JP2004023634A - High frequency oscillation circuit, temperature compensation method for high frequency oscillation circuit, and wireless communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency oscillation circuit that can be configured by employing a frequency synthesizer having a small change in the frequency due to a temperature variation at a low cost independently of a power supply voltage and to provide a temperature compensation method for the high frequency oscillation circuit and a wireless communication apparatus provided with the high frequency oscillation circuit. <P>SOLUTION: The high frequency oscillation circuit is provided with: a reference oscillation circuit for outputting a reference oscillation frequency signal; a storage device for storing in advance the temperature characteristic of a frequency signal outputted from the reference oscillation circuit; a temperature sensor for sensing surrounding temperatures; a control unit for outputting a correction value depending on the surrounding temperature sensed by the temperature sensor on the basis of the temperature characteristic stored in the storage device; and the PLL frequency synthesizer for outputting a high frequency output signal according to a setting value based on the frequency signal outputted from the reference oscillation circuit and the correction value outputted from the control unit. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for compensating the temperature of an output frequency in a high-frequency oscillation circuit used for a radio communication device such as a car phone, a mobile phone, and a radio paging device. The present invention relates to a high-frequency oscillation circuit which can be configured at low cost without depending on a power supply voltage, a temperature compensation method for the high-frequency oscillation circuit, and a wireless communication device including the high-frequency oscillation circuit.
[0002]
[Prior art]
A high-frequency oscillation circuit used for wireless communication is required to have a small change in oscillation frequency with temperature.
[0003]
Many high-frequency oscillator circuits use a PLL (Phase Locked Loop: a method of obtaining a constant frequency by feeding back the phase of an oscillation frequency) to oscillate a desired frequency. Since the accuracy of the oscillation frequency of the PLL frequency synthesizer is determined by the accuracy of the reference oscillation, a TCXO (Temperature Compensated Crystal Oscillator: crystal oscillator with a temperature compensation circuit) including a crystal oscillator and a temperature compensation circuit is used for the reference oscillation. Is often used.
[0004]
[Problems to be solved by the invention]
However, TCXO is generally expensive, and has a problem in that the range of power supply voltage for guaranteeing operation is small, and it is difficult to directly drive, for example, from a battery.
[0005]
The present invention provides a high-frequency oscillation circuit that can be configured using a frequency synthesizer in which a frequency change due to a temperature change is small at low cost and without depending on a power supply voltage, a temperature compensation method for the high-frequency oscillation circuit, and the high-frequency oscillation circuit. It is an object to provide a wireless communication device including an oscillation circuit.
[0006]
[Means for Solving the Problems]
The present invention employs the following configuration in order to solve the above problems.
First, an inexpensive reference oscillation circuit whose temperature characteristics are known in advance is used as the reference oscillation circuit instead of an expensive crystal oscillator such as TCXO. The minimum unit of the frequency that can be set by the PLL frequency synthesizer, that is, the resolution is set to a value sufficiently smaller than the required accuracy. For this purpose, the comparison frequency obtained by dividing the reference oscillation is set to a low value, or a N-divided PLL frequency synthesizer is used.
[0007]
Further, a temperature sensor and a table (storage device) for storing a correction value of the temperature characteristic are provided.
The deviation due to the ambient temperature can be corrected by detecting the ambient temperature with the temperature sensor and correcting the set value of the PLL frequency synthesizer.
[0008]
That is, according to one embodiment of the present invention, a high-frequency oscillation circuit of the present invention includes a reference oscillation circuit that outputs a frequency signal of reference oscillation, and a storage device that previously stores temperature characteristics of the frequency signal output by the reference oscillation circuit. A temperature sensor for detecting a peripheral temperature, a control device for outputting a correction value based on a temperature characteristic stored in the storage device from the ambient temperature detected by the temperature sensor, and the reference oscillation circuit. A PLL frequency synthesizer that outputs a high-frequency output signal based on a set value based on a frequency signal to be output and a correction value output by the control device is provided.
[0009]
This makes it possible to use an inexpensive frequency synthesizer in which a change in frequency due to a temperature change is small and to configure a high-frequency oscillation circuit independent of the power supply voltage.
[0010]
According to one embodiment of the present invention, a wireless communication device of the present invention includes the above-described high-frequency oscillation circuit.
According to one aspect of the present invention, a temperature compensation method according to the present invention is a temperature compensation method executed in a high-frequency oscillation circuit, wherein a temperature characteristic of a frequency signal output from a reference oscillation circuit is stored in advance, From the ambient temperature detected by the sensor, a correction value is output based on the previously stored temperature characteristic, and a set value based on the frequency signal output by the reference oscillation circuit and the correction value output by the control device Output a high-frequency output signal.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a functional configuration diagram of a high-frequency oscillation circuit to which the present invention is applied.
[0012]
1, the high-frequency oscillation circuit 10 includes a reference oscillation circuit 1, a storage device 2, a PLL frequency synthesizer 3, a control device 4, and a temperature sensor 5.
The reference oscillation circuit 1 generally uses a crystal oscillator, and outputs the reference oscillation to a PLL frequency synthesizer. This crystal oscillator has a temperature characteristic of an oscillation frequency according to an individual difference.
