WO2016206384A1 - 晶体振荡器电路、晶体振荡器电路的调谐方法及存储介质 - Google Patents

晶体振荡器电路、晶体振荡器电路的调谐方法及存储介质 Download PDF

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WO2016206384A1
WO2016206384A1 PCT/CN2016/073540 CN2016073540W WO2016206384A1 WO 2016206384 A1 WO2016206384 A1 WO 2016206384A1 CN 2016073540 W CN2016073540 W CN 2016073540W WO 2016206384 A1 WO2016206384 A1 WO 2016206384A1
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control word
temperature
crystal oscillator
oscillator circuit
compensation
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PCT/CN2016/073540
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English (en)
French (fr)
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李超
谢豪律
张鹏北
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深圳市中兴微电子技术有限公司
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Publication of WO2016206384A1 publication Critical patent/WO2016206384A1/zh

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L1/00—Stabilisation of generator output against variations of physical values, e.g. power supply

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  • the present invention relates to the field of crystal oscillator technology, and in particular, to a crystal oscillator circuit, a tuning method of a crystal oscillator circuit, and a storage medium.
  • the Digitally Compensated Crystal Oscillator (DCXO) circuit is widely used in modern wireless communication chip systems. It is usually composed of the following parts: an oscillating amplifier that provides the negative resistance required for oscillation, ensuring the amplitude detection and control of the oscillating Circuits, some designs also add temperature compensation circuit to correct the drift of the oscillation frequency caused by temperature changes.
  • the method for realizing the tuning of the crystal oscillator circuit is mostly realized, the circuit is large and complicated, the frequency accuracy is not high, and the implementation cost is high; therefore, a crystal oscillator circuit and a tuning scheme thereof are provided, and the crystal oscillator circuit can be improved.
  • the frequency accuracy, high reliability and low cost have become an urgent problem to be solved.
  • embodiments of the present invention are directed to provide a crystal oscillator circuit, a tuning method of a crystal oscillator circuit, and a storage medium, which can improve the frequency accuracy of the crystal oscillator circuit, enhance user experience, and have high reliability and low cost. .
  • Embodiments of the present invention provide a method for tuning a crystal oscillator circuit, the method comprising:
  • the current digital voltage signal is converted by the input analog voltage signal and is related to temperature.
  • the method before the acquiring the first control word according to the current digital voltage signal and the temperature compensation table, the method further includes:
  • the temperature coefficient of the crystal is determined, and a temperature compensation table corresponding to the crystal is obtained according to the determined temperature coefficient.
  • the acquiring the first control word according to the current digital voltage signal and the temperature compensation table includes:
  • the acquiring the second control word according to the current AFC control word and the nonlinear compensation table includes:
  • the second compensation capacitor corresponding to the AFC control word in the nonlinear compensation table is obtained by using a lookup table according to the current AFC control word, and the second control word is generated according to the second compensation capacitor.
  • the capacitor array is adjusted according to the first control word and the second control word to implement tuning of the frequency of the crystal oscillator circuit, including:
  • the first control word and the second control word are added to obtain a third control word, and the size of the capacitor array is adjusted according to the third control word to implement tuning of the frequency of the crystal oscillator circuit.
  • the embodiment of the invention further provides a crystal oscillator circuit, the crystal oscillator circuit comprising: a temperature compensation circuit, a nonlinear compensation circuit and a tuning circuit; wherein
  • the temperature compensation circuit is configured to acquire a first control word according to a current digital voltage signal and a temperature compensation table
  • the nonlinear compensation circuit is configured to be based on a current AFC control word and a nonlinear compensation table Obtaining a second control word;
  • the tuning circuit is configured to adjust the capacitor array according to the first control word and the second control word to implement tuning of the frequency of the crystal oscillator circuit.
  • the current digital voltage signal is converted by the input analog voltage signal and is related to temperature
  • the crystal oscillator circuit further includes an analog to digital converter configured to convert the input analog voltage signal to a corresponding digital voltage signal.
  • the crystal oscillator circuit further includes a processor configured to determine a temperature coefficient of the crystal, and obtain a temperature compensation table corresponding to the crystal according to the determined temperature coefficient.
  • the temperature compensation circuit is configured to determine a corresponding temperature value according to the current digital voltage signal, and obtain a first compensation capacitor corresponding to the temperature value in the temperature compensation table by using a lookup table according to the temperature value. And generating a first control word according to the first compensation capacitor.
  • the nonlinear compensation circuit is configured to acquire a second compensation capacitor corresponding to the AFC control word in the nonlinear compensation table according to the current AFC control word by using a lookup table, and generate the second compensation capacitor according to the second compensation capacitor. Second control word.
  • the tuning circuit is configured to add the first control word and the second control word to obtain a third control word, and adjust a size of the capacitor array according to the third control word to implement tuning of the crystal.
  • the frequency of the oscillator circuit is configured to add the first control word and the second control word to obtain a third control word, and adjust a size of the capacitor array according to the third control word to implement tuning of the crystal.
  • the embodiment of the present invention further provides a computer storage medium storing a computer program configured to perform the tuning method of the crystal oscillator circuit of the embodiment of the present invention.
  • the crystal oscillator circuit, the tuning method of the crystal oscillator circuit and the storage medium provided by the embodiment of the invention acquire the first control word according to the current digital voltage signal and the temperature compensation table; according to the current AFC control word and the nonlinear compensation table Obtaining a second control word; adjusting the capacitor array according to the first control word and the second control word to implement tuning of the crystal oscillator circuit frequency.
  • the frequency accuracy and temperature characteristics of the crystal oscillator circuit can be improved, the user experience is enhanced, and the reliability is high. low cost.
  • FIG. 1 is a schematic flow chart of a tuning method of a crystal oscillator circuit according to an embodiment of the present invention
  • FIG. 2 is a schematic flow chart of a tuning method of a crystal oscillator circuit according to a second embodiment of the present invention
  • FIG. 3 is a schematic structural diagram of a circuit of a crystal oscillator circuit according to an embodiment of the present invention.
  • the first control word is obtained according to the current digital voltage signal and the temperature compensation table; the second control word is obtained according to the current AFC control word and the nonlinear compensation table; according to the first control word and the second The control word adjusts the array of capacitors to achieve tuning of the frequency of the crystal oscillator circuit.
  • a tuning method of a crystal oscillator circuit according to an embodiment of the present invention includes:
  • Step 101 Acquire a first control word according to a current digital voltage signal and a temperature compensation table.
  • This step can be implemented by a temperature compensation circuit in the crystal oscillator circuit
  • the step includes: determining a corresponding temperature value according to the current digital voltage signal, and acquiring a first compensation capacitor corresponding to the temperature value in the temperature compensation table according to the temperature value by using a lookup table, according to the first compensation capacitor Generating a first control word; the first control word is used to represent a size of a compensation capacitor required for a current digital voltage signal; and the first compensation capacitance corresponding to the temperature value is a minimum unit corresponding to the temperature value
  • the number of capacitors, that is, the first compensation capacitor is represented by the minimum number of unit capacitors.
  • the current digital voltage signal is input by an analog voltage signal input by a temperature sensing circuit Converted by an analog-to-digital converter and input to the temperature compensation circuit; the analog voltage signal is generated by the temperature sensing circuit and varies with temperature, that is, the analog voltage signal is temperature dependent, that is, The digital voltage signal is related to temperature, and the specific relationship is determined according to a currently used temperature sensor. For example, when the current temperature sensor is implemented by a thermistor, the digital voltage signal has a linear relationship with temperature;
  • Determining the corresponding temperature value according to the current digital voltage signal comprises: determining a corresponding temperature value according to a current digital voltage signal and a correspondence between the digital voltage signal and the temperature value.
