JPH02141026A - Method for reducing energy consumption of digital temperature compensating oscillator - Google Patents

Abstract

PURPOSE:To decrease the compensating operation of a period without the temperature change and to reduce the current consumption by controlling the next frequency counting interval time by the variation of a frequency counted result. CONSTITUTION:In a digital temperature compensating oscillator, each time temperature information is extracted for compensation, a temperature change situation, which is previous or from several times before, is stored into a controller 9 and compared with the present result stored in a register 6. When the temperature change does not occur, the compensating voltage is not updated, and the control is executed so as to lengthen an interval up to the next temperature compensating operation. In such a way, by controlling the compensating operation interval time in accordance with the temperature change situation, the energy consumption is reduced and the compensating accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a digital temperature compensated oscillator that compensates for fluctuations in oscillation frequency due to temperature changes based on digitally encoded temperature information, and in particular, This invention relates to a control method for a digital temperature compensation circuit that reduces current consumption as much as possible.

(Prior art) As a means to suppress fluctuations in the oscillation frequency due to temperature changes and always obtain a stable output, ambient temperature information is converted into a digital (G) signal, and this signal is used to generate a control voltage code that should be output in response to each temperature. There exists a digital temperature compensated oscillator configured to read from a memory device storing the v control voltage code and create a control voltage to supply to a voltage controlled oscillator based on the v control voltage code. It is attracting attention due to its adaptability to mass production.

FIG. 2 is a block diagram illustrating an example of the configuration of a conventional digital temperature compensated oscillator and an example of its control.

As a voltage controlled oscillator, one using a crystal oscillator (VCXO) is generally used, so
Although the description will focus on an example using a VCXO, the present invention need not be limited to this example.

In Fig. 2, reference numeral I indicates an oscillator as a temperature sensor whose oscillation frequency changes sensitively in response to temperature. The oscillation frequency changes at a rate of -).

The output of this sensor generator 4H is converted into a low-cycle pulse waveform by a frequency divider 2 to control a gate circuit of a frequency counter 3.

The frequency counter 3 also receives the output of the voltage controlled water quality oscillator (VCXO) 4 to be compensated by the second frequency division 23.
The number of pulses of the frequency-divided signal of the VCXO4 passing through the gate circuit Fj is counted.

In this case, since the output frequency of the temperature sensor oscillator l fluctuates due to changes in temperature, the number of signal pulses from the VCXO4 measured by the Ijt number counter 3 per cycle fluctuates depending on the temperature, and this pulse number represents the temperature at that point. Extracted as information.

Therefore, based on the result counted by the frequency counter 3, a digital signal of predetermined bits is generated in the next address register 6, and is inputted to the ROM 7 which stores the compensation voltage code to be output as an address signal.

r< OM When an address signal is manually input to 7, the digital signal stored in each address is output and this is D.
The voltage is converted into a DC voltage by the /A converter 8 and applied as a control voltage to the VCXO 4.

In this example, temperature information is obtained by counting the output frequency of the VCXO 4 using the output pulses of the sensor oscillator 1. The relationship between the gate control signal and the reference pulse when counting is as follows: 1. An inverse version of the fertilizer has also been put into practical use.9 Incidentally, in such a digital temperature compensated oscillator, temperature is measured at a certain predetermined period, that is, a frequency counting operation is performed, but in general, in digital signal processing, the clock frequency is A relatively large amount of current is required depending on the temperature compensation operation, and the required current is consumed each time the temperature compensation operation is performed.

When using such an oscillator in a small portable device, a major issue is how to reduce its current consumption in view of the balance between built-in battery capacity and usage time.

(Object of the Invention) The present invention has been made in view of the above, and provides a method for reducing the current consumption of a digital temperature compensated oscillator. The purpose of this invention is to provide a digital compensation oscillator that prevents an increase in current consumption due to frequency counting and suppresses power consumption to the minimum necessary.

