CN111835286B - Crystal static capacitance offset circuit - Google Patents
Crystal static capacitance offset circuit Download PDFInfo
- Publication number
- CN111835286B CN111835286B CN202010734479.7A CN202010734479A CN111835286B CN 111835286 B CN111835286 B CN 111835286B CN 202010734479 A CN202010734479 A CN 202010734479A CN 111835286 B CN111835286 B CN 111835286B
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- crystal
- static capacitance
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- module
- resistor
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- 239000013078 crystal Substances 0.000 title claims abstract description 96
- 230000003068 static effect Effects 0.000 title claims abstract description 53
- 230000010355 oscillation Effects 0.000 claims abstract description 31
- 230000000903 blocking effect Effects 0.000 claims abstract description 23
- 238000002955 isolation Methods 0.000 claims abstract description 8
- 239000003990 capacitor Substances 0.000 claims description 27
- 238000010586 diagram Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/02—Details
- H03B5/04—Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
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- Oscillators With Electromechanical Resonators (AREA)
Abstract
The invention is applicable to the technical field of crystal oscillators, and provides a crystal static capacitance cancellation circuit, which comprises: the static capacitance offset module comprises a blocking unit; the blocking module is suitable for being connected with the first end of the crystal and is also connected with the counteracting module and used for carrying out direct current isolation with other circuits inside a crystal oscillation chip of the crystal oscillator; the static capacitance offset module is used for increasing the negative resistance of the oscillating circuit, wherein the blocking unit is suitable for being connected with the second end of the crystal and used for carrying out direct current isolation with other circuits inside the crystal oscillating chip. The invention can increase the negative resistance of the crystal oscillation chip circuit by debugging the resistance and the capacitance in the static capacitance offset module, so that the crystal oscillator can maintain stable and reliable oscillation.
Description
Technical Field
The invention belongs to the technical field of crystal oscillators, and particularly relates to a crystal static capacitance cancellation circuit.
Background
The crystal oscillator has the characteristics of high frequency stability and low phase noise, can be used as a reference signal source of various systems, and is widely applied to electronic systems of military and civil products. The crystal oscillator comprises a crystal resonator and a crystal oscillation chip, wherein a crystal static capacitor C0 is an equivalent parameter for expressing parasitic capacitance of the crystal resonator, and the existence of the crystal static capacitor C can reduce the negative resistance of a crystal oscillation chip circuit to a certain extent, reduce the oscillation margin of the crystal oscillator and possibly cause unstable oscillation and even stop oscillation.
In the prior art, the influence of the crystal static capacitance on the negative resistance of the crystal oscillation chip is reduced by improving the crystal process design and strictly controlling the size of the crystal static capacitance, but the influence of the method on the negative resistance of the crystal oscillation chip circuit is limited, and the cost of crystal production is increased.
Disclosure of Invention
In view of this, the invention provides a crystal static capacitance cancellation circuit, which can reduce the influence of the crystal static capacitance on the negative resistance of the crystal oscillation chip, effectively improve the negative resistance of the crystal oscillation chip circuit and maintain the reliable oscillation of the crystal oscillator.
The embodiment of the application provides a crystal static capacitance cancellation circuit, which comprises: the static capacitance offset module comprises a blocking unit;
the blocking module is suitable for being connected with the first end of the crystal, is also connected with the static capacitance counteracting module and is used for carrying out direct current isolation with other circuits inside a crystal oscillation chip of the crystal oscillator;
the static capacitance offset module is used for increasing the negative resistance of the oscillating circuit, wherein the blocking unit is suitable for being connected with the second end of the crystal and used for carrying out direct current isolation with other circuits inside the crystal oscillating chip.
Optionally, the blocking module includes: a first capacitor;
the first end of the first capacitor is connected with the first end of the crystal, and the second end of the first capacitor is connected with the static capacitor counteracting module.
Optionally, the static capacitance cancellation module includes: the DC blocking unit comprises a first resistor, a second capacitor and an inverting amplifier, wherein the second capacitor forms the DC blocking unit.
Optionally, the first end of the first resistor is connected with the blocking module, and the second end of the first resistor is connected with the first end of the inverting amplifier and is also connected with the first end of the second resistor.