  • the method before the acquiring the first control word according to the current digital voltage signal and the temperature compensation table, the method further includes:
  • the operation may be completed in an automated test before leaving the terminal of the crystal oscillator circuit, specifically in the frequency of the automated test Completed during the adjustment process;
  • the temperature coefficient of the crystal comprises: a first temperature coefficient a 1 , a second temperature coefficient a 2 and a third temperature coefficient a 3 ;
  • T 0 is the inflection temperature of the crystal, about 25°; the crystal may be AT cut;
  • ⁇ f c (T) represents the amount of frequency change when the temperature is T.
  • the determining the temperature coefficient of the crystal comprises:
  • the input resistance of the amplifier needs to match the series resonant impedance of the crystal.
  • the impedance of the amplifier and the impedance of the crystal may be mismatched during series resonance.
  • the crystal is usually operated in the parallel resonance mode. Due to the influence of the parallel capacitor C 0 , the frequency response is worse than the series resonance. Therefore, a capacitor is usually connected in parallel across the crystal to reduce the C 0 to the parallel resonant frequency. Influence; after the capacitor C L is connected in parallel, the resonant frequency of the circuit can be expressed as:
  • C S is the dynamic capacitance of the crystal
  • L S is the dynamic inductance of the crystal
  • C 0 is the static capacitance
  • the required compensation capacitance C x can be obtained according to the determined temperature coefficients a 1 , a 2 , a 3 and the current temperature T;
  • C x — min is the minimum value of the compensation capacitance required for the crystal to change due to temperature, and is constant;
  • obtaining a temperature compensation table corresponding to the crystal according to the determined temperature coefficient includes:
  • each temperature value is The temperature interval between the two can be set as needed.
  • the temperature interval can be 0.5°.
  • the temperature compensation table is obtained during the automatic test process before the terminal leaves the factory, and is used in the frequency fine adjustment during subsequent terminal use. It can be directly applied, that is, the terminal can directly obtain the corresponding minimum number of unit capacitors through the temperature compensation table according to the current temperature.
  • the method before the determining the temperature coefficient of the crystal, the method further includes:
  • Calibrating the frequency of the crystal oscillator circuit to calibrate the initial frequency of the crystal oscillator circuit the operation can be performed in an automated test before leaving the terminal of the crystal oscillator circuit, specifically The frequency of the automated test is completed during the coarse adjustment process;
  • the coarse adjustment of the frequency of the crystal oscillator circuit includes:
  • the method further includes: obtaining a correction coefficient k according to a ratio of a value of the calibrated control word to a value of a reference control word, that is, a value of the calibrated control word/reference control word; the k is used as an acquisition
  • the correction coefficient when the table is nonlinearly compensated; the value of the reference control word can be set according to actual needs.
  • the method further includes:
  • the frequency is calibrated to 26 MHz, and the AFC control word initial value and the slope slope are acquired; the AFC control word initial value and the slope are used to quickly search for the frequency when the terminal is powered on.
  • Step 102 Acquire a second control word according to the current AFC control word and the nonlinear compensation table.
  • This step can be implemented by a nonlinear compensation circuit in the crystal oscillator circuit
  • the method further comprises: obtaining the nonlinear compensation table according to a relationship between an AFC control word and a compensation capacitance required to correct a frequency-AFC control word curve;
  • f y ay + b; where a and b are constants, which can be set according to actual conditions;
  • the actually required compensation capacitor C' z can be obtained according to the determined AFC control word and the correction coefficient k;
  • C z_min is: the minimum value of the compensation capacitor required to compensate the nonlinearity of the frequency-AFC control word curve, which is a constant;
  • the relationship of the compensation capacitances to obtain the nonlinear compensation table includes:
  • the acquiring the second control word according to the current AFC control word and the nonlinear compensation table comprises:
  • the second control word is used to characterize the number of minimum unit capacitances required for the current AFC control word; the second compensation capacitance is represented by the minimum number of unit capacitances.
  • the method further includes: acquiring a second control word according to a relationship between a current AFC control word and an AFC control word and a compensation capacitor required to correct a frequency-AFC control word curve;
  • step 101 and step 102 are in no particular order and can be processed in parallel.
  • Step 103 Adjust the capacitor array according to the first control word and the second control word to implement tuning of the frequency of the crystal oscillator circuit.
  • This step can be implemented by a tuning circuit in the crystal oscillator circuit
  • the step includes: adding the first control word and the second control word to obtain a third control word, adjusting a size of the capacitor array according to the third control word, to achieve tuning of the frequency of the crystal oscillator circuit;
  • the third control word is used to characterize the number of minimum unit capacitances required to tune the crystal oscillator circuit.
  • a tuning method of a crystal oscillator circuit according to an embodiment of the present invention includes:
  • Step 201 Obtain a nonlinear compensation table according to a relationship between an AFC control word and a compensation capacitor required to correct a frequency-AFC control word curve;
  • determining the correction coefficient k comprises:
  • the frequency of the crystal oscillator circuit is coarsely calibrated by adjusting the size of the coarse tuning capacitor array, and a calibrated control word is obtained; in one embodiment, the error can be calibrated to less than 1 ppm;
  • the method further includes: obtaining a correction coefficient k according to a ratio of a value of the calibrated control word to a value of the reference control word; wherein the value of the reference control word can be set according to actual needs; for determining the radio frequency processing Circuit/terminal, the k is a constant.
  • Determining the number of required minimum unit capacitances corresponding to the values of the different AFC control words in the crystal oscillator circuit including:
  • the operation corresponding to obtaining the nonlinear compensation table in this step only needs to be performed when the tuning method of the crystal oscillator circuit of the present invention is first executed or in the automatic test before leaving the terminal of the crystal oscillator circuit. Yes, the follow-up can be used directly.
  • Step 202 Obtain a temperature compensation table corresponding to the crystal according to a temperature coefficient of the current crystal
  • the temperature coefficient of the crystal includes: a first temperature coefficient a 1 , a second temperature coefficient a 2 , and a third temperature coefficient a 3 ;
  • T 0 is the inflection temperature of the crystal, about 25°; the crystal may be AT cut;
  • ⁇ f c (T) represents the amount of frequency change when the temperature is T.
  • the method further includes: determining a temperature coefficient of the crystal; it should be noted that the operation is only performed in an automated test before the terminal leaves the factory;
  • the determining the temperature coefficient of the crystal includes:
  • the input resistance of the amplifier needs to match the series resonant impedance of the crystal.
  • the impedance of the amplifier and the impedance of the crystal may be mismatched during series resonance.
  • the crystal is usually operated in the parallel resonance mode. Due to the influence of the parallel capacitor C 0 , the frequency response is worse than the series resonance. Therefore, a capacitor is usually connected in parallel across the crystal to reduce the C 0 to the parallel resonant frequency. Influence; after the capacitor C L is connected in parallel, the resonant frequency of the circuit can be expressed as:
  • C S is the dynamic capacitance of the crystal
  • L S is the dynamic inductance of the crystal
  • C 0 is the static capacitance
  • the required compensation capacitance C x can be obtained according to the determined temperature coefficients a 1 , a 2 , a 3 and the current temperature T;
  • C x — min is the minimum value of the compensation capacitance required for the crystal to change due to temperature, and is constant;
  • obtaining a temperature compensation table corresponding to the crystal according to a temperature coefficient of the current crystal includes:
  • the temperature interval between each of the temperature values may be set as needed, for example, the temperature interval may be 0.5°.
