JP4403669B2 - Fractional N frequency synthesizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to temperature compensation of a fractional N system frequency synthesizer used in a communication device or the like.
[0002]
[Prior art]
As a conventional fractional-N frequency synthesizer, for example, as shown in FIG. 4, a reference frequency oscillating unit 2 that generates a reference frequency Fref based on a crystal resonator 21, and frequency temperature characteristic data 1c of the crystal resonator 21 Is stored in advance, temperature detecting means 5 for detecting temperature, accumulator 7 for outputting an overflow signal when the hold value exceeds a predetermined value, data from the storing means 4 and data from the temperature detecting means 5 The main frequency dividing number N and the step number K of the accumulator 7 based on the above, a main frequency divider 8 for dividing the frequency by the main frequency dividing number N from the control means 6, and the main frequency dividing A phase comparator 10 that compares the phases of the frequency-divided output Fcomp from the comparator 8 and the reference frequency Fref, a control voltage generator 3 that converts the output from the phase comparator 10 into a voltage, A voltage-controlled oscillator 9 that outputs an oscillation frequency Fvco from an output from the generation unit 3 and feeds back a part of the oscillation frequency Fvco to the main frequency divider 8 and spurious canceling means (not shown) for suppressing spurious are provided. It is a configuration.
[0003]
Here, the reference frequency oscillating unit 2 includes a crystal resonator 21, a crystal oscillation circuit 22, and a reference frequency divider 23, and a frequency Fx′tal oscillated by the crystal resonator 21 and the crystal oscillation circuit 22 is used as a reference. The reference frequency Fref divided by the frequency dividing number A is output.
[0004]
The main frequency divider 8 feeds back a part of the oscillation frequency Fvco, and switches between the main frequency division number N and the main frequency division number N + 1 given from the control means 6 by the overflow signal from the accumulator 7 having a predetermined holding value. Frequency division is performed and a frequency division output Fcomp is output to the phase comparator 10.
[0005]
The phase comparator 10 compares the phase of the frequency division output Fcomp obtained by dividing a part of the oscillation frequency Fvco of the voltage controlled oscillator 9 by the main frequency division number N given from the control means 6 with the phase of the reference frequency Fref.
[0006]
The control voltage generator 3 includes a charge pump circuit 31 that sucks and discharges current by an output pulse of the phase comparator 10, and a loop filter 32 that smoothes the current from the charge pump circuit 31 and converts the voltage. The oscillation frequency Fvco is output to the voltage controlled oscillator 9.
[0007]
In such a fractional N system frequency synthesizer, the storage means 4 stores the frequency temperature characteristic data 1c of the crystal resonator 21 in advance, and the temperature detection means 5 is a system incorporating a fractional N system frequency synthesizer. It is installed in the vicinity of (not shown), detects the temperature, and the control means 6 reads out the data with respect to the temperature detected by the temperature detection means 5 from the frequency temperature characteristic data of the storage means 4, and generates a frequency deviation. Temperature compensation is realized by correcting the main frequency division number N and the step number K of the accumulator 7 in the direction of cancellation.
[0008]
For example, an example of a temperature compensation method is shown below. FIG. 5 is an explanatory diagram showing the frequency temperature characteristic data 1c of the crystal unit 21 stored in advance in the storage means. The frequency-temperature characteristic data 1c of the crystal unit 21 uses an AT cut having a positive cubic curve depending on the cut angle of the crystal piece.
[0009]
Here, the temperature range required for a system (not shown) incorporating a fractional-N frequency synthesizer is data from P (° C.) to W (° C.), and ± G (ppm) is required for the system. It is a frequency deviation, and the temperature range in which the frequency deviation can be guaranteed is P (° C.) to Q (° C.) (where P <Q <W). At temperature S (° C.) (Q <S <W), the control means 6 sets the main frequency division number N and step number K calculated from the initial deviation correction value of the crystal resonator 21 and the frequency data to be oscillated. On the other hand, correction corresponding to −B (ppm) (B <G is satisfied) is performed, the main frequency division number N and the step number K are corrected, and given to the accumulator 7. As a result, the fractional N frequency synthesizer has an oscillation frequency Fvco that is lower by −B (ppm) than the oscillation frequency (Fvco + B (ppm)) at the temperature S (° C.) when temperature compensation is not performed, that is, the desired oscillation. It becomes possible to oscillate at a frequency, and temperature compensation can be performed without changing the oscillation condition of the crystal resonator 21.