Optionally, a second end of the second resistor is connected to a second end of the inverting amplifier.
Optionally, the second end of the second resistor and the second end of the inverting amplifier are further connected to the first end of the second capacitor.
Optionally, the frequency of the oscillating circuit is less than or equal to a preset frequency.
Optionally, the preset is 150MHz.
Optionally, the first capacitance is less than or equal to 5pF, the second capacitance is less than or equal to 5pF, the first resistance is less than or equal to 1kΩ, and the second resistance is less than or equal to 1kΩ.
Optionally, the inverting amplifier is formed of a CMOS device.
Compared with the prior art, the invention has the beneficial effects that: the invention can increase the negative resistance of the crystal oscillation chip circuit by debugging the resistance and the capacitance in the static capacitance offset module, so that the crystal oscillator can maintain stable and reliable oscillation.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a crystal oscillator according to an embodiment of the present invention;
FIG. 2 is an equivalent circuit diagram of a crystal provided by an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a crystal static capacitance cancellation circuit according to an embodiment of the present invention;
fig. 4 is a circuit diagram of a crystal static capacitance cancellation circuit according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the following description will be made by way of specific embodiments with reference to the accompanying drawings.
Exemplary, FIG. 1 is an overall circuit of a crystal oscillator, R f Providing bias for the inverter to operate in the linear region to have a larger gain;together with stray capacitance, form the load of the crystal oscillator, while together with the inverter they can be equivalently negative resistance, providing the crystal with the energy it consumes, maintaining the crystalOscillating of the bulk oscillator; r is R 1 And plays a role in limiting the driving energy of the crystal oscillator so as to prevent the crystal oscillator from being damaged or abnormal.
Exemplary, FIG. 2 is an equivalent circuit diagram of a crystal, where C 0 R is crystal static capacitance ES Is the equivalent series resistance of the crystal, the value of which represents the loss of the crystal; c (C) 1 And L 1 The equivalent series capacitance and inductance of the crystal respectively.
In general, the negative resistance of the crystal oscillating circuit itself is in the order of kΩ, but after connection to the crystal, due to the static capacitance C across the crystal 0 The negative resistance of the oscillating circuit is greatly deteriorated, and the static capacitance C 0 The higher the degradation, the more pronounced is the case of an oscillating circuit at a typical frequency of 80MHz, the more negative the oscillating circuit itself has a resistance of 1.44kΩ, if the crystal static capacitance C 0 If the value of (2.0 pF) is 2.0pF, the negative resistance of the oscillating circuit will be greatly deteriorated to 179 Ω after the crystal is connected, and if the negative resistance is too low, the risk of the oscillation stop of the crystal oscillator is easily caused under the condition of changing the external environment.
Based on this, please refer to fig. 3 and fig. 4 together, an embodiment of the present application provides a crystal static capacitance cancellation circuit, which includes: a blocking module 100 and a static capacitance cancellation module 200, wherein the static capacitance cancellation module comprises a blocking unit 201;
the blocking module 100 is adapted to be connected to a first end of a crystal, and is further connected to the static capacitance cancellation module 200, and is configured to perform dc isolation with other circuits inside a crystal oscillation chip of a crystal oscillator;
the static capacitance cancellation module 200 is configured to increase a negative resistance of an oscillating circuit, where the blocking unit 201 is adapted to be connected to the second end of the crystal and configured to perform dc isolation with other circuits inside the crystal oscillating chip.
Optionally, the blocking module 100 includes: first capacitor C 1 ；
The first capacitor C 1 Is connected with the first end of the crystal, the first capacitor C 1 And the static capacitanceThe counteracting module is connected.
Optionally, the static capacitance cancellation module 200 includes: first resistor R 1 A second resistor R 2 Second capacitor C 2 And an inverting amplifier AMP, wherein the second capacitor C 2 The blocking unit 201 is constituted.
For the first resistor R 1 A second capacitor C 2 By debugging, the negative resistance of the oscillating circuit can be increased. Specifically, according to the design requirement of reaching a specific negative resistance value at a specific frequency, the crystal static capacitance cancellation circuit provided by the invention is subjected to negative resistance-frequency characteristic simulation, and a first resistor R is subjected to 1 A second capacitor C 2 Adjust the first resistance R 1 A second capacitor C 2 May increase or decrease.