(Summary of the Invention) In order to achieve the object 2, the present invention stores, in a digital temperature compensation oscillator, the temperature change status from the previous time or several times before each time temperature information is extracted for compensation. If there is no temperature change compared to this result, compensation type II-
is not updated and the interval until the next temperature compensation operation is extended.

Furthermore, if necessary, the compensation interval can be shortened if the temperature change is large.

Book 5 like this? ! IWJ is characterized by reducing power consumption and improving compensation accuracy by controlling the compensation operation interval time according to temperature change conditions.

(Embodiments) A method for reducing power consumption of a digital temperature compensated oscillator according to the present invention will now be described in detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention, and the same parts as in FIG. 2 are denoted by the same symbols and redundant explanations will be omitted.

In this figure, symbols 1 to 8 are the temperature sensor oscillator, the frequency divider 1 frequency counter, and the vcx
o, address register, ROM and D/A converter.

In this embodiment, in addition to the blocks 1 and 1, the controller 9
A third frequency divider IO is provided, and the temperature change condition is detected by this controller 9, and the repetition period or interval of frequency counting is controlled based on the result.

This controller 9 has a signal obtained by further dividing the signal pulse 1 of the first frequency divider 2 by the frequency divider IO! ], the digital signal 1) of the counting result from the frequency counter 3, and the output P4 of the address register 6, and a signal P6 created based on these signals is sent to the frequency counter 3, the address register 6, and the ROM 7. and the second frequency divider 5, respectively.

The operation in the above configuration will be explained.

The output of the temperature sensor oscillator l, which varies depending on the temperature, is converted into a pulse P1 having a pulse width of 0.0 Isec every O, l5ec by a frequency divider 2, and is inputted to a frequency counter 3. At the same time, this pulse P is converted into a 1.6 sec cycle pulse (2)ll by the third frequency divider 10 and is also supplied to the controller 9.

Frequency counter 3LmLtVCXO4 (7) 12.8M
The oscillation output of Hz is converted to 6.4MHz by the second frequency divider 5, and the frequency of this signal is counted using the pulse P+ from the Moeki frequency divider 2 as a gate pulse, and the counted value is stored in the address register. After being converted into an address signal in step 6, it is manually input to the ROM 7.

At this time, address register 6 is used until the next count is performed.
The latest address value is stored.

In the ROM 7, a compensation code is stored corresponding to each address value, and this compensation code is set to V in correspondence with each temperature.
It represents the control voltage to be applied to the CXO 4 and is converted into a DC voltage by the DΔ converter 8.

The DC voltage thus created is vcx.

4 as a frequency control voltage, and the signal of the VCXO4 obtained by this control is applied to necessary devices as an oscillation output.

The following control is performed every 0.1 sec of the output pulse [] of the first frequency divider 2, and each time the frequency counter 3. Address register 6, ROM 7 and D/
The A converter 8 operates, and this operation consumes a relatively large amount of current.

Therefore, in the present invention, the controller 9 is as follows! ,'' function to reduce current consumption.

The output P of the frequency divider 2 is further divided by the third frequency divider 10 and applied to the controller 9 as a 1.6 sec periodic pulse I).
The frequency count result for the c period is compared with the previous count result stored in the address register 6.

This comparison is performed in the controller 9 by comparing the input signals P, (joint measurement results) and P4 (results of the previous four measurements), and if they are different, it is assumed that there has been a temperature change.

The next frequency measurement is performed after 0.1 sec based on the pulse P1, and similarly compared with the measurement result of 1111 to detect the change.

While the temperature change is being detected in this manner, a compensation operation is performed every 0,15 ec, and a control voltage based on the sequentially updated address code is supplied to the VCXO4.

Next, if there is no temperature change, the previous measurement result and the joint result will be the same, so in this case, the contents of the address register 6 are not updated and the ROM 7 is not accessed.
Further, assuming that there is no rapid temperature change after that, the controller 9 immediately outputs a pulse P (disable signal) to the frequency counter 31 and the frequency divider 5. The operations of address register 6 and ROM 7 are stopped.

