JPS6195618A - Temperature compensation oscillator - Google Patents

Abstract

PURPOSE:To reduce the power consumption of a numeral conversion means by detecting a change in the 1st digital signal to conduct a switch and keeping another input digital signal to output of a digital signal. CONSTITUTION:The change in an input signal 102 at application of power is detected by a comparator 22 and a latch circuit 21. The switch 23 is closed by a signal change 202, a power supply 203 is fed to a read only memory 24, from which a signal 204 is outputted. A latch circuit 25 reads the signal 204 to output a digital signal 205 having the value. When a change in the input signal 102 is lost, the switch 23 is opened and the read only memory 24 stops the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature compensated oscillator fi, and more particularly to a digitally controlled temperature compensated oscillator.

[Conventional technology]

Local oscillators used in mobile radio devices are required to have high frequency stability over a wide temperature range and to be compact. A digitally controlled temperature-compensated oscillation device is an oscillation device that can satisfy such requirements. The general structure of the digitally controlled temperature-compensated oscillator is comprised of a temperature detection section, a control section, and an oscillation section.

The temperature detection section detects the ambient temperature and generates a temperature signal, further quantizes this signal and outputs it to the control section as a first digital signal having a first digital value.

The control section includes a numerical conversion means for converting a first digital value into a second digital value (according to a predetermined correspondence relationship) and outputting a second digital signal having the converted value. An example of this numerical value conversion means is a read-only memory (hereinafter referred to as ROM). The ROM stores a second digital value at an address designated by the first digital value), inputs the first digital signal to an address terminal, and outputs a second digital signal. Another example of a numerical value conversion means is one that is completely equipped with a memory that generates a constant of a polynomial for converting a first digital value into a second digital value, and an arithmetic unit that operates on this polynomial (for example, Japanese Patent Laid-Open No. 58 -184809) is also known.

The oscillation section includes a DA converter and a voltage controlled oscillator. A voltage controlled oscillator is constructed by attaching a variable capacitance diode to an oscillator whose oscillation frequency is determined by a crystal resonator or surface acoustic wave element. The DA converter converts the second digital signal, which is the output of the control section, into a voltage signal and outputs it to the voltage controlled oscillator.

A voltage signal is applied to the variable capacitance diode, and the oscillation frequency of the zero voltage controlled oscillator that controls the capacitance value exhibited by the variable capacitance diode changes as the capacitance value changes, so it is controlled by the voltage signal. .

When the ambient temperature changes, the oscillation frequency of the oscillator tends to change depending on the temperature characteristics of the crystal resonator or surface acoustic wave element. At this time, the voltage signal also changes at the same time due to the action of the temperature detection unit 1 control unit and the L)-A converter to compensate for the change in the oscillation frequency, so the oscillation frequency of the voltage controlled oscillator is kept at a constant value of 0 or more. The conventional digitally controlled temperature-compensated oscillator described in 2. performs temperature compensation digitally, so it has high frequency stability over a wide temperature range, and has many digital circuits in its components, making it suitable for IC implementation. Although it has the advantage of being able to be used as a small board, it has the disadvantage of high power consumption because the numerical conversion means is constantly operating.

[Problem that the invention seeks to solve]

The problem to be solved by the invention, in other words, the purpose of the present invention is to provide a digitally controlled temperature compensated oscillator in which the power for operating the numerical converter R is turned on only when the ambient temperature changes, and at other times. By eliminating the above drawbacks, we have developed an IC with excellent frequency stability over a wide temperature range.
The object of the present invention is to provide a temperature-compensated oscillator that is suitable for various applications and has low power consumption.

[Means for solving problems]

The temperature compensated oscillation device of the present invention includes a temperature detection section that detects the ambient temperature and outputs the detection result as a first digital signal having a first digital value; an oscillation unit that outputs a second digital signal having a second digital value corresponding to the digital value of the second digital signal; In the temperature-compensated oscillator, the control section includes:
change detection means for inputting the first digital signal and outputting a change signal of a certain length to the switch means when detecting a change in the first digital value; said switch means for conducting said first digital signal; and numerical conversion means for manually inputting said first digital signal and outputting said third digital signal having said digital value of M2 while power is inputted through said switch means. and a numerical value holding means for inputting the third digital signal, holding the digital signal, and outputting the second digital signal.

