CN114531114A - Temperature compensation real-time clock circuit and integrated circuit - Google Patents
Temperature compensation real-time clock circuit and integrated circuit Download PDFInfo
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- CN114531114A CN114531114A CN202210127953.9A CN202210127953A CN114531114A CN 114531114 A CN114531114 A CN 114531114A CN 202210127953 A CN202210127953 A CN 202210127953A CN 114531114 A CN114531114 A CN 114531114A
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- time clock
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- 239000003990 capacitor Substances 0.000 claims abstract description 32
- 238000006243 chemical reaction Methods 0.000 claims abstract description 25
- 230000010355 oscillation Effects 0.000 claims abstract description 14
- 239000013078 crystal Substances 0.000 claims description 7
- 238000003491 array Methods 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000005669 field effect Effects 0.000 description 4
- 238000012935 Averaging Methods 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000011897 real-time detection Methods 0.000 description 1
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- 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
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- 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
- H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
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- Oscillators With Electromechanical Resonators (AREA)
Abstract
A temperature compensation real-time clock circuit comprises an oscillation circuit, a temperature sensor circuit, an analog-to-digital conversion circuit, a memory circuit, an interpolation operation circuit and a power supply selection controller. The oscillation circuit comprises a variable capacitor array, the variable capacitor array is provided with L capacitance value outputs which can be set, the output of the temperature sensor circuit is connected to the input end of the analog-digital conversion circuit, the first output end of the output of the analog-digital conversion circuit is connected to the input end of the memory circuit, the second output end of the output of the analog-digital conversion circuit is connected to the interpolation operation circuit, the memory circuit is connected to the interpolation operation circuit, the output end of the interpolation operation circuit is connected to the input end of the oscillation circuit, and the interpolation operation circuit obtains the required variable capacitor setting data for the temperature compensation of the real-time clock circuit through interpolation operation according to the obtained temperature digital quantity value and the variable capacitor setting data stored in the memory circuit.
Description
Technical Field
The invention relates to the technical field of clock integrated circuits, in particular to a temperature compensation real-time clock chip with an interpolation algorithm.
Background
Temperature compensated crystal oscillator(TCXO, Temperature Compensation X' Tal Oscillator) is an active Oscillator that can provide a high precision frequency output over a wide Temperature range. According to the temperature compensation structure, the temperature is detected through the temperature sensor, and the capacitor array in the oscillating circuit is adjusted according to temperature data, so that the temperature compensation of the oscillating frequency is realized. The compensation structure also typically includes an on-chip non-volatile memory for storing the capacitor array data corresponding to different temperatures. Wherein the switching resolution of the capacitor array directly affects the compensation accuracy. The higher the capacitor array switching resolution, the greater the required non-volatile memory capacity. For example, the capacitance switching arrays are in L groups. The required non-volatile memory capacity is also L-bank. A common temperature compensation crystal oscillator adopts a single power supply system or adopts an extra device outside a chip to build a backup power supply system. Lack of ease of use or require additional material costs.
Disclosure of Invention
In one embodiment of the present invention, a dual power supply temperature compensation real-time clock circuit includes an oscillation circuit, a temperature sensor circuit, an analog-to-digital conversion circuit, a memory circuit, an interpolation operation circuit, and a power selection controller. The oscillation circuit comprises a variable capacitor array, the variable capacitor array is provided with L capacitance value outputs which can be set, the output of the temperature sensor circuit is connected to the input end of the analog-digital conversion circuit, the first output end of the output of the analog-digital conversion circuit is connected to the input end of the memory circuit, the second output end of the output of the analog-digital conversion circuit is connected to the interpolation operation circuit, the memory circuit is connected with the interpolation operation circuit, and the output end of the interpolation operation circuit is connected to the input end of the oscillation circuit. The power selection controller has two power input terminals VDD and VBAT, and an output terminal for supplying power VCC to the internal circuit.
The invention provides a temperature compensation real-time clock chip with an interpolation algorithm, which is connected with an external crystal oscillator, and the real-time clock chip carries out temperature compensation on the frequency of the crystal oscillator by adjusting an internal capacitor array capacitance value through an interpolation operation circuit, and the required capacity of a nonvolatile memory can be reduced to 1/N of the capacity required by the existing scheme. Meanwhile, a power selection controller is integrated in the chip. The user can select the power supply scheme by oneself, and in the dual supply scheme, when external power source VDD loses electricity, power selection controller switches to stand-by power supply VBAT through real-time detection, and the chip automatically gets into low-power consumption mode this moment, guarantees stand-by power supply's live time.
Drawings
The above and other objects, features and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings. Several embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which:
FIG. 1 is a block diagram of a temperature compensated real time clock chip with an interpolation arithmetic circuit according to one embodiment of the invention.