During this time, the compensation code by the I)/A converter 8 is fixed to the one immediately before the disable signal is output, so the control voltage to the VCXO 4 is fixed to the value at that time.

At the same time, when the controller 9 receives a 1.8 sec periodic pulse P8, it cancels the disable pulse P1 and starts counting again, and similarly compares the result obtained with this and the previous counting result and compares both. If there is a difference,
The address register is updated using the count value at this time as an address, and the next counting operation is performed using the P+ pulse as the O,
If the results of the zero-order measurement performed after 1 sec are the same, the controller 9 outputs the disable pulse P again.

In this way, if no temperature change is detected, period 1
．． If the counting operation is performed every 6 seconds, unnecessary counting operations can be omitted and current consumption can be significantly reduced.

In the above example, when there is no temperature change, the following compensation operation is performed in 1.
Although the ink-pal is fixed after 6 seconds, the present invention is not limited to this and various modifications are possible.

For example, if no temperature change has been detected as a result of the past several compensation operations performed at intervals of 1.6 seconds, power consumption can be further reduced by further lengthening the intervals.

To do this, the number of times no temperature change was observed is stored in memory, and when this exceeds a predetermined number of times, the interval until the next compensation operation is calculated by dividing the frequency of the signal P2 by 2 and dividing the signal P2 into a cycle of 3.2 seconds. A pulse r'2 is generated and the pulse is performed according to this quimming.

As an example of changing the history, if a large temperature change is observed when comparing the temperature measurement results of 1j11 and the current results, the interval until the next time is reversed and changed to O, Ise.
<: Can be made shorter.

According to this method, it is possible to follow rapid temperature changes and perform more accurate compensation.

In addition, each numerical value shown in Example 1 is an example, and is not limited to this, and the interval time is 0.1 s.
ec, 1.6sec, etc. can be changed to a: depending on the surrounding environment in which these oscillators are used, and vcxo
It can be widely applied not only to voltage controlled oscillators or similar devices.

Also, the memory in controller 9? Add one, store the count value of 1 for the previous time and 1 for the second time in each memory, compare the count value of these two previous times with the count value of this time, and when the champion wins, the next count value is stored. It may be configured to lengthen the interval until measurement, and shorten the interval until the next measurement if the previous two values and the current count value do not match. Or two more memories, 35!1
It is also possible to compare the measured value of 3 times m1.4 times mj with the current measurement.

() Effect of R1 light) As is clear from the above explanation, the present invention minimizes the compensation operation during the period where there is no temperature change in the digital temperature compensated oscillator, thereby significantly reducing the 7a current consumption. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a block diagram showing a conventional digital temperature compensated oscillator. Code 1...Temperature sensor oscillator, 2.5 and IO...
Frequency divider, 3...Frequency counter, 4...■cXO1
6...Address register, 7...110M, 8...
・■) Δ converter, 9...Controller patent applicant Toyo Tsushinki Co., Ltd. agent Patent attorney Hitoshi Suzuki Figure 2 Descriptive, =: f Yumasa f'! , 7F (7J Illusion: S Display of the case 1986 Patent Application No. 294240 Name of the invention Person who corrects method for reducing power consumption of digital temperature compensated oscillator / Relationship with the 1f case Patent applicant name Title Toyo Tsushinki Co., Ltd.

Claims (1)

[Claims] (1) A temperature sensor oscillator whose oscillation frequency changes depending on the temperature, a voltage controlled oscillator whose oscillation frequency is controlled by voltage, and a gate circuit controlled by the output of one of these two oscillators to control the output frequency of the other oscillator. In a frequency counting circuit that performs counting and a digital temperature compensation oscillator that generates a control voltage to be supplied to the voltage controlled oscillator based on the counting result, the next frequency counting is determined based on the amount of change between the previous frequency counting result and the current frequency counting result. A method for reducing power consumption of a digital temperature compensated oscillator characterized by controlling interval time.