temperature compensation characteristic values of the crystal oscillation circuit which is the compensated circuit 20.
Is the output voltage VD1, VD2, VD of the diode D1
A table stored corresponding to 3, VD4, ... Is stored, and the CPU 2 arithmetically generates a desired temperature compensation digital signal based on this table.

Here, for example, if the temperature is T1 as shown in the table of FIG. 3, the forward voltage of the diode D1 becomes VD1, and at this time, the CPU 2 outputs the digital signal V1. The digital signal V1 output from the CPU 2 is converted into an analog voltage by the D / A converter 4 and output to the crystal oscillation circuit which is the temperature compensated circuit 20. Thereby, for example, the voltage frequency control circuit of the crystal oscillation circuit is controlled, and the temperature compensation of the oscillation frequency of the crystal oscillation circuit is performed.

Similarly, when the temperatures are T2, T3, T
4, the forward voltage of the diode D1 becomes VD2, VD3, VD4 ,.
U2 outputs digital signals V2, V3, V4, ... And the digital signal output from the CPU2 is D
Each is converted into an analog voltage by the / A converter 4,
It is supplied to the crystal oscillation circuit that is the compensated circuit 20. As a result, temperature compensation of the oscillation frequency of the crystal oscillation circuit is performed.

In the above embodiment, the A / D converter 1, the CPU 2, the D / A converter 4, and the ROM 3 can be integrated and integrated, which can reduce the temperature compensation circuit.

FIG. 4 shows another embodiment of the temperature compensation circuit of the present invention.

In the embodiment shown in FIG. 4, the circuit shown in FIG.
It is configured by adding a converter 5. In the case of this embodiment, as shown in FIG. 5, the ROM 11 stores a table in which digital output values which are a plurality of temperature compensation characteristic values according to the output voltage of the diode D1 are stored.

According to this structure, one temperature compensating circuit can compensate the temperature of a plurality of temperature compensated circuits, in this case, the temperature compensated circuits 20 and 30.

When it is desired to further increase the number of compensated circuits, the number of output ports of the CPU 9 is increased as shown in the table of FIG. 5 (in this case, output ports 8, 9, ...), and the CPU 9, The output value of the CPU 9 corresponding to the forward voltage of the diode D1 is output by controlling each output port with D / A connected to this output port.
The number of converters should be increased.

Further, the A / D converter 1, the CPU 9 and the D
It is possible to integrate the A / A converters 4 and 5 and the ROM 11 into an integrated circuit, which makes it possible to reduce the size of the temperature compensation circuit.

Further, in this embodiment, as shown in FIG.
Although it is configured to use U2, it is not limited to this.
Instead of using the CPU 2, the contents of the table of the ROM 3 may be directly read by the digital signal output from the A / D converter 4.

If the CPU 2 is used and the ROM 3 is also used to store data for interpolation calculation, CP
Interpolation calculation processing can be performed by U2, and fine temperature compensation can be performed.

[0024]

As described above, according to the temperature compensating circuit of the present invention, the temperature compensation of the temperature compensated circuit is performed with an arbitrary temperature compensating characteristic according to the temperature compensating characteristic value previously written in the ROM. It can be carried out. Further, if a plurality of temperature compensation characteristic values for the forward voltage of the diode are written in the ROM in advance, temperature compensation can be performed for a plurality of circuits to be compensated.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a temperature compensation circuit of the present invention.

FIG. 2 is a diagram showing an example of temperature compensation characteristics when the compensated circuit according to FIG. 1 is a crystal oscillation circuit.

FIG. 3 is a diagram showing an example of a table stored in a ROM of the embodiment shown in FIG.

FIG. 4 is a block diagram showing another embodiment of the temperature compensation circuit of the present invention.

5 is a diagram showing an example of a table stored in a ROM of the embodiment shown in FIG.

FIG. 6 is a circuit diagram showing a conventional temperature compensation circuit.

FIG. 7 is a diagram showing a temperature forward voltage characteristic of a diode.

8 is a diagram showing temperature compensation characteristics of the conventional circuit shown in FIG.

[Explanation of symbols]

 1 A / D converter 2, 9 CPU 3, 11 ROM 4,5 D / A converter 20, 30 Compensated circuit 6, 7, 8 CPU9 output port D1 diode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hidetaka Ogawa 3-3-9 Shimbashi, Minato-ku, Tokyo Toshiba Abu E. Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. Input means for converting a forward voltage of a diode, which changes according to temperature change, into a digital signal and inputting the digital signal, storage means for storing a predetermined temperature compensation characteristic value, and A temperature-compensated digital signal generating means for generating a temperature-compensated digital signal by comparing the digital signal input by the input means with the temperature-compensated characteristic value stored in the storage means; And a temperature compensating circuit for converting the digital signal to an analog signal and outputting the analog signal to the temperature compensated circuit.