[0010]
[Problems to be solved by the invention]
However, in the fractional-N frequency synthesizer as described above, the frequency temperature characteristic data of the crystal resonator stored in advance in the storage means is the frequency temperature characteristic data over the entire temperature range. In realization, there has been a problem that the control of a system incorporating the fractional-N frequency synthesizer becomes complicated.
[0011]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a fractional-N frequency synthesizer that can easily perform temperature compensation.
[0012]
[Means for Solving the Problems]
The fractional N-system frequency synthesizer according to claim 1 is a reference frequency oscillation unit that generates a reference frequency based on a crystal resonator, frequency temperature characteristic data of the crystal resonator, and a lighting / light-off operation in a lighting device, and Storage means for preliminarily storing temperature characteristic data in the lighting apparatus according to the elapsed time of operation, an accumulator for outputting an overflow signal when the hold value exceeds a predetermined value, frequency temperature characteristic data from the storage means, and in the lighting apparatus Control means for calculating a main frequency division number and the number of steps of the accumulator based on temperature characteristic data , a main frequency divider for frequency dividing by the main frequency division number from the control means, and the main frequency divider A phase comparator that compares the phase of the frequency-divided output from the reference frequency with the reference frequency, a control voltage generator that converts the output from the phase comparator, and Outputting an oscillation frequency from the output from the control voltage generation unit, it comprises a voltage-controlled oscillator is fed back a portion of the oscillation frequency to the main divider, and suppresses the spurious cancel means spurious, the storage means From the frequency temperature characteristic data from and the temperature characteristic data in the lighting equipment, the control means gives the frequency divider to the main frequency divider and the accumulator in a direction to cancel the generated frequency deviation with respect to the frequency temperature characteristic data. It is a fractional-N frequency synthesizer for use in a built- in lighting device that corrects the main frequency division number and the number of steps.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, reference embodiments and embodiments of the present invention will be described with reference to the drawings. Since the basic configuration of the fractional-N frequency synthesizer is the same as the structure shown in the prior art, the same portions are denoted by the same reference numerals, and description of common portions is omitted.
[0017]
First, a first reference embodiment of the present invention will be described with reference to FIG. Figure 1 is an explanatory diagram showing a fractional N system frequency-temperature characteristic data of the frequency synthesizer according to a first referential embodiment of the present invention.
[0018]
As shown in FIG. 1, crystal frequency temperature characteristic data 1a of the vibrator 21, a fractional-N mode a temperature range needed for a system incorporating a frequency synthesizer (not shown), in the first reference embodiment, P (° C.) ~ W (° C) data, and such data is stored in the storage means in advance. In addition, although the AT cut is used as the cut angle of the crystal piece of the crystal unit 21, the frequency temperature characteristic data of the crystal unit 21 may be a DT cut having a positive quadratic curve.
[0019]
The temperature detection means 5 uses a thermistor (not shown), and the main frequency divider 8 and the main frequency divider 8 in a direction to cancel out the generated frequency deviation based on the resistance value variation of the thermistor and the frequency temperature characteristic data 1a of the crystal resonator 21. By correcting the main frequency division number N and the step number K given to the accumulator 7 by the control means 6, temperature compensation can be performed without separately providing variable capacitance means (not shown).
[0020]
Note that the temperature compensation method is the same as that of the prior art, and thus the description thereof is omitted.
[0021]
In such a fractional N system frequency synthesizer, the temperature temperature characteristic data 1a of the crystal resonator 21 stored in advance in the storage means 4 is converted into a temperature range P (° C.) to W (° C.) required for a system incorporating the fractional N system frequency synthesizer. ), The storage capacity of the storage means 4 can be reduced, so that the control necessary for temperature compensation is simplified.
[0022]
Here, in the first reference embodiment, the temperature range required for a system incorporating a fractional N frequency synthesizer, data of P (° C.) to W (° C.) is stored in the storage means 4 in advance. When temperature compensation is performed only when the temperature data from the means 5 is equal to or higher than the upper limit temperature of the temperature range in which the frequency deviation can be guaranteed, that is, Q (° C.) or more, a part of the temperature range required for the system, for example, Only the data of Q (° C.) to W (° C.) is stored in advance in the storage means.