Fig. 2 is a block diagram of an interpolation operation circuit according to one embodiment of the present invention.
FIG. 3 is a table showing the relationship between the input and the output of an interpolation circuit according to an embodiment of the present invention.
Fig. 4 is a block diagram of an oscillation circuit according to an embodiment of the present invention.
Fig. 5 is a block diagram of a power selection controller according to one embodiment of the present invention.
Detailed Description
In view of the above-described shortcomings of the prior art, it is an object of the present invention to provide a temperature compensated real time clock chip with an interpolation algorithm. By means of interpolation algorithms, the memory capacity requirements can be reduced.
In accordance with one or more embodiments, as shown in FIG. 1. A temperature compensation real-time clock circuit comprises an oscillation circuit, a temperature sensor circuit, an analog-to-digital conversion circuit, a memory circuit, an interpolation operation circuit and a power supply selection controller.
The oscillating circuit includes a variable capacitance array having L capacitance outputs that can be set. The output of the temperature sensor circuit is connected to the input end of the analog-to-digital conversion circuit. A first output end of the output of the analog-to-digital conversion circuit is connected with an input end of the memory circuit, and a second output end of the output of the analog-to-digital conversion circuit is connected with the interpolation operation circuit. The memory circuit is connected with the interpolation arithmetic circuit. The output end of the interpolation arithmetic circuit is connected with the input end of the oscillating circuit.
The problem sensor circuit is used for detecting the environment temperature of the real-time clock circuit and obtaining the analog quantity value of the environment temperature. The analog-to-digital conversion circuit converts the temperature analog quantity value into a digital quantity value, and the memory circuit stores L/N variable capacitor array setting data corresponding to the temperature compensation data.
The interpolation arithmetic circuit comprises 2 registers and an interpolation arithmetic unit connected with the registers, and the interpolation arithmetic unit carries out linear interpolation arithmetic. The interpolation arithmetic unit comprises one or more adders for carrying out operation, 2 groups of numbers are input to carry out averaging to obtain intermediate number interpolation, and then the intermediate number interpolation is used for continuing averaging to obtain the other 2 groups of interpolation. And according to the N value, dividing the difference value of the setting data of the adjacent 2 variable capacitor arrays stored in the memory circuit into N equal parts. And the interpolation operation circuit obtains the required variable capacitance setting data for the temperature compensation of the real-time clock circuit through interpolation operation according to the obtained temperature digital quantity value and the variable capacitance setting data stored in the memory circuit. As shown in fig. 2.
The temperature compensation real-time clock circuit also comprises a power supply selection controller which is used for selecting and communicating one of the power supply circuits which are used for supplying power to the temperature compensation real-time clock circuit and at least have two paths of power supply circuits. As shown in fig. 1, the power selection controller may simultaneously connect the power supply VDD and the power supply VBAT, wherein the power supply VBAT may be used as a backup power supply. In the embodiment, the connection design of the standby power supply can greatly enhance the reliability of the temperature compensation real-time clock circuit, enhance the capability of the circuit for resisting sudden faults and ensure the robustness of the real-time clock circuit as a key device of a system core.
According to one or more embodiments, a temperature compensated real time clock chip with an interpolation algorithm includes an oscillation circuit, a temperature sensor, an analog-to-digital conversion circuit, a memory, and an interpolation adjustment circuit.
The output end of the temperature sensor is connected with the input end of the analog-to-digital conversion circuit, the output end of the analog-to-digital conversion circuit is connected with the input end of the memory, and the input end of the interpolation adjusting circuit is respectively connected with the output end of the analog-to-digital conversion circuit and the output end of the memory. The output end of the interpolation adjusting circuit is connected with the input end of the oscillating circuit. The temperature sensor converts a voltage value corresponding to the temperature into digital temperature data through an analog-to-digital conversion circuit.
As shown in fig. 4, the oscillator circuit includes a current source I1, an N-type fet M0, variable capacitor arrays C1 and C2, a feedback resistor RB, and a series resistor RF. The drain electrode of the N-type field effect transistor M0 is simultaneously connected with a current source I1 and one end of a series resistor RF, the feedback resistor RB is bridged between the grid electrode and the drain electrode of the N-type field effect transistor M0, the grid electrode of the N-type field effect transistor M0 is connected with one end X1 of an external crystal oscillator, the other end of the series resistor RF is connected with one end X2 of the external crystal oscillator, and meanwhile, the grid electrode of the N-type field effect transistor M0 and the other end of the series resistor RF are connected into a variable capacitor array.