〔Example〕

The present invention will be described in detail below with reference to all the drawings showing examples.

FIG. 1 is a block diagram showing an embodiment of the temperature compensated oscillation device of the present invention.

The temperature-compensated oscillator of this embodiment includes a temperature detection section 1, a control section 2, and an oscillation section 3. The temperature detection section 1 detects an ambient temperature and generates a voltage corresponding to the ambient temperature. A temperature sensor 11 that outputs a voltage having a value as a temperature signal 101, and an A-D converter 12 that inputs the temperature signal 101, quantizes it into a first digital value, and outputs it as a first digital signal 102. ing.

The control unit 2 outputs a first digital signal 102 and a change signal 20.
2 is input, and when the value of the change signal 20'2 is the logical value "1°, the value of the first digital signal 101, that is, the first digital value at this time, is read, and the signal 201f having the read value is constantly output. The latch circuit 21 inputs the first digital signal 102 and the signal 201, compares the values of these two signals at a certain period, and when the values of both signals are different, sets the logic value "1" for a certain period of time. Comparator 22 outputs a change signal 202t which takes a logical value of '0' in all other cases.
and a switch 23 which inputs the power supply power 203 from a power source (not shown) and makes the power supply power 203 conductive only when the value of the change signal 202 is a logical value "1". , inputs the first gage digital signal 102,
A loop 0M24 operates only while power supply 203 is supplied through the switch 23 and outputs a signal 204 having a second digital value corresponding to the first digital value, and a signal 204 and a change signal 202. input, change signal 2
When the value of 02 is the logical value "1", the value of the signal 204, that is, the second digital value at this time, is read, and a latch circuit 25 that always outputs a signal having the read value as the second digital signal 205 is fully equipped. ing.

The oscillation unit 3 includes a D-large converter 31 that inputs the second digital signal 205, converts the value into a voltage signal 301, and outputs the voltage signal 301.
and a voltage controlled oscillator 32 which is made up of a crystal oscillator and a variable capacitance diode and outputs an oscillation signal 302 having a frequency controlled by a voltage signal 301t to the outside via a terminal 99.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

FIG. 2 is a flowchart showing the periodic operation of temperature compensation in this embodiment.

The cycle of this operation (the time from step B of one cycle to step B of the next cycle) is such that when the time rate of change of the ambient temperature is maximum, the value of the temperature signal 101 is
(The time that changes by 2 quantization steps) is determined so that it is sufficiently short.

When the temperature compensated oscillator of this embodiment is powered on,
The contents of the latch circuit 21 and the contents of the latch circuit 25 are both #01, and the switch 23 is in the open state (step person). The temperature signal 101 constantly output from the temperature sensor 11 is quantized by the λ-D converter 12, and the A-D converter 12 outputs the first digital signal 102 (step B).

The value of the first digital signal 102 and the value of the signal 201 which is the output of the latch circuit 21 are compared by the comparator 22, and the comparator 22 outputs a change signal 2 of the logic value "1" or the logic value "0".
02 (step (J.

Since the content of the latch circuit 21 is "O'" when the power is turned on, the value of the change signal 202 becomes a logical value of 11' in the first cycle after the power is turned on, and the operating state shifts from step C to step E. In step E, the switch 23 is closed, and the power source 203 is turned on via the switch 23.
It is stamped into OM24, and ROM24 outputs signal 204.

Next, the latch circuit 25 reads the value of the signal 2040 and outputs a second digital signal 205f having that value. Further, the latch circuit 21 receives the first digital signal 10
Read the value of 2 (step P).

When steps E and F are completed, the value of the change signal 202 becomes the logical value "0", the switch 23 returns to the open state, and the R
OM24 stops operating. The launch circuit 21 holds the value of the signal 201 read in step F (this value is equal to the value of the first digital signal 102 in step B).The latch circuit 25 also holds the value read in step F, that is, the value of the first digital signal 102 in step B. 2. The value of the digital signal 205 is held (step G).