  • the operation corresponding to obtaining the temperature compensation table in this step only needs to be performed when the tuning method of the crystal oscillator circuit of the present invention is first executed or in the automatic test before leaving the terminal of the crystal oscillator circuit.
  • the follow-up can be applied directly.
  • the method further includes:
  • Initialize the DBB AFC calibrate the frequency to 26MHz, obtain the initial value of the AFC control word and the slope of the slope; the initial value of the AFC control word and the slope are used to quickly search the frequency when the terminal is powered on; it should be noted that the operation is only before the terminal leaves the factory. Execute in an automated test.
  • Step 203 Acquire a first control word according to a current digital voltage signal and a temperature compensation table.
  • the current digital voltage signal is converted by an analog voltage signal input by the temperature sensing circuit through an analog-to-digital converter, and input to the temperature compensation circuit; the analog voltage signal is generated by the temperature sensing circuit. And varies with temperature, that is, the analog voltage signal and Temperature dependent, ie the digital voltage signal is temperature dependent.
  • the step includes: determining a corresponding temperature value according to the current digital voltage signal, and acquiring a first compensation capacitor corresponding to the temperature value in the temperature compensation table according to the temperature value by using a lookup table, according to the first compensation capacitor Generating a first control word; the first control word is used to represent a size of a compensation capacitor required for a current digital voltage signal; and the first compensation capacitance corresponding to the temperature value is a minimum unit corresponding to the temperature value
  • the number of capacitors, that is, the first compensation capacitor is represented by the minimum number of unit capacitors.
  • Step 204 Acquire a second control word according to the current AFC control word and the nonlinear compensation table.
  • the second control word is used to characterize the number of minimum unit capacitances required for the current AFC control word; the second compensation capacitance is represented by the minimum number of unit capacitances.
  • step 203 and step 204 is in no particular order and can be processed in parallel.
  • Step 205 Adjust the capacitor array according to the first control word and the second control word to implement tuning of the frequency of the crystal oscillator circuit.
  • the step includes: adding the first control word and the second control word to obtain a third control word, adjusting a size of the capacitor array according to the third control word, to achieve tuning of the frequency of the crystal oscillator circuit;
  • the third control word is used to characterize the number of minimum unit capacitances required to tune the crystal oscillator circuit.
  • the crystal oscillator circuit component of the embodiment of the present invention includes: a temperature compensation circuit 31, a nonlinear compensation circuit 32, and a tuning circuit 33;
  • the temperature compensation circuit 31 is configured to acquire a first control word according to a current digital voltage signal and a temperature compensation table
  • the nonlinear compensation circuit 32 is configured to acquire a second control word according to the current AFC control word and the nonlinear compensation table;
  • the tuning circuit 33 is configured to adjust the capacitor array according to the first control word and the second control word to implement tuning of the frequency of the crystal oscillator circuit.
  • the current digital voltage signal is converted from an input analog voltage signal and is temperature dependent
  • the crystal oscillator circuit further includes an analog to digital converter 34 configured to convert the input analog voltage signal to a corresponding digital voltage signal.
  • the crystal oscillator circuit further includes a processor 35 configured to determine a temperature coefficient of the crystal, and obtain a temperature compensation table corresponding to the crystal according to the determined temperature coefficient;
  • the temperature coefficient of the crystal comprises: a first temperature coefficient a 1 , a second temperature coefficient a 2 and a third temperature coefficient a 3 ;
  • T 0 is the inflection temperature of the crystal, about 25°; the crystal may be AT cut;
  • ⁇ f c (T) represents the amount of frequency change when the temperature is T.
  • the relationship obtains the temperature coefficient of the crystal; wherein, (T2- ⁇ T) ⁇ T1 ⁇ T2, T2 ⁇ T3 ⁇ (T2 + ⁇ T), T 1 is the inflection temperature of the crystal, about 25 °; the frequency difference
  • T 1 is the inflection temperature of the crystal, about 25 °
  • the correspondence between ⁇ f and the temperature coefficient can be obtained by looking up the table.
  • the input resistance of the amplifier needs to match the series resonant impedance of the crystal.
  • the impedance of the amplifier and the impedance of the crystal may be mismatched during series resonance.
  • the crystal is usually operated in the parallel resonance mode. Due to the influence of the parallel capacitor C 0 , the frequency response is worse than the series resonance. Therefore, a capacitor is usually connected in parallel across the crystal to reduce the C 0 to the parallel resonant frequency. Influence; after the capacitor C L is connected in parallel, the resonant frequency of the circuit can be expressed as:
  • C S is the dynamic capacitance of the crystal
  • L S is the dynamic inductance of the crystal
  • C 0 is the static capacitance
  • the required compensation capacitance C x can be obtained according to the determined temperature coefficients a 1 , a 2 , a 3 and the current temperature T;
  • C x — min is the minimum value of the compensation capacitance required for the crystal to change due to temperature, and is constant;
  • the processor 35 obtains a temperature compensation table corresponding to the crystal according to the determined temperature coefficient, including:
  • the processor 35 obtains the minimum unit capacitance required for each crystal temperature according to the relationship between the determined temperature and the compensation capacitance required by the crystal, thereby obtaining a temperature compensation table of the crystal;
  • the temperature interval between each temperature value may be set according to requirements, for example, the temperature interval may be 0.5°; the temperature compensation table is obtained during the subsequent terminal use during the automatic test process before the terminal leaves the factory.
  • the frequency fine adjustment can be directly applied, that is, the terminal can directly obtain the corresponding minimum unit capacitance number through the temperature compensation table according to the current temperature.
  • the crystal oscillator circuit further includes a frequency coarse adjustment circuit 36 configured to coarsely adjust a frequency of the crystal oscillator circuit to calibrate an initial frequency of the crystal oscillator circuit; configured to be based on a current transmission
  • the carrier signal transmitted by the device TX calculates a reference clock error, and adjusts the frequency of the crystal oscillator circuit by adjusting the size of the ATE Calibration SC array to obtain a calibrated control word; Medium, calibrated to an error of less than 1 ppm.
  • the frequency coarse adjustment circuit 36 is further configured to obtain a correction coefficient according to a ratio of a value of the calibrated control word to a value of a reference control word, that is, a value of the calibrated control word/a value of the reference control word. k; the k is used as a correction coefficient when acquiring the nonlinear compensation table; the value of the reference control word can be set according to actual needs.
  • the temperature compensation circuit 31 is configured to be based on a current digital voltage signal. No. determining a corresponding temperature value, and obtaining a first compensation capacitor corresponding to the temperature value in the temperature compensation table according to the temperature value, and generating a first control word according to the first compensation capacitor; a control word is used to represent a size of a compensation capacitor required for the current digital voltage signal; the first compensation capacitor corresponding to the temperature value is a minimum unit capacitance corresponding to the temperature value, that is, the first compensation The capacitance is represented by the number of minimum unit capacitances.
  • the nonlinear compensation circuit 32 is configured to acquire a second compensation capacitor corresponding to the AFC control word in the nonlinear compensation table according to the current AFC control word by using a lookup table, according to the second The compensation capacitor generates a second control word;
  • the second control word is used to characterize the number of minimum unit capacitances required for the current AFC control word; the second compensation capacitance is represented by the minimum number of unit capacitances.