[0023]
In such a fractional N system frequency synthesizer, the temperature temperature characteristic data 1a of the crystal resonator 21 stored in advance in the storage means 4 is converted into a temperature range P (° C.) to W (° C.) required for a system incorporating the fractional N system frequency synthesizer. ), The storage capacity of the storage means 4 can be further reduced by storing only the temperatures Q (° C.) to W (° C.) that deviate from the frequency deviation, thereby simplifying the control necessary for temperature compensation. .
[0024]
Here, the temperature range that deviates from the frequency deviation is not limited to the range from the upper limit of the temperature at which the frequency deviation can be guaranteed, and any temperature range that deviates from the frequency deviation may be used. Good.
[0025]
In the first reference embodiment, the accumulator 7 is used. In this part, a configuration that realizes the same operation as the accumulator 7, such as an integrator, a Δ modulator, a differentiator, and a low-pass filter is provided. A Δ-Σ modulator (not shown) that suppresses the fractional spurious by moving the phase error output to the phase comparator 10 to the high frequency region outside the loop filter pass band may be used. In this case, since the integrator of the Δ-Σ modulator realizes an operation equivalent to that of the accumulator 7, the same effect as that obtained when the accumulator 7 is used can be obtained.
[0026]
Next, a second reference embodiment of the present invention will be described with reference to FIG. FIG. 2 is an explanatory diagram showing frequency temperature characteristic data of the fractional N-type frequency synthesizer according to the second reference embodiment of the present invention, and a description of common parts with the first reference embodiment is omitted.
[0027]
In general, the frequency temperature characteristic data of the crystal unit 21 can be defined by a variation range at a certain temperature. Therefore, as shown in FIG. 2, the frequency temperature characteristic data 1b of the crystal resonator 21 is data including a variation range existing in a region between the upper limit curve L1 and the lower limit curve L2 of the variation as described later. Is previously stored in the storage means. Here, similarly to the first reference embodiment, the temperature range that can guarantee the frequency deviation ± G (ppm) when not to apply temperature compensation is P (℃) ~Q (℃) .
[0028]
The temperature at which the variation upper limit value curve L1 becomes G (ppm) is Q (° C.), and the temperature at which the variation lower limit value curve L2 becomes −G (ppm) is P (° C.). Further, the temperature at which the upper limit curve L1 of variation is −G (ppm) is U (° C.), and the temperature at which the lower limit curve L2 of variation is G (ppm) is V (° C.). , U <P <Q <V). The average value of the upper limit value curve L1 and the lower limit value curve L2 of the variation is referred to as an average value curve LA.
[0029]
Thus, by using the upper limit value curve L1, the lower limit value curve L2, and the average value curve LA of the variation, the temperature range in which the frequency deviation ± G (ppm) can be guaranteed is from P (° C.) to Q (° C.), U It can be expanded from (° C.) to V (° C.).
[0030]
In such a fractional-N frequency synthesizer, it is possible to expand the temperature range in which the frequency deviation can be guaranteed by performing temperature compensation using data including a variation range between the upper limit curve L1 and the lower limit curve L2. It becomes possible. Further, by storing the frequency temperature characteristic data 1b including the variation range in the storage unit 4 in advance, it is not necessary to change and write the frequency temperature characteristic data 1b for each crystal resonator having a different lot or the like. The control required for this becomes simple.
[0031]
Here, in the second reference embodiment, the temperature range required for the system incorporating the fractional N system frequency synthesizer is, for example, P (° C.) to V (° C.), and the temperature data from the temperature detecting means 5 is When temperature compensation is performed only when the temperature is equal to or higher than the upper limit temperature of the temperature range in which the frequency deviation can be guaranteed, Q (° C.), a part of the temperature range required for the system, for example, Q (° C.) to V (° C.) By storing the data in the storage unit 4 in advance, the storage capacity of the storage unit can be further reduced.
[0032]
In the first reference form and the second reference form, the thermistor is used as the temperature detecting means 5, but a band gap formed by a PN junction is used as the temperature detecting means, and the potential difference output from the band gap and the frequency of the crystal resonator 21 are used. The temperature compensation may be performed by correcting the main frequency division number N and the step number K applied to the main frequency divider 8 and the accumulator 7 in the direction to cancel the generated frequency deviation by the control means 6 based on the temperature characteristic data. Since the fractional N frequency synthesizer may be integrated into an IC, the temperature detection means 5 using the band gap can be configured in the same IC, and additional components are added to the fractional N frequency synthesizer. There is no need to do so, and miniaturization becomes possible.