The effect of crystal static capacitance in the circuit is the same as that in the overall circuit of the crystal oscillator shown in fig. 1And the same as the load of the crystal oscillation circuit. The crystal static capacitance offset circuit provided by the application is reversely connected in parallel at two ends of the crystal oscillation circuit, and extracts part of crystal static capacitance as self load, which is equivalent to offset the influence of part of crystal static capacitance.
Optionally, the first resistor R 1 Is connected to the blocking module 100, the first resistor R 1 Is connected to the first end of the inverting amplifier AMP and is also connected to the second resistor R 2 Is connected to the first end of the housing.
Optionally, the second resistor R 2 Is connected to the second terminal of the inverting amplifier AMP.
Optionally, the second resistor R 2 And the second terminal of the inverting amplifier AMP is also connected to the second capacitor C 2 Is connected to the first end of the housing.
Optionally, the frequency of the oscillating circuit is less than or equal to a preset frequency.
Optionally, the preset is 150MHz.
Optionally, the first capacitor C 1 Less than or equal to 5pF, the second capacitor C 2 Less than or equal to 5pF, the first resistor R 1 And the second resistance is less than or equal to 1k omega and less than or equal to 1k omega.
Optionally, the inverting amplifier AMP is formed of a CMOS device.
The static capacitance offset circuit of the crystal oscillator can be integrated into the oscillation chip by adopting the COMS chip technology, the occupied area is about 2% of the oscillation circuit chip, and the increase of the chip cost is almost negligible, so that the static capacitance offset circuit of the crystal oscillator can be directly integrated in the crystal oscillation chip, the influence of the static capacitance on the negative resistance of the oscillation circuit is effectively avoided, the stable and reliable oscillation of the crystal oscillator is realized, and the cost of the oscillation chip is not increased.
By adopting the crystal static capacitance offset circuit provided by the application, the negative resistance of the oscillating circuit deteriorated to 179 omega in the above example can be increased to 431 omega, so that the oscillation margin is effectively increased, and the crystal oscillator can maintain stable and reliable oscillation.
Compared with the prior art, the invention has the beneficial effects that: the invention can increase the negative resistance of the crystal oscillation chip circuit by debugging the resistance and the capacitance in the static capacitance offset module, so that the crystal oscillator can maintain stable and reliable oscillation.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (5)
1. A crystal static capacitance cancellation circuit, comprising: the static capacitance offset module comprises a blocking unit;
the blocking module is suitable for being connected with the first end of the crystal, is also connected with the static capacitance counteracting module and is used for carrying out direct current isolation with other circuits inside a crystal oscillation chip of the crystal oscillator;
the static capacitance counteracting module is used for increasing the negative resistance of the oscillating circuit, wherein the blocking unit is suitable for being connected with the second end of the crystal and used for carrying out direct current isolation with other circuits in the crystal oscillating chip;
the blocking module includes: a first capacitor;
the first end of the first capacitor is connected with the first end of the crystal, and the second end of the first capacitor is connected with the static capacitor counteracting module;
the static capacitance cancellation module includes: the first resistor, the second capacitor and the inverting amplifier, wherein the second capacitor forms the blocking unit;
the first end of the first resistor is connected with the blocking module, and the second end of the first resistor is connected with the first end of the reverse amplifier and also connected with the first end of the second resistor;
the second end of the second resistor is connected with the second end of the reverse amplifier;
the second end of the second resistor and the second end of the inverting amplifier are also connected with the first end of the second capacitor.
2. The crystal static capacitance cancellation circuit according to claim 1, wherein the frequency of the oscillating circuit is equal to or less than a preset frequency.
3. The crystal static capacitance cancellation circuit according to claim 2, wherein said predetermined frequency is 150MHz.
4. The crystal static capacitance cancellation circuit according to claim 1, wherein the first capacitance is equal to or less than 5pF, the second capacitance is equal to or less than 5pF, the first resistance is equal to or less than 1kΩ, and the second resistance is equal to or less than 1kΩ.