  • the processor 35 is further configured to acquire the nonlinear compensation table according to a relationship between an AFC control word and a compensation capacitor required to correct a frequency-AFC control word curve;
  • f y ay + b; where a and b are constants, which can be set according to actual conditions;
  • the actually required compensation capacitor C' z can be obtained according to the determined AFC control word and the correction coefficient k;
  • C z_min is: the minimum value of the compensation capacitor required to compensate the nonlinearity of the frequency-AFC control word curve, which is a constant;
  • the processor 35 obtains the nonlinear compensation table according to the relationship between the AFC control word and the compensation capacitance required to correct the frequency-AFC control word curve, including:
  • the processor 35 determines, according to the determined correction coefficient k, the number of required minimum unit capacitances corresponding to the values of different AFC control words in the crystal oscillator circuit, thereby obtaining the nonlinear compensation table; After the compensation table is obtained in the automatic test process before leaving the factory, it can be directly applied in the frequency fine adjustment during the subsequent terminal use.
  • the nonlinear compensation circuit 32 is further configured to acquire a second control word according to a relationship between a current AFC control word and an AFC control word and a compensation capacitor required to correct a frequency-AFC control word curve;
  • the non-linear compensation circuit 32 obtains the second control word according to the relationship between the current AFC control word and the AFC control word and the compensation capacitance required to correct the frequency-AFC control word curve, including:
  • the nonlinear compensation circuit 32 is based on the current AFC control word and Obtaining a corrected frequency curve -AFC control word required compensation capacitor C 'z, according to the compensation capacitor C' z to obtain a minimum number of units corresponding to the capacitance, and generates a second control word obtained based on the minimum number of unit capacitances.
  • the tuning circuit 33 is configured to add the first control word and the second control word to obtain a third control word, and adjust the size of the capacitor array according to the third control word to implement tuning.
  • the third control word is used to characterize the number of minimum unit capacitances required to tune the crystal oscillator circuit.
  • the tuning method of the crystal oscillator circuit described above is implemented in the form of a software function module and sold or used as a stand-alone product, it may also be stored in a computer readable storage medium.
  • the technical solution of the embodiments of the present invention may be embodied in the form of a software product in essence or in the form of a software product stored in a storage medium, including a plurality of instructions.
  • a computer device (which may be a personal computer, server, or network device, etc.) is caused to perform all or part of the methods described in various embodiments of the present invention.
  • the foregoing storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read only memory (ROM), a magnetic disk, or an optical disk.
  • program codes such as a USB flash drive, a mobile hard disk, a read only memory (ROM), a magnetic disk, or an optical disk.
  • an embodiment of the present invention further provides a computer storage medium, where the computer storage medium stores a computer program for performing the tuning method of the crystal oscillator circuit of the embodiment of the present invention.
  • the embodiment of the invention obtains the first control word according to the current digital voltage signal and the temperature compensation table; acquires the second control word according to the current AFC control word and the nonlinear compensation table; according to the first control word and the second control word pair