[0013]
FIG. 2 is a diagram showing the temperature characteristics of the oscillation frequency in a quartz oscillator that is a general reference oscillation circuit.
In FIG. 2, for example, the difference in the rate of change of frequency at a temperature of 0 ° C. is the largest, which is 20% or more, and the individual difference is large, and it cannot be said that it is an error range.
[0014]
Returning to the description of FIG. 1, the storage device 2 stores in advance a temperature characteristic according to the individual difference of the reference oscillation circuit 1 as shown in FIG.
The temperature sensor 5 is, for example, a thermistor or a semiconductor sensor, detects an ambient temperature, and outputs the detected temperature to the control device 4.
[0015]
The control device 4 samples the ambient temperature detected by the temperature sensor 5 and searches the storage device 2. Then, based on the temperature characteristics stored in the storage device 2, the setting data in which the deviation due to the temperature is corrected is output.
[0016]
The PLL frequency synthesizer 3 corrects the reference oscillation output from the reference oscillation circuit 1 based on the setting data output from the control device 4, obtains a temperature-compensated high frequency output signal, and outputs the signal.
[0017]
More specifically, the above-described high-frequency oscillation circuit can be applied to a wireless communication device such as a mobile phone, a mobile phone, and a wireless paging device.
FIG. 3 is a flowchart showing the flow of the temperature compensation processing in the high-frequency oscillation circuit to which the present invention is applied.
[0018]
First, in step S31, the storage device stores in advance a temperature characteristic corresponding to an individual difference of the reference oscillation circuit in a table format.
In step S32, the control device samples the ambient temperature detected and output by the temperature sensor.
[0019]
Then, in step S33, the control device searches the temperature characteristics stored in the storage device in advance in step S31 based on the ambient temperature sampled in step S32, and outputs setting data in which a deviation due to temperature is corrected.
[0020]
In step S34, the PLL frequency synthesizer corrects the reference oscillation output from the reference oscillation circuit based on the setting data output by the control device in step S33.
[0021]
In step S35, the PLL frequency synthesizer outputs a high-frequency output signal with temperature compensation based on the data corrected in step S34.
In order to suppress the frequency fluctuation of the high-frequency output signal due to the ambient temperature to a desired value or less, it is necessary to sufficiently reduce the frequency resolution that can be set by the PLL frequency synthesizer. In the case of a normal PLL frequency synthesizer, this is determined by the comparison frequency obtained by dividing the reference oscillation, so that it is necessary to lower this. However, if the comparison frequency is reduced, the time required for the PLL frequency synthesizer to lock to the desired frequency becomes longer. In such a case, the comparison frequency is increased by applying a PLL frequency synthesizer of N frequency division. By lowering only the resolution while keeping the state, high-speed locking can be achieved as a result.
[0022]
Note that each component of the high-frequency oscillation circuit described with reference to FIG. 1 can be made hard to be affected by the power supply voltage.
As described above, the embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the above-described embodiments, and does not depart from the gist of the present invention. Various configurations or shapes can be taken within.
[0023]
【The invention's effect】
As described above, according to the present invention, a high-frequency oscillation circuit that can be configured using a frequency synthesizer with a small change in frequency due to temperature change at low cost and without depending on the power supply voltage, A wireless communication device having a high-frequency oscillation circuit can be obtained.
[0024]
Further, according to the present invention, it is possible to realize a temperature compensation method for a high-frequency oscillation circuit that can use a low-cost frequency synthesizer and can generate a high-temperature signal with temperature compensation without depending on the power supply voltage. .
[Brief description of the drawings]
FIG. 1 is a functional configuration diagram of a high-frequency oscillation circuit to which the present invention is applied.
FIG. 2 is a diagram showing a temperature characteristic of an oscillation frequency in a quartz oscillator which is a general reference oscillation circuit.
FIG. 3 is a flowchart showing a flow of a temperature compensation process in the high-frequency oscillation circuit to which the present invention is applied.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 reference oscillation circuit 2 storage device 3 PLL frequency synthesizer 4 control device 5 temperature sensor 10 high-frequency oscillation circuit

Claims (3)

In high frequency oscillation circuits,
A reference oscillation circuit that outputs a reference oscillation frequency signal;
A storage device that stores in advance the temperature characteristics of the frequency signal output by the reference oscillation circuit,
A temperature sensor for detecting ambient temperature,
A controller that outputs a correction value based on the temperature characteristics stored in the storage device from the ambient temperature detected by the temperature sensor;
A PLL frequency synthesizer that outputs a high-frequency output signal by a set value based on a frequency signal output by the reference oscillation circuit and a correction value output by the control device;
A high-frequency oscillation circuit comprising: A temperature compensation method performed in a high-frequency oscillation circuit,
The temperature characteristic of the frequency signal output by the reference oscillation circuit is stored in advance,
From the ambient temperature detected by the temperature sensor, based on the previously stored temperature characteristics, output a correction value,
A temperature compensation method for a high-frequency oscillation circuit, comprising: outputting a high-frequency output signal based on a set value based on a frequency signal output by the reference oscillation circuit and a correction value output by the control device. A wireless communication device having the high-frequency oscillation circuit according to claim 1.

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