5. The crystal static capacitance cancellation circuit according to claim 1, wherein said inverting amplifier is constituted by a CMOS device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010734479.7A CN111835286B (en) | 2020-07-27 | 2020-07-27 | Crystal static capacitance offset circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010734479.7A CN111835286B (en) | 2020-07-27 | 2020-07-27 | Crystal static capacitance offset circuit |
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| Publication Number | Publication Date |
|---|---|
| CN111835286A CN111835286A (en) | 2020-10-27 |
| CN111835286B true CN111835286B (en) | 2024-02-02 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010734479.7A Active CN111835286B (en) | 2020-07-27 | 2020-07-27 | Crystal static capacitance offset circuit |
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| CN (1) | CN111835286B (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61118002A (en) * | 1984-11-14 | 1986-06-05 | Matsushita Electric Works Ltd | Crystal oscillation circuit |
| US6624708B1 (en) * | 2002-06-25 | 2003-09-23 | Sandia Corporation | Active shunt capacitance cancelling oscillator circuit |
| CN1812252A (en) * | 2005-01-27 | 2006-08-02 | 松下电器产业株式会社 | Voltage-controlled oscillator |
| JP2007208490A (en) * | 2006-01-31 | 2007-08-16 | Nippon Dempa Kogyo Co Ltd | Crystal oscillator |
| US7352255B1 (en) * | 2003-12-23 | 2008-04-01 | Cypress Semiconductor Corporation | Circuit, system, and method for fine tuning crystal frequency accuracy |
| CN103973225A (en) * | 2014-05-21 | 2014-08-06 | 北京遥测技术研究所 | High-impedance crystal resonator serial oscillating circuit and commissioning method thereof |
| CN105871369A (en) * | 2015-10-23 | 2016-08-17 | 华南理工大学 | Crystal oscillator rapid oscillation-starting method |
| CN110440883A (en) * | 2019-07-19 | 2019-11-12 | 广州大学 | A kind of the direct capacitance compensation circuit and method of quartz crystal microbalance |
-
2020
- 2020-07-27 CN CN202010734479.7A patent/CN111835286B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61118002A (en) * | 1984-11-14 | 1986-06-05 | Matsushita Electric Works Ltd | Crystal oscillation circuit |
| US6624708B1 (en) * | 2002-06-25 | 2003-09-23 | Sandia Corporation | Active shunt capacitance cancelling oscillator circuit |
| US7352255B1 (en) * | 2003-12-23 | 2008-04-01 | Cypress Semiconductor Corporation | Circuit, system, and method for fine tuning crystal frequency accuracy |
| CN1812252A (en) * | 2005-01-27 | 2006-08-02 | 松下电器产业株式会社 | Voltage-controlled oscillator |
| JP2007208490A (en) * | 2006-01-31 | 2007-08-16 | Nippon Dempa Kogyo Co Ltd | Crystal oscillator |
| CN103973225A (en) * | 2014-05-21 | 2014-08-06 | 北京遥测技术研究所 | High-impedance crystal resonator serial oscillating circuit and commissioning method thereof |
| CN105871369A (en) * | 2015-10-23 | 2016-08-17 | 华南理工大学 | Crystal oscillator rapid oscillation-starting method |
| CN110440883A (en) * | 2019-07-19 | 2019-11-12 | 广州大学 | A kind of the direct capacitance compensation circuit and method of quartz crystal microbalance |
Non-Patent Citations (3)
| Title |
|---|
| "120MHz低相噪恒温晶体振荡器的研究";王占奎;《中国优秀硕士学位论文全文数据库•信息科技辑》;第2010年卷(第1期);第1-74页 * |
| "Improving the Short-Circuit Reliability in IGBTs: How to Mitigate Oscillations";Paula Diaz Reigosa等;Paula Diaz Reigosa等，《IEEE Transactions on Power Electronics》;第33卷(第7期);第5603-5612页 * |
| "一种20MHz低相噪晶体振荡器的设计";钱丰;《中国优秀硕士学位论文全文数据库•信息科技辑》;第2011年卷(第9期);第1-71页 * |
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| CN111835286A (en) | 2020-10-27 |
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