  • the array of capacitors is adjusted to achieve tuning of the frequency of the crystal oscillator circuit. In this way, by tuning the crystal oscillator circuit according to the current digital voltage signal and the control word generated by the current AFC control word, the frequency accuracy and temperature characteristics of the crystal oscillator circuit can be improved, the user experience is enhanced, and the reliability is high. low cost.

Abstract

一种晶体振荡器电路的调谐方法、晶体振荡器电路及存储介质，所述晶体振荡器电路的调谐方法包括：依据当前的数字电压信号及温度补偿表获取第一控制字（101）；依据当前的自动频率控制（AFC）控制字及非线性补偿表获取第二控制字（102）；依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率（103）。

Description

晶体振荡器电路、晶体振荡器电路的调谐方法及存储介质 技术领域
本发明涉及晶体振荡器技术领域，尤其涉及一种晶体振荡器电路、晶体振荡器电路的调谐方法及存储介质。
背景技术
数字补偿晶体振荡器(DCXO，Digitally Compensated Crystal Oscillator)电路在现代无线通信芯片系统中得到广泛应用，通常由以下几部分组成：提供振荡所需负阻的振荡放大器，保证起振的振幅检测与控制电路，有的设计还会加上温度补偿电路来修正温度变化带来的振荡频率的漂移。
现有技术中实现晶体振荡器电路调谐的方法大多实现起来电路庞大复杂、频率准确度不高且实现成本较高；因此，提供一种晶体振荡器电路及其调谐方案，能够提高晶体振荡器电路的频率准确度，且可靠性高、成本低，已成为亟待解决的问题。
发明内容
有鉴于此，本发明实施例期望提供一种晶体振荡器电路、晶体振荡器电路的调谐方法及存储介质，能够提高晶体振荡器电路的频率准确度，增强用户体验，且可靠性高、成本低。
为达到上述目的，本发明实施例的技术方案是这样实现的：
本发明实施例提供了一种晶体振荡器电路的调谐方法，所述方法包括：
依据当前的数字电压信号及温度补偿表获取第一控制字；
依据当前的自动频率控制(AFC，Automatic Frequency Control)控制字及非线性补偿表获取第二控制字；
依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐 所述晶体振荡器电路的频率。
上述方案中，所述当前的数字电压信号由输入的模拟电压信号转换得到，且与温度相关。
上述方案中，所述依据当前的数字电压信号及温度补偿表获取第一控制字之前，所述方法还包括：
确定晶体的温度系数，并依据确定的温度系数获取对应所述晶体的温度补偿表。
上述方案中，所述依据当前的数字电压信号及温度补偿表获取第一控制字包括：
依据当前的数字电压信号确定对应的温度值，并依据所述温度值采用查找表的方式获取温度补偿表中对应所述温度值的第一补偿电容，依据所述第一补偿电容产生第一控制字。
上述方案中，所述依据当前的AFC控制字及非线性补偿表获取第二控制字，包括：
依据当前的AFC控制字采用查找表的方式获取非线性补偿表中对应所述AFC控制字的第二补偿电容，依据所述第二补偿电容产生第二控制字。
上述方案中，所述依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率，包括：
将所述第一控制字及第二控制字相加获得第三控制字，依据所述第三控制字调节电容阵列的大小，以实现调谐所述晶体振荡器电路的频率。
本发明实施例还提供了一种晶体振荡器电路，所述晶体振荡器电路包括：温度补偿电路、非线性补偿电路及调谐电路；其中，
所述温度补偿电路，配置为依据当前的数字电压信号及温度补偿表获取第一控制字；
所述非线性补偿电路，配置为依据当前的AFC控制字及非线性补偿表 获取第二控制字；
所述调谐电路，配置为依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率。
上述方案中，所述当前的数字电压信号由输入的模拟电压信号转换得到，且与温度相关；
相应的，所述晶体振荡器电路还包括模数转换器，配置为将输入的模拟电压信号转换得到对应的数字电压信号。
上述方案中，所述晶体振荡器电路还包括处理器，配置为确定晶体的温度系数，并依据确定的温度系数获取对应所述晶体的温度补偿表。
上述方案中，所述温度补偿电路，配置为依据当前的数字电压信号确定对应的温度值，并依据所述温度值采用查找表的方式获取温度补偿表中对应所述温度值的第一补偿电容，依据所述第一补偿电容产生第一控制字。
上述方案中，所述非线性补偿电路，配置为依据当前的AFC控制字采用查找表的方式获取非线性补偿表中对应所述AFC控制字的第二补偿电容，依据所述第二补偿电容产生第二控制字。
上述方案中，所述调谐电路，配置为将所述第一控制字及第二控制字相加获得第三控制字，依据所述第三控制字调节电容阵列的大小，以实现调谐所述晶体振荡器电路的频率。
本发明实施例还提供了一种计算机存储介质，所述计算机存储介质存储有计算机程序，该计算机程序配置为执行本发明实施例的上述晶体振荡器电路的调谐方法。
本发明实施例所提供的晶体振荡器电路、晶体振荡器电路的调谐方法及存储介质，依据当前的数字电压信号及温度补偿表获取第一控制字；依据当前的AFC控制字及非线性补偿表获取第二控制字；依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的 频率。如此，通过依据当前的数字电压信号及当前的AFC控制字产生的控制字实现晶体振荡器电路的调谐，能够提高晶体振荡器电路的频率准确度及温度特性，增强用户体验，且可靠性高、成本低。
附图说明
图1为本发明实施例一晶体振荡器电路的调谐方法流程示意图；
图2为本发明实施例二晶体振荡器电路的调谐方法流程示意图；
图3为本发明实施例晶体振荡器电路组成结构示意图。
具体实施方式
在本发明实施例中，依据当前的数字电压信号及温度补偿表获取第一控制字；依据当前的AFC控制字及非线性补偿表获取第二控制字；依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率。
实施例一
图1所示为本发明实施例一晶体振荡器电路的调谐方法流程示意图，如图1所示，本发明实施例晶体振荡器电路的调谐方法包括：
步骤101：依据当前的数字电压信号及温度补偿表获取第一控制字；
本步骤可由晶体振荡器电路中的温度补偿电路实现；
本步骤包括：依据当前的数字电压信号确定对应的温度值，并依据所述温度值采用查找表的方式获取温度补偿表中对应所述温度值的第一补偿电容，依据所述第一补偿电容产生第一控制字；所述第一控制字用于表征对应当前的数字电压信号所需的补偿电容的大小；所述对应所述温度值的第一补偿电容为对应所述温度值的最小单位电容数目，即所述第一补偿电容通过最小单位电容数目表示。
这里，所述当前的数字电压信号由温度传感电路输入的模拟电压信号 经模数转换器转换得到，并输入至所述温度补偿电路；所述模拟电压信号由所述温度传感电路产生，且随温度变化而变化，即所述模拟电压信号与温度相关，也即所述数字电压信号与温度相关，其具体关系依据当前采用的温度传感器确定，例如当前的温度传感器采用热敏电阻实现时，所述数字电压信号与温度近似线性关系；
依据当前的数字电压信号确定对应的温度值包括：依据当前的数字电压信号及数字电压信号与温度值的对应关系确定对应的温度值。
在一实施例中，所述依据当前的数字电压信号及温度补偿表获取第一控制字之前，所述方法还包括：
确定晶体的温度系数，并依据确定的温度系数获取对应所述晶体的温度补偿表；该操作可在包含所述晶体振荡器电路的终端出厂前的自动化测试中完成，具体在自动化测试的频率粗调过程中完成；
其中，所述晶体的温度系数包括：第一温度系数a1、第二温度系数a2及第三温度系数a3；
晶体的频率-温度特性可表示为：Δfc(T)＝a3(T-T0)3+a2(T-T0)2+a1(T-T0)；
其中，T0为晶体的拐点温度，约为25°；所述晶体可以为AT切型；
Δfc(T)表示温度为T时的频率变化量。
在一实施例中，所述确定晶体的温度系数包括：
获取晶体温度为T1及T3时的频率差Δf＝f(T3)-f(T1)，依据所述频率差Δf与温度系数的对应关系获得所述晶体的温度系数；其中，(T2-ΔT)<T1<T2，T2<T3<(T2+ΔT)，T1为所述晶体的拐点温度，约为25°；所述频率差Δf与温度系数的对应关系可通过查表获得。