[0033]
Next, an embodiment according to the present invention will be described . Full fractional N system frequency synthesizer, in a system such as that incorporated in the lighting device of the white heat lamp device or the like, in advance by measuring the temperature characteristics of the apparatus by turning on and off operation and the elapsed time of said operating in the lighting equipment, storage By storing in the means 4, the temperature detecting means 5 can be used instead. In addition, description of a common part with 1st reference form is abbreviate | omitted.
[0034]
An embodiment according to the present invention will be described with reference to FIG. FIG. 3 is an explanatory diagram showing the lighting state and elapsed time of a lighting device connected to a communication device equipped with the fractional N system frequency synthesizer of the present invention .
[0035]
The temperature of the lighting device (not shown) such as an incandescent lamp device is determined by the lighting control means (not shown) for lighting control and the lighting state (lighting / extinguishing operation) of the lighting device as shown in FIG. It is possible to easily grasp the relationship with the elapsed time.
[0036]
As shown in FIG. 3, when temperature compensation is not performed, the lighting device starts lighting when the temperature inside the device is equivalent to the outside air temperature (point a1), the temperature inside the device starts to rise, and the temperature range allowable value limit The temperature inside the device continues to rise and reaches D ° C (point a3), and the temperature rise reaches a stable region at point a3. When the lighting ends at point a4, the temperature inside the device gradually decreases with heat dissipation, falls below C ° C. which is the temperature range allowable value limit at point a5, and decreases to the equivalent of outside temperature at point a6. Here, the vertical axis represents the temperature in the device, and the horizontal axis represents the elapsed time of the operation.
[0037]
Therefore, the temperature characteristics in the device due to such lighting / extinguishing operation and the elapsed time of the operation are measured in advance and stored in the storage unit 4, so that the temperature detection unit 5 can be substituted.
[0038]
In the control means 6, the frequency of the crystal resonator 21 stored in advance in the storage means 4 with respect to the main frequency division number N and the step number K calculated from the initial deviation correction value of the crystal resonator 21 and the frequency data to be oscillated. The temperature characteristic data (not shown) and the operation of the lighting control means are detected, and the in-apparatus obtained from the relationship between the lighting state (lighting / extinguishing operation) stored in the storage means 4 and the elapsed time of the operation is obtained. The main frequency division number N and the step number K are corrected according to the temperature.
[0039]
Specifically, within the operating temperature range of the system, up to C ° C., the standard value of the frequency deviation cannot be deviated without temperature compensation, but when the temperature is in the vicinity of point a2, the crystal resonator 21 Temperature compensation is started by frequency temperature characteristic data. Note that similar temperature compensation is performed at points a3, a4, and a5. When the time elapsed after turning off the light passes the point a5, the temperature deviation falls within the standard value of the frequency deviation without temperature compensation.
[0040]
In such a fractional-N frequency synthesizer, the temperature compensation is performed by the temperature characteristic data around the equipment stored in advance in the storage means 4, so that the hardware for realizing the temperature detection means 5 is not required, and the system is realized at a simple and low price. it can.
[0041]
Here, in the embodiment according to the present invention, the case where the fractional-N frequency synthesizer is incorporated in the lighting device has been described. However, the temperature change is large as in an engine room of an automobile, for example, and the operation is performed as shown in FIG. The state and the elapsed time of the operation may be incorporated in a relatively stable device.
[0042]
In addition, as another embodiment, a separate timekeeping function capable of acquiring date and time information is added to the temperature detection means 5, and statistical temperature data at the device usage location, for example, hourly, daily, monthly, etc. Statistical temperature data is stored in the storage means 4 in advance, the date and time information obtained by the temperature detection means 5 to which the time measuring function is added, and the above-described statistical temperature data stored in the storage means 4 Temperature compensation may be performed by obtaining the information and correcting the main frequency division number N and the step number K given to the main frequency divider 8 and the accumulator 7 in the direction to cancel the generated frequency deviation by the control means 6. In such a case, since the temperature detecting means 5 can also function as a timekeeping function, there is no need to add a separate mounting component for temperature compensation.
