JPS63244904A - Digital control temperature compensation type quartz oscillator - Google Patents

Abstract

PURPOSE:To realize the high accuracy of an oscillation frequency characteristic, by providing an operation control part which replaces the number of pulses of a temperature sensor in a prescribed period by a prescribed multiple value and supplies it to a sequential memory part as the signal of address designation, CONSTITUTION:A digital control temperature compensation type quartz oscillator 10 is constituted of a voltage controlled quartz oscillator 1, a temperature sensor part 2, a reference oscillator 3, the sequential memory part 4, the operation control part 5, and a D/A converter 6. And the quartz oscillator 1 consists of a quartz resonator 7 that is an oscillation source and an oscillation circuit, etc., and performs oscillation with a prescribed frequency, and the temperature sensor part 2 detects a temperature in the neighborhood of the quartz oscillator 1. Also, the reference oscillator 3 decides a reference time to separate a temperature count signal (b) outputted from the temperature sensor part 2 at every prescribed period. And the operation control part 5 replaces the temperature count signal (b) outputted from the temperature sensor part 2 in the period decided by the reference oscillator 3 by an address designation signal (d) corresponding to the data allocation of the memory part 4, then, supplies it to the memory part 4.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a digitally controlled temperature compensated crystal oscillator (hereinafter abbreviated as DTCXO) that digitally compensates for the temperature of a crystal oscillator whose oscillation frequency changes with temperature changes. ) regarding.

(Prior Art) In recent years, crystal oscillators have been required to be highly accurate and compact as oscillation means for communication equipment, OA equipment, industrial measurement equipment, and the like.

By the way, the crystal oscillator, which is the oscillation source of the crystal oscillator, has
Since the resonant frequency changes with respect to the ambient temperature, crystal oscillators that utilize this change need to detect the temperature and compensate for the oscillation frequency characteristics.

FIG. 4 is a conventional DTC,XO block circuit diagram.

The above-mentioned DTCXO 50 consists of a thermistor and the like, and includes a temperature sensor section 51 that outputs a voltage value corresponding to the ambient temperature, an A/D converter 52 that converts the analog signal that is the voltage value into a digital signal, and a digitization converter. a D/A converter 54 that converts temperature compensation data into an analog signal based on a signal related to temperature;
A voltage controlled crystal oscillator 55 whose oscillation frequency is changed according to the output voltage of the crystal oscillator 55.

As a result, a change in ambient temperature is detected by the temperature sensor section 51, temperature compensation data regarding the optimum voltage value to be applied to the crystal oscillator 55 is outputted from the memory section 53 with respect to the detected temperature, and the oscillation frequency of the crystal oscillator 55 is changed. Temperature compensation was performed.

[Prior art and its problems]

However, the above-mentioned DTCXO50 has a temperature sensor section 5.
When the detected voltage value of 1 is digitized by the A/D converter 52, it is derived as a parallel several-bit signal and outputted to a plurality of memory unit input terminals as a parallel address designation signal. For this reason, the wiring around the memory section 53 becomes complicated, and the shape of the memory section 53 becomes large. Furthermore, the temperature sensor section 51SA/D converter 52 and D
There is a limit to the integration of the /A converter 53, and the DTCXO
It was extremely difficult to house the 50 in one casing and downsize it.

[Object of the present invention]

The present invention was devised in view of the above-mentioned problems, and its purpose is to maintain high precision oscillation frequency characteristics by performing temperature compensation through digital processing based on temperature pulses appearing as digital signals, and to achieve a compact design. TCX
It is to provide O.

[Specific Means for Achieving the Object] The specific means taken by the present invention to achieve the above-mentioned object is to use a crystal oscillator with a crystal resonator whose resonant frequency changes depending on changes in temperature; a temperature sensor section that outputs a pulse whose period changes approximately linearly with respect to the temperature sensor; and a sequential memory section that has a plurality of groups of N consecutive addresses and stores temperature compensation data of the crystal oscillator. and,
The digitally controlled temperature-compensated crystal oscillator includes an operation control section that replaces the number of pulses M of the temperature sensor section in a predetermined period with an approximate multiple of N and supplies the same as an addressing signal to the sequential memory section.

[Summary of the invention]

The present invention uses a sequential memory section, that is, a ROM to which an address designation input signal is continuously input from one terminal, as the memory section that holds data related to temperature compensation, so that the peripheral wiring of the sequential memory section is simplified. TCXO, which enables extremely compact and highly accurate temperature compensation.
becomes.

〔Example〕

Hereinafter, the DTCXO of the present invention will be explained based on the drawings.

FIG. 1 is a block diagram showing the configuration of DTCXOl 0 of the present invention.

DTCXOl 0 includes a voltage controlled crystal oscillator 1, a temperature sensor section 2, a reference oscillator 3, a sequential memory section 4 that holds a plurality of data related to temperature compensation, and an operation control section 5 that controls addressing of the sequential memory section 4.
and a D/A converter 6 that converts the digital signal into analog.
It is composed of.

The crystal oscillator 1 includes a crystal resonator 7 as an oscillation source, an oscillation circuit, etc., and oscillates at a predetermined frequency. In addition, crystal oscillator 7
Since the resonant frequency fluctuates due to temperature changes, a circuit is provided in which the load capacitance of the crystal resonator 7 changes depending on the applied voltage, and the applied voltage is controlled so that the oscillation frequency remains constant even with temperature changes. It is carried out. A signal for this control is given from the D/A converter 5.