在晶体振荡器电路中，放大器的输入电阻需要和晶体的串联谐振阻抗相匹配，但是由于放大器的输入阻抗通常都比较高，所以在串联谐振时放大器的阻抗和晶体的阻抗可能出现不匹配，为了解决此问题，通常让晶体 工作在并联谐振模式，由于受到并联电容C0的影响，其频率响应比串联谐振差，因此通常在晶体的两端并联一个电容，以降低C0对并联谐振频率的影响；在并联了电容CL后，电路的谐振频率可以表示为：
Figure PCTCN2016073540-appb-000001
其中，CS为晶体的动态电容；LS为晶体的动态电感；C0为静态电容；由串联谐振频率
Figure PCTCN2016073540-appb-000002
并联谐振频率
Figure PCTCN2016073540-appb-000003
可得，
Figure PCTCN2016073540-appb-000004
通过上式可知，可以通过调整负载电容CL，来实现晶振振荡频率的变化，即要想补偿晶体本身温度变化引起的频率变化，需要在温度变化的时候同步改变负载电容；假设负载CL变为Cx时刚好抵消掉晶体本身温度变化引起的频率变化，则有
Figure PCTCN2016073540-appb-000005
由fL-fx＝Δfc可得
Figure PCTCN2016073540-appb-000006
即
Figure PCTCN2016073540-appb-000007
进而可以得到补偿电容和温度的关系为：
Figure PCTCN2016073540-appb-000008
因此，通过上式可得，依据确定的温度系数a1、a2、a3及当前的温度T可获得需要的补偿电容Cx；
令最小单位电容为Cunit，需要补偿的电容个数为num_Cunit，可得：
Figure PCTCN2016073540-appb-000009
其中，Cx_min为晶体因温度变化所需补偿电容的最小值，为常量；
通过上式可知，对于一个确定的晶体，获得该晶体的温度系数后，对应每一个温度值都可获得其需要的补偿电容的大小及需要的最小单位电容的数目；
综上所述，依据确定的温度系数获取对应所述晶体的温度补偿表包括：
依据确定的温度与所述晶体需要的补偿电容的关系，获得所述晶体在每个温度值需要的最小单位电容的数目，进而得到所述晶体的温度补偿表；这里，所述每个温度值之间的温度间隔可以依据需要进行设定，例如所述温度间隔可以为0.5°；所述温度补偿表在终端出厂前的自动化测试过程中获得后，在后续终端使用过程中的频率精调中可直接应用，即终端可依据当前的温度通过所述温度补偿表直接获得对应所需的最小单位电容数目。
在一实施例中，所述确定晶体的温度系数之前，所述方法还包括：
对晶体振荡器电路的频率进行粗调(Coarse Calibration)，以校准所述晶体振荡器电路的初始频率；该操作可在包含所述晶体振荡器电路的终端出厂前的自动化测试中完成，具体在自动化测试的频率粗调过程中完成；
其中，对晶体振荡器电路的频率进行粗调包括：
依据当前发射器TX发射的载波信号计算参考时钟误差，并通过调节粗调谐电容阵列的大小实现对所述晶体振荡器电路的频率的校准，获得校准后的控制字；在一实施例中，可校准到误差小于1ppm；
这里，所述方法还包括：依据校准后控制字的值与参考控制字的值的比值，即校准后控制字的值/参考控制字的值，获得校正系数k；所述k用于作为获取非线性补偿表时的校正系数；所述参考控制字的值可以依据实际需要进行设定。
在一实施例中，所述确定晶体的温度系数，并依据确定的温度系数获取对应所述晶体的温度补偿表之后，所述方法还包括：
对数字基带DBB AFC初始化，将频率校准到26MHz，获取AFC控制字初始值和斜率slope；所述AFC控制字初始值和slope用于终端开机时快速搜索频率。
步骤102：依据当前的AFC控制字及非线性补偿表获取第二控制字；
本步骤可由晶体振荡器电路中的非线性补偿电路实现；
本步骤之前，所述方法还包括：依据AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系获取所述非线性补偿表；
设AFC控制字的值为y，预失真后的控制字为z，那么有：
Figure PCTCN2016073540-appb-000010
若f-y曲线是线性的，则fy＝ay+b；其中，a、b为常量，可依据实际情况进行设定；
令fz＝fy可得：
Figure PCTCN2016073540-appb-000011
经校正系数k校正后可得：
Figure PCTCN2016073540-appb-000012
通过上式可得，依据确定的AFC控制字及校正系数k可获得实际需要的补偿电容C’z；
令最小单位电容为Cunit，需要补偿的电容个数为z，可得：
Figure PCTCN2016073540-appb-000013
其中，Cz_min为：为补偿频率-AFC控制字曲线的非线性所需补偿电容的最小值，为常量；
综上所述，所述依据AFC控制字与校正频率-AFC控制字曲线所需的 补偿电容的关系获取所述非线性补偿表包括：
依据确定的校正系数k确定在晶体振荡器电路中，不同的AFC控制字的值对应的所需最小单位电容的数目，进而得到所述非线性补偿表；这里所述非线性补偿表在终端出厂前的自动化测试过程中获得后，在后续终端使用过程中的频率精调中可直接应用；
在一实施例中，所述依据当前的AFC控制字及非线性补偿表获取第二控制字，包括：
依据当前的AFC控制字采用查找表的方式获取非线性补偿表中对应所述AFC控制字的第二补偿电容，依据所述第二补偿电容产生第二控制字；
所述第二控制字用于表征对应当前的AFC控制字所需的最小单位电容的数目；所述第二补偿电容通过最小单位电容数目表示。
在一实施例中，所述方法还包括：依据当前的AFC控制字及AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系获取第二控制字；
这里，所述AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系为：
Figure PCTCN2016073540-appb-000014
所述依据当前的AFC控制字及AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系获取第二控制字，包括：
依据当前的AFC控制字及
Figure PCTCN2016073540-appb-000015
获得校正频率-AFC控制字曲线所需的补偿电容C'z，依据所述补偿电容C'z获得对应的最小单位电容的数目，并依据获得的最小单位电容的数目产生第二控制字。
需要说明的是，步骤101与步骤102的操作顺序不分先后，可并行处理。
步骤103：依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率；
本步骤可由晶体振荡器电路中的调谐电路实现；
本步骤包括：将所述第一控制字及第二控制字相加获得第三控制字，依据所述第三控制字调节电容阵列的大小，以实现调谐所述晶体振荡器电路的频率；这里，所述第三控制字用于表征调谐所述晶体振荡器电路所需的最小单位电容的数目。
实施例二
图2为本发明实施例二晶体振荡器电路的调谐方法流程示意图；如图2所示，本发明实施例晶体振荡器电路的调谐方法包括：
步骤201：依据AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系获取非线性补偿表；
确定校正系数k，并依据确定的校正系数k确定在晶体振荡器电路中，不同的AFC控制字的值对应的所需最小单位电容的数目，进而得到所述非线性补偿表；
其中，所述确定校正系数k包括：
通过调节粗调谐电容阵列的大小对所述晶体振荡器电路的频率进行粗校准，并获得校准后的控制字；在一实施例中，可校准到误差小于1ppm；
这里，所述方法还包括：依据校准后控制字的值与参考控制字的值的比值获得校正系数k；其中，所述参考控制字的值可以依据实际需要进行设定；对于确定的射频处理电路/终端，所述k为常量。
确定在晶体振荡器电路中，不同的AFC控制字的值对应的所需最小单位电容的数目，包括：
依据
Figure PCTCN2016073540-appb-000016
确定在晶体振荡器电路中，不同的AFC控制字的值对应的所需补偿电容的大小C’z，并依据
Figure PCTCN2016073540-appb-000017
获得对应的所需最小单位电容的数目；
其中，y为AFC控制字；
Figure PCTCN2016073540-appb-000018
为串联谐振频率；CS为晶体的动态电容；C0为静态电容；C’z为对应AFC控制字y所需的补偿电容的大小；a、b为常量，可依据实际情况进行设定；Cz_min为：为补偿频率-AFC控制字曲线的非线性所需补偿电容的最小值，为常量；Cunit为最小单位电容。
需要说明的是，本步骤获得非线性补偿表对应的操作仅需在首次执行本发明晶体振荡器电路的调谐方法时执行或在包含所述晶体振荡器电路的终端出厂前的自动化测试中完成即可，后续可直接使用。
步骤202：依据当前晶体的温度系数获取对应所述晶体的温度补偿表；
这里，所述晶体的温度系数包括：第一温度系数a1、第二温度系数a2及第三温度系数a3；
晶体的频率-温度特性可表示为：Δfc(T)＝a3(T-T0)3+a2(T-T0)2+a1(T-T0)；
其中，T0为晶体的拐点温度，约为25°；所述晶体可以为AT切型；
Δfc(T)表示温度为T时的频率变化量。
本步骤之前，所述方法还包括：确定晶体的温度系数；需要说明的是本操作仅在终端出厂前的自动化测试中执行即可；