[0043]
【The invention's effect】
As described above, in the fractional N system frequency synthesizer according to the first aspect of the present invention, the reference frequency oscillating unit that generates the reference frequency based on the crystal resonator, and the frequency temperature characteristics of the crystal resonator. Storage means for preliminarily storing data and temperature characteristic data in the lighting equipment based on the lighting / light-out operation of the lighting equipment and the elapsed time of the operation, an accumulator for outputting an overflow signal when the hold value exceeds a predetermined value, and the storage means Control means for calculating the main frequency division number and the number of steps of the accumulator based on the frequency temperature characteristic data from and the temperature characteristic data in the lighting device, and frequency dividing by the main frequency division number from the control means A main frequency divider, a phase comparator for comparing the phase of the frequency-divided output from the main frequency divider and the reference frequency, and an output from the phase comparator A control voltage generator for converting voltage, a voltage controlled oscillator for outputting an oscillation frequency from an output from the control voltage generator, and feeding back a part of the oscillation frequency to the main frequency divider, and a spurious cancel for suppressing spurious The frequency temperature characteristic data from the storage means and the temperature characteristic data in the lighting device, the control means causes the frequency temperature characteristic data to cancel out the generated frequency deviation with respect to the frequency temperature characteristic data. Since it is a fractional-N frequency synthesizer for use in a built- in lighting device that corrects the main frequency divider and the number of steps given to the main frequency divider and the accumulator, it is a device based on the turn-on / off operation and the elapsed time of the operation. The temperature characteristics are stored in the memory means in advance, so that temperature compensation can be stored without providing a temperature detection means. To perform the temperature characteristic data of the peripheral device stored in advance in the stage, the hard becomes unnecessary to achieve a temperature detecting means, the system can be realized with simple and low cost. Here, when measuring the temperature characteristics in the device according to the turn-on / off operation and the elapsed time of the operation in advance, if only a few change points from a1 to 6 as shown in FIG. 3 are recorded, A fractional-N frequency synthesizer that can contribute to reducing the storage capacity of the storage means without increasing the storage amount so much and can easily perform temperature compensation can be provided. In addition, although time measuring means for measuring which state of several changing points from a1 to 6 as shown in FIG. 3 is required is necessary, as this time measuring means, a reference frequency oscillation unit and a control means are used. It merely performs a timer counting action that has been widely performed in the past, and is only easily realizable.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a frequency-temperature characteristic data of the fractional-N type frequency synthesizer according to a first referential embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a frequency-temperature characteristic data of the fractional-N type frequency synthesizer according to a second referential embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a lighting state and an elapsed time of a lighting device according to a form connected to a communication device equipped with a fractional N system frequency synthesizer of the present invention .
FIG. 4 is a block diagram of a fractional-N frequency synthesizer according to a conventional example.
FIG. 5 is an explanatory diagram showing frequency temperature characteristic data of a fractional-N frequency synthesizer according to a conventional example.
[Explanation of symbols]
1a, 1b, 1c Frequency temperature characteristic data 2 Reference frequency oscillating unit 3 Control voltage generating unit 4 Storage unit 5 Temperature detecting unit 6 Control unit 7 Accumulator 8 Main frequency divider 9 Voltage controlled oscillator 10 Phase comparator 21 Crystal resonator 22 Crystal Oscillator 23 Reference frequency divider 31 Charge pump circuit 32 Loop filter L1 Upper limit curve L2 Lower limit curve LA Average curve

Claims (1)

A reference frequency oscillation unit that generates a reference frequency based on a crystal resonator, frequency temperature characteristic data of the crystal resonator, and temperature characteristic data in the lighting device based on the lighting / light-off operation of the lighting device and the elapsed time of the operation. Based on pre-stored storage means , an accumulator that outputs an overflow signal when the hold value exceeds a predetermined value, frequency temperature characteristic data from the storage means, and temperature characteristic data in the lighting device, Control means for calculating the number of steps of the accumulator, a main frequency divider that divides the frequency by the main frequency division number from the control means, and the phase of the frequency division output from the main frequency divider and the reference frequency A phase comparator to be compared, a control voltage generator for converting the output from the phase comparator, an oscillation frequency is output from the output from the control voltage generator, and the oscillation frequency A voltage controlled oscillator is fed back some number to the main divider, made and a suppressing spurious cancel means spurious, the temperature characteristic data of the frequency-temperature characteristic data as well as the lighting equipment from the storage means, by the control means, the relative frequency-temperature characteristic data, of the direction of canceling the generated frequency deviation the main divider and lighting equipment built for correcting the number of steps and the main frequency division number to be supplied to the accumulator Fractional N frequency synthesizer.

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