The D-magnitude converter 31 converts the second digital signal 205 into a voltage signal 301 and outputs it (step D), and the voltage controlled oscillator 32 outputs an oscillation signal 302 having a frequency controlled by the voltage signal 301.

With this, the first cycle ends, and the second cycle starts after returning to step BK.

Since the change in the ambient temperature is small, and therefore the change in the temperature signal 101 is small, the value of the first digital signal 102 in step B of the second cycle changes from the first cycle to the latch circuit 21.
If the value of the change signal 202 is equal to the value of the signal 201 held in the step C of the second cycle, the value of the change signal 202 becomes the logic value "01".The state of operation changes from step C to step D.
to move to. Since the value of the second digital signal 205 remains unchanged since the first cycle while being held in the latch circuit 25, the voltage value of the voltage signal 301 at step D of the second cycle is also unchanged from its value at step DIC of the first cycle. , therefore, the frequency of the oscillation signal 302 also does not change.

The change in the ambient temperature is large, and therefore the temperature signal 101 changes greatly, and the value of the first digital signal 102 in step B of the second cycle changes from the first cycle to the latch circuit 21.
If the value of the signal 201 is different from that held in the second
The value of the change signal 202 in step C of the cycle becomes a logic value "1" and thereafter follows the same process as from step E to step D of the first cycle. In this case, step D
Since the voltage value of the voltage signal 301 at is different from its value at step DIC of the first cycle, the change in the oscillation frequency of the crystal oscillator constituting the voltage controlled oscillator 32 due to changes in ambient temperature is compensated for and 30
2 frequency is kept constant.

Thereafter, the change in ambient temperature is small and the first digital signal 102
As long as the value of is unchanged from its value in the previous cycle, the operating state repeats steps B, C and D, and the voltage signal 30
The voltage value of 1 remains unchanged from its value in the previous cycle, and the frequency of the oscillation signal 302 is also kept constant. Also, if the ambient temperature changes so much that the value of the first digital signal 102 differs from its value in the previous cycle, the operating state follows steps B-C, E, F, and GD, depending on the change in ambient temperature. Compensate for changes in oscillation signal 3020 frequency.

Now, the time probability that the time rate of ambient temperature takes the maximum value is extremely small, and in most of the operating cycles, step B
, C.D, the ROM 24 during the entire operating time.
The proportion of time that the power is on is extremely small.

Therefore, the ratio of the power consumed by the ROM 24 to the time average value of the power consumed by the temperature compensated oscillator of the embodiment shown in FIG. 1 is small.

``Appetizer Ll/'' Explanation in the Meo Iji Oshishi: The temperature-compensated oscillator of the present invention is a temperature-compensated oscillator of the digital control section, in which the power supply for operating all the numerical conversion means is activated when the ambient temperature changes. Since the power consumption of the numerical conversion means occupies a small proportion of the time average value of the total power consumption, the temperature compensated oscillator of the present invention can be used. It is possible to obtain a temperature-compensated oscillator with low power consumption and excellent gastric wave number stability over a wide temperature range. The device used has the effect of making it possible for people with small hearing loss0

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the temperature compensated oscillation device of the present invention. FIG. 2 is a flowchart showing the operation of the embodiment shown in FIG. 1... Temperature detection section, 2... Control section, 3
...Oscillator... Attorney = Uchihara Kubi 1, Kamo 1. - -ta? Shino [n■ 2nd I￥
1

Claims (1)

[Scope of Claims] A temperature detection section that detects ambient temperature and outputs the detection result as a first digital signal having a first digital value; a control unit that outputs a second digital signal having a first digital value corresponding to the temperature; and an oscillation unit that receives the second digital signal and outputs an oscillation signal having a frequency controlled by the second digital signal. In the compensated oscillation device, the control section includes change detection means for inputting the first digital signal and outputting a change signal of a certain time length to the switch means when detecting a change in the first digital value; the switch means which conducts the power supply only while the signal is input; and the switch means which receives the first digital signal and has the second digital value while the power supply power is input through the switch means. Temperature compensated oscillation characterized by comprising: a numerical value conversion means for outputting the third digital signal; and a numerical value holding means for inputting the third digital signal, holding its value, and outputting the second digital signal. Device.