所述确定晶体的温度系数包括：
获取晶体温度为T1及T3时的频率差Δf＝f(T3)-f(T1)，依据所述频率差Δf与温度系数的对应关系获得所述晶体的温度系数；其中，(T2-ΔT)<T1<T2，T2<T3<(T2+ΔT)，T1为所述晶体的拐点温度，约为25°；所述频率差Δf与温度系数的对应关系可通过查表获得；对于确定的晶体，对应的温度系数为常数。
在晶体振荡器电路中，放大器的输入电阻需要和晶体的串联谐振阻抗相匹配，但是由于放大器的输入阻抗通常都比较高，所以在串联谐振时放大器的阻抗和晶体的阻抗可能出现不匹配，为了解决此问题，通常让晶体 工作在并联谐振模式，由于受到并联电容C0的影响，其频率响应比串联谐振差，因此通常在晶体的两端并联一个电容，以降低C0对并联谐振频率的影响；在并联了电容CL后，电路的谐振频率可以表示为：
Figure PCTCN2016073540-appb-000019
其中，CS为晶体的动态电容；LS为晶体的动态电感；C0为静态电容；由串联谐振频率
Figure PCTCN2016073540-appb-000020
并联谐振频率
Figure PCTCN2016073540-appb-000021
可得，
Figure PCTCN2016073540-appb-000022
通过上式可知，可以通过调整负载电容CL，来实现晶振振荡频率的变化，即要想补偿晶体本身温度变化引起的频率变化，需要在温度变化的时候同步改变负载电容；假设负载CL变为Cx时刚好抵消掉晶体本身温度变化引起的频率变化，则有
Figure PCTCN2016073540-appb-000023
由fL-fx＝Δfc可得
Figure PCTCN2016073540-appb-000024
即
Figure PCTCN2016073540-appb-000025
进而可以得到补偿电容和温度的关系为：
Figure PCTCN2016073540-appb-000026
因此，通过上式可得，依据确定的温度系数a1、a2、a3及当前的温度T可获得需要的补偿电容Cx；
令最小单位电容为Cunit，需要补偿的电容个数为num_Cunit，可得：
Figure PCTCN2016073540-appb-000027
其中，Cx_min为晶体因温度变化所需补偿电容的最小值，为常量；
通过上式可知，对于一个确定的晶体，获得该晶体的温度系数后，对应每一个温度值都可获得其需要的补偿电容的大小及需要的最小单位电容的数目；
综上所述，依据当前晶体的温度系数获取对应所述晶体的温度补偿表包括：
依据
Figure PCTCN2016073540-appb-000028
获得所述晶体在每个温度值需要的补偿电容的大小Cx，并依据
Figure PCTCN2016073540-appb-000029
获得对应的最小单位电容的数目，进而得到所述晶体的温度补偿表；这里，所述每个温度值之间的温度间隔可以依据需要进行设定，例如所述温度间隔可以为0.5°。
需要说明的是，本步骤获得温度补偿表对应的操作仅需在首次执行本发明晶体振荡器电路的调谐方法时执行或在包含所述晶体振荡器电路的终端出厂前的自动化测试中完成即可，后续可直接应用。
在一实施例中，本步骤之后，所述方法还包括：
对DBB AFC初始化，将频率校准到26MHz，获取AFC控制字初始值和斜率slope；所述AFC控制字初始值和slope用于终端开机时快速搜索频率；需要说明的是本操作仅在终端出厂前的自动化测试中执行即可。
步骤203：依据当前的数字电压信号及温度补偿表获取第一控制字；
这里，所述当前的数字电压信号由温度传感电路输入的模拟电压信号经模数转换器转换得到，并输入至所述温度补偿电路；所述模拟电压信号由所述温度传感电路产生，且随温度变化而变化，即所述模拟电压信号与 温度相关，也即所述数字电压信号与温度相关。
本步骤包括：依据当前的数字电压信号确定对应的温度值，并依据所述温度值采用查找表的方式获取温度补偿表中对应所述温度值的第一补偿电容，依据所述第一补偿电容产生第一控制字；所述第一控制字用于表征对应当前的数字电压信号所需的补偿电容的大小；所述对应所述温度值的第一补偿电容为对应所述温度值的最小单位电容数目，即所述第一补偿电容通过最小单位电容数目表示。
步骤204：依据当前的AFC控制字及非线性补偿表获取第二控制字；
本步骤包括：依据当前的AFC控制字采用查找表的方式获取非线性补偿表中对应所述AFC控制字的第二补偿电容，依据所述第二补偿电容产生第二控制字；
所述第二控制字用于表征对应当前的AFC控制字所需的最小单位电容的数目；所述第二补偿电容通过最小单位电容数目表示。
需要说明的是，步骤203与步骤204的操作顺序不分先后，可并行处理。
步骤205：依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率；
本步骤包括：将所述第一控制字及第二控制字相加获得第三控制字，依据所述第三控制字调节电容阵列的大小，以实现调谐所述晶体振荡器电路的频率；这里，所述第三控制字用于表征调谐所述晶体振荡器电路所需的最小单位电容的数目。
实施例三
图3为本发明实施例晶体振荡器电路组成结构示意图；如图3所示，本发明实施例晶体振荡器电路组成包括：温度补偿电路31、非线性补偿电路32及调谐电路33；其中，
所述温度补偿电路31，配置为依据当前的数字电压信号及温度补偿表获取第一控制字；
所述非线性补偿电路32，配置为依据当前的AFC控制字及非线性补偿表获取第二控制字；
所述调谐电路33，配置为依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率。
在一实施例中，所述当前的数字电压信号由输入的模拟电压信号转换得到，且与温度相关；
相应的，所述晶体振荡器电路还包括模数转换器34，配置为将输入的模拟电压信号转换得到对应的数字电压信号。
在一实施例中，所述晶体振荡器电路还包括处理器35，配置为确定晶体的温度系数，并依据确定的温度系数获取对应所述晶体的温度补偿表；
其中，所述晶体的温度系数包括：第一温度系数a1、第二温度系数a2及第三温度系数a3；
晶体的频率-温度特性可表示为：Δfc(T)＝a3(T-T0)3+a2(T-T0)2+a1(T-T0)；
其中，T0为晶体的拐点温度，约为25°；所述晶体可以为AT切型；
Δfc(T)表示温度为T时的频率变化量。
在一实施例中，所述处理器35，配置为获取晶体温度为T1及T3时的频率差Δf＝f(T3)-f(T1)，依据所述频率差Δf与温度系数的对应关系获得所述晶体的温度系数；其中，(T2-ΔT)<T1<T2，T2<T3<(T2+ΔT)，T1为所述晶体的拐点温度，约为25°；所述频率差Δf与温度系数的对应关系可通过查表获得。
在晶体振荡器电路中，放大器的输入电阻需要和晶体的串联谐振阻抗相匹配，但是由于放大器的输入阻抗通常都比较高，所以在串联谐振时放大器的阻抗和晶体的阻抗可能出现不匹配，为了解决此问题，通常让晶体 工作在并联谐振模式，由于受到并联电容C0的影响，其频率响应比串联谐振差，因此通常在晶体的两端并联一个电容，以降低C0对并联谐振频率的影响；在并联了电容CL后，电路的谐振频率可以表示为：
Figure PCTCN2016073540-appb-000030
其中，CS为晶体的动态电容；LS为晶体的动态电感；C0为静态电容；由串联谐振频率
Figure PCTCN2016073540-appb-000031
并联谐振频率
Figure PCTCN2016073540-appb-000032
可得，
Figure PCTCN2016073540-appb-000033
通过上式可知，可以通过调整负载电容CL，来实现晶振振荡频率的变化，即要想补偿晶体本身温度变化引起的频率变化，需要在温度变化的时候同步改变负载电容；假设负载CL变为Cx时刚好抵消掉晶体本身温度变化引起的频率变化，则有
Figure PCTCN2016073540-appb-000034
由fL-fx＝Δfc可得
Figure PCTCN2016073540-appb-000035
即
Figure PCTCN2016073540-appb-000036
进而可以得到补偿电容和温度的关系为：
Figure PCTCN2016073540-appb-000037
因此，通过上式可得，依据确定的温度系数a1、a2、a3及当前的温度T可获得需要的补偿电容Cx；
令最小单位电容为Cunit，需要补偿的电容个数为num_Cunit，可得：
Figure PCTCN2016073540-appb-000038
其中，Cx_min为晶体因温度变化所需补偿电容的最小值，为常量；
通过上式可知，对于一个确定的晶体，获得该晶体的温度系数后，对应每一个温度值都可获得其需要的补偿电容的大小及需要的最小单位电容的数目；
综上所述，所述处理器35依据确定的温度系数获取对应所述晶体的温度补偿表包括：
所述处理器35依据确定的温度与所述晶体需要的补偿电容的关系，获得所述晶体在每个温度值需要的最小单位电容的数目，进而得到所述晶体的温度补偿表；这里，所述每个温度值之间的温度间隔可以依据需要进行设定，例如所述温度间隔可以为0.5°；所述温度补偿表在终端出厂前的自动化测试过程中获得后，在后续终端使用过程中的频率精调中可直接应用，即终端可依据当前的温度通过所述温度补偿表直接获得对应所需的最小单位电容数目。