The temperature sensor section 2 is for detecting the ambient temperature in order to compensate for the temperature of the crystal oscillator 1, and as shown in FIG. 2, its cycle changes approximately linearly with respect to changes in the ambient temperature. The counter part 9 counts temperature pulses a from the oscillating part 8 and provides a temperature count signal to the operation control part 5.

The reference oscillator 3 is used to determine a reference time for dividing the temperature count signal outputted from the temperature sensor section 2 into predetermined periods, and similarly to the temperature sensor section 2 shown in FIG. It consists of a counter section and a counter section (both not shown). Incidentally, it is preferable that the oscillation pulse of the oscillation section does not change with respect to temperature. According to FIG. 1, the reference time reset signal C output from the reference oscillator 3 is input to the operation control section 5. The sequential memory section 5 includes a serial input ROM 31 and a shift register 32 as shown in FIG. It consists of The serial input ROM 31 has 1-bit data D for address A, and the address designation signal d is serially inputted to one input terminal 33 as the number of pulses generated by the operation control section 5. Data regarding the applied voltage value necessary for temperature compensation is used as one word, which is N digits arranged by digits Dx+1 to Dx+n connected to N consecutive addresses AX+1"AX+n (x is an arbitrary number). For example, 256 bits. N in ROM of 5
Then, 51 types of words can be obtained. Data D+= of addresses A1 to A5 without using address Ao
Ds is the first word, data D of addresses A6 to AIO, ~DI6 are the second word, . . . address A251
~A255 data D251 to D255 can be assigned as the 51st word. Now, when the address designation signal d is serially input from the input terminal 33 and the number of pulses M is 10, the second word from address A6 to AIO is output to the shift register 32. That is, the shift register 32 obtains temperature compensation data of "10010". That is, there are 2N types per word (N=5
Any temperature compensation data can be held in the sequential memory section 3 from among 32 types).

The operation control section 5 replaces the temperature count signal d outputted from the temperature sensor section 2 during the period determined by the reference oscillator 3 with an address signal d according to the data allocation of the sequential memory section 4. It is given to

As mentioned above, the sequential memory section 4 stores N consecutive (
In the example, since the data D at the address N-5) is used as one word (5bit) as a group, the operation control unit 5 outputs the temperature count signal from the temperature sensor 1 to the final address per word, for example. In Figure 3, 5, 10.
15...255 (address 0 is not used), which is the number M of pulses that is a multiple of N, and is output to the sequential memory section 4 as the address signal d.

For example, when performing temperature compensation in 1°C increments within the temperature range of 0'' to 51°C, the above temperature range is
(in case of tROM), and 5b in each area.
The temperature compensation data of it is written, and the number M of temperature count signals outputted from the temperature sensor section 2 is m in the above temperature range based on the reference time determined by the reference oscillator 3.
When the temperature changes linearly from M to m+256 (m is an arbitrary integer), the operation control unit 5
If so, output 10 pulse address designation signals d to the serial input terminal of the sequential memory section 4 and extract the second temperature compensation word at addresses A6 to AIO.Now, even if the temperature count number M is m+6. For example, an addressing signal d of 10 pulses rounded up to a multiple of N approximating "6" is output to the serial input terminal. That is,
When the temperature count number M is m+b, the number of pulses rounded up to a multiple of N that approximates b is outputted to the serial input terminal of the sequential memory section 4 as the address designation signal d. In addition to rounding up b of the temperature count number m+b, it may be rounded down or converged to a neighboring multiple of N.

If the number of pulses of the temperature count signal S from the temperature sensor section 2 increases or decreases linearly from 1 to about 256 within a predetermined temperature range, the temperature count signal S is used as is as the address designation signal d, and the temperature count signal S is When the number of pulses M is not a multiple of ``5'', the reset signal C from the reference oscillator 3 may be delayed by the operation control unit ``5'' to be a multiple of 5 and then output as the address designation signal d. .

The temperature compensation data e having Nb1t as one word output from the sequential memory section 4 in this manner is input to the D/A converter 6 and becomes a voltage value applied to the crystal oscillator 1.

In the embodiment, 256 bits of R is stored in the sequential memory section 4.
OM is used, but with the increased capacity of today's memory elements, it is easy to widen the temperature range for temperature compensation of the crystal oscillator, and by increasing the number of N bits per word. It is also easy to use multiple compensation degrees.

〔Effect of the invention〕

As described above, in the DTCXO1 of the present invention, that is, the digitally controlled temperature-compensated crystal oscillator, the temperature compensation data of the crystal oscillator is held in the sequential memory section, and the address of the memory section is serially specified using one input line. If the peripheral wiring of the sequential memory section is reduced and miniaturization is achieved, and the number of addresses corresponding to one word is N, then
Since one of the 2N species can be used as temperature compensation data,
The oscillation frequency of the crystal oscillator can be compensated with high precision.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the digitally controlled temperature compensated crystal oscillator of the present invention, FIG. 2 is a block diagram showing the configuration of the temperature sensor section in FIG. FIG. 2 is a block diagram showing the configuration of a sequential memory section in the figure. FIG. 4 is a block diagram showing the configuration of a conventional digitally controlled temperature compensated crystal oscillator. 2...Temperature sensor section 4...Sequential memory section 5...Operation control section

Claims (1)

[Scope of Claims] A crystal oscillator including a crystal oscillator whose resonant frequency changes with changes in temperature; a temperature sensor section that outputs pulses whose period changes approximately linearly with changes in temperature; a sequential memory section having a plurality of addresses as one group, and in which temperature compensation data of the crystal oscillator is stored; , and an operation control section that provides an address designation signal to the sequential memory section.