在一实施例中，所述晶体振荡器电路还包括频率粗调电路36，配置为对晶体振荡器电路的频率进行粗调，以校准所述晶体振荡器电路的初始频率；配置为依据当前发射器TX发射的载波信号计算参考时钟误差，并通过调节粗调谐电容阵列(ATE Calibration SC array)的大小实现对所述晶体振荡器电路的频率的校准，获得校准后的控制字；在一实施例中，可校准到误差小于1ppm。
在一实施例中，所述频率粗调电路36，还配置为依据校准后控制字的值与参考控制字的值的比值，即校准后控制字的值/参考控制字的值，获得校正系数k；所述k用于作为获取非线性补偿表时的校正系数；所述参考控制字的值可以依据实际需要进行设定。
在一实施例中，所述温度补偿电路31，配置为依据当前的数字电压信 号确定对应的温度值，并依据所述温度值采用查找表的方式获取温度补偿表中对应所述温度值的第一补偿电容，依据所述第一补偿电容产生第一控制字；所述第一控制字用于表征对应当前的数字电压信号所需的补偿电容的大小；所述对应所述温度值的第一补偿电容为对应所述温度值的最小单位电容数目，即所述第一补偿电容通过最小单位电容数目表示。
在一实施例中，所述非线性补偿电路32，配置为依据当前的AFC控制字采用查找表的方式获取非线性补偿表中对应所述AFC控制字的第二补偿电容，依据所述第二补偿电容产生第二控制字；
所述第二控制字用于表征对应当前的AFC控制字所需的最小单位电容的数目；所述第二补偿电容通过最小单位电容数目表示。
在一实施例中，所述处理器35，还配置为依据AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系获取所述非线性补偿表；
设AFC控制字的值为y，预失真后的控制字为z，那么有：
Figure PCTCN2016073540-appb-000039
若f-y曲线是线性的，则fy＝ay+b；其中，a、b为常量，可依据实际情况进行设定；
令fz＝fy可得：
Figure PCTCN2016073540-appb-000040
经校正系数k校正后可得：
Figure PCTCN2016073540-appb-000041
通过上式可得，依据确定的AFC控制字及校正系数k可获得实际需要的补偿电容C’z；
令最小单位电容为Cunit，需要补偿的电容个数为z，可得：
Figure PCTCN2016073540-appb-000042
其中，Cz_min为：为补偿频率-AFC控制字曲线的非线性所需补偿电容的最小值，为常量；
综上所述，所述处理器35依据AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系获取所述非线性补偿表包括：
所述处理器35依据确定的校正系数k确定在晶体振荡器电路中，不同的AFC控制字的值对应的所需最小单位电容的数目，进而得到所述非线性补偿表；这里所述非线性补偿表在终端出厂前的自动化测试过程中获得后，在后续终端使用过程中的频率精调中可直接应用。
在一实施例中，所述非线性补偿电路32，还配置为依据当前的AFC控制字及AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系获取第二控制字；
这里，所述AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系为：
Figure PCTCN2016073540-appb-000043
所述非线性补偿电路32依据当前的AFC控制字及AFC控制字与校正频率-AFC控制字曲线所需的补偿电容的关系获取第二控制字，包括：
所述非线性补偿电路32依据当前的AFC控制字及
Figure PCTCN2016073540-appb-000044
获得校正频率-AFC控制字曲线所需的补偿电容C'z，依据所述补偿电容C'z获得对应的最小单位电容的数目，并依据获得的最小单位电容的数目产生第二控制字。
在一实施例中，所述调谐电路33，配置为将所述第一控制字及第二控制字相加获得第三控制字，依据所述第三控制字调节电容阵列的大小，以实现调谐所述晶体振荡器电路的频率；
这里，所述第三控制字用于表征调谐所述晶体振荡器电路所需的最小单位电容的数目。
本发明实施例中，如果以软件功能模块的形式实现上述晶体振荡器电路的调谐方法，并作为独立的产品销售或使用时，也可以存储在一个计算机可读取存储介质中。基于这样的理解，本发明实施例的技术方案本质上或者说对现有技术做出贡献的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机、服务器、或者网络设备等)执行本发明各个实施例所述方法的全部或部分。而前述的存储介质包括：U盘、移动硬盘、只读存储器(Read Only Memory，ROM)、磁碟或者光盘等各种可以存储程序代码的介质。这样，本发明实施例不限制于任何特定的硬件和软件结合。
相应地，本发明实施例还提供一种计算机存储介质，该计算机存储介质中存储有计算机程序，该计算机程序用于执行本发明实施例的上述晶体振荡器电路的调谐方法。
以上所述仅为本发明的较佳实施例而已，并非用于限定本发明的保护范围。
工业实用性
本发明实施例依据当前的数字电压信号及温度补偿表获取第一控制字；依据当前的AFC控制字及非线性补偿表获取第二控制字；依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率。如此，通过依据当前的数字电压信号及当前的AFC控制字产生的控制字实现晶体振荡器电路的调谐，能够提高晶体振荡器电路的频率准确度及温度特性，增强用户体验，且可靠性高、成本低。

Claims (13)

  1. 一种晶体振荡器电路的调谐方法，所述方法包括：
    依据当前的数字电压信号及温度补偿表获取第一控制字；
    依据当前的自动频率控制AFC控制字及非线性补偿表获取第二控制字；
    依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率。
  2. 根据权利要求1所述方法，其中，所述当前的数字电压信号由输入的模拟电压信号转换得到，且与温度相关。
  3. 根据权利要求1或2所述方法，其中，所述依据当前的数字电压信号及温度补偿表获取第一控制字之前，所述方法还包括：
    确定晶体的温度系数，并依据确定的温度系数获取对应所述晶体的温度补偿表。
  4. 根据权利要求1或2所述方法，其中，所述依据当前的数字电压信号及温度补偿表获取第一控制字包括：
    依据当前的数字电压信号确定对应的温度值，并依据所述温度值采用查找表的方式获取温度补偿表中对应所述温度值的第一补偿电容，依据所述第一补偿电容产生第一控制字。
  5. 根据权利要求1或2所述方法，其中，所述依据当前的AFC控制字及非线性补偿表获取第二控制字，包括：
    依据当前的AFC控制字采用查找表的方式获取非线性补偿表中对应所述AFC控制字的第二补偿电容，依据所述第二补偿电容产生第二控制字。
  6. 根据权利要求1或2所述方法，其中，所述依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率，包括：
    将所述第一控制字及第二控制字相加获得第三控制字，依据所述第三控制字调节电容阵列的大小，以实现调谐所述晶体振荡器电路的频率。
  7. 一种晶体振荡器电路，所述晶体振荡器电路包括：温度补偿电路、非线性补偿电路及调谐电路；其中，
    所述温度补偿电路，配置为依据当前的数字电压信号及温度补偿表获取第一控制字；
    所述非线性补偿电路，配置为依据当前的AFC控制字及非线性补偿表获取第二控制字；
    所述调谐电路，配置为依据所述第一控制字及第二控制字对电容阵列进行调节，以实现调谐所述晶体振荡器电路的频率。
  8. 根据权利要求7所述晶体振荡器电路，其中，所述当前的数字电压信号由输入的模拟电压信号转换得到，且与温度相关；
    相应的，所述晶体振荡器电路还包括模数转换器，配置为将输入的模拟电压信号转换得到对应的数字电压信号。
  9. 根据权利要求7或8所述晶体振荡器电路，其中，所述晶体振荡器电路还包括处理器，配置为确定晶体的温度系数，并依据确定的温度系数获取对应所述晶体的温度补偿表。
  10. 根据权利要求7或8所述晶体振荡器电路，其中，所述温度补偿电路，配置为依据当前的数字电压信号确定对应的温度值，并依据所述温度值采用查找表的方式获取温度补偿表中对应所述温度值的第一补偿电容，依据所述第一补偿电容产生第一控制字。
  11. 根据权利要求10所述晶体振荡器电路，其中，所述非线性补偿电路，配置为依据当前的AFC控制字采用查找表的方式获取非线性补偿表中对应所述AFC控制字的第二补偿电容，依据所述第二补偿电容产生第二控制字。
  12. 根据权利要求8所述晶体振荡器电路，其中，所述调谐电路，配置为将所述第一控制字及第二控制字相加获得第三控制字，依据所述第三控制字调节电容阵列的大小，以实现调谐所述晶体振荡器电路的频率。
  13. 一种计算机存储介质，所述计算机存储介质中存储有计算机可执行指令，该计算机可执行指令用于执行权利要求1至6任一项所述的晶体振荡器电路的调谐方法。
PCT/CN2016/073540 2015-06-26 2016-02-04 晶体振荡器电路、晶体振荡器电路的调谐方法及存储介质 WO2016206384A1 (zh)

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