As shown in fig. 4, the oscillation circuit includes a plurality of capacitors, i.e., a 1 st capacitor, a 2 nd capacitor, ·, an nth (n is an integer of 2 or more) capacitor, 1 st to nth switches, and a switching capacitor. Or the capacitance values of the 1 st capacitor, the 2 nd capacitor, the & cnth capacitor are C0, 2 XC 0, 2n-1 XC 0. The 1 st switch to the nth switch and the 1 st capacitor to the nth capacitor may be connected in series, respectively. The capacitance value of the switching capacitor may be C0. The switch may be connected in series with the switching capacitor.
The memory stores temperature data in association with a capacitance adjustment value of the variable capacitance circuit. The interpolation arithmetic circuit may read a 1 st capacitance adjustment value and a 2 nd capacitance adjustment value corresponding to a high-order bit of the temperature data, and perform linear interpolation on the 1 st capacitance adjustment value and the 2 nd capacitance adjustment value according to a low-order bit of the temperature data to obtain a capacitance adjustment value corresponding to the temperature data. The interpolation arithmetic processing circuit may be configured to output the 1 st capacitance control data and the 2 nd capacitance control data, which are integer data of the capacitance adjustment value, to the variable capacitance circuit in a time-division manner by switching in accordance with the fractional data of the capacitance adjustment value. Thus, the memory stores a table in which temperature data and capacitance adjustment values are associated with each other. By linearly interpolating the capacitance adjustment values, capacitance adjustment values such as the temperature resolution of the correspondence table in fig. 3 are generated. This enables temperature compensation of the oscillation frequency with high accuracy. Further, since the data amount of the table can be saved, the memory capacity of the memory can be saved. Fig. 3 is a table of input and output relationships for an interpolation arithmetic circuit using parallel buses. Wherein, ADC [9:2] is the output of the analog-to-digital conversion circuit, and the output is connected to the memory; ADC [1:0] is the output of the analog-to-digital conversion circuit, and the output is connected to the interpolation operation circuit; CAPj [12:0] is the output of the interpolation arithmetic circuit, which is connected with the oscillating circuit; cmi [12:0] is the output of the memory, which is connected to the interpolation arithmetic circuit. Here, the data transmission between the circuits can also be realized in a serial manner.
In the invention, the memory stores the capacitance array data corresponding to the original 1/N temperature data, and the N value can be selected from 2, 4, 8 and 16. The interpolation algorithm circuit in the chip fills up the capacitor array data which are not stored in the memory through a fixed interpolation algorithm according to the temperature data and the capacitor array data in the memory. By the interpolation algorithm, the frequency compensation precision is improved to N times of the original precision. The required memory capacity is only 1/N.
It should be noted that while the foregoing has described the spirit and principles of the invention with reference to several specific embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, nor is the division of aspects, which is for convenience only as the features in these aspects cannot be combined. The invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (9)
1. A temperature compensated real time clock circuit comprises an oscillation circuit, a temperature sensor circuit, an analog-to-digital conversion circuit, a memory circuit, and an interpolation operation circuit,
the oscillation circuit comprises a variable capacitor array having L capacitance value outputs which can be set,
the output of the temperature sensor circuit is connected to the input end of the analog-to-digital conversion circuit,
a first output end of the output of the analog-to-digital conversion circuit is connected with an input end of the memory circuit, a second output end of the output of the analog-to-digital conversion circuit is connected with the interpolation arithmetic circuit,
the memory circuit is connected with the interpolation arithmetic circuit,
the output end of the interpolation arithmetic circuit is connected with the input end of the oscillation circuit, wherein,
the temperature sensor circuit is used for detecting the environment temperature of the real-time clock circuit and obtaining the analog quantity value of the environment temperature,
the analog-to-digital conversion circuit converts the temperature analog quantity value into a digital quantity value,
the memory circuit stores L/N variable capacitance array setting data, the variable capacitance setting data corresponding to temperature compensation data,
and the interpolation operation circuit obtains the required variable capacitance setting data for the temperature compensation of the real-time clock circuit through interpolation operation according to the obtained temperature digital quantity value and the variable capacitance setting data stored in the memory circuit.
2. The temperature-compensated real-time clock circuit of claim 1, further comprising a power selection controller configured to select one of the at least two power supply circuits coupled to supply power to the temperature-compensated real-time clock circuit.
3. The temperature-compensated real-time clock circuit of claim 1, wherein L is a positive integer greater than 2.
4. The temperature compensated real time clock circuit of claim 1, wherein the value of N is selected from 2, 4, 8, and 16.
5. The temperature compensated real time clock circuit of claim 1, wherein the interpolation circuit comprises 2 registers, and an interpolator coupled to the registers, the interpolator employing a linear interpolation,
the register is used for storing 2 variable capacitance setting data acquired from the memory circuit, and the numerical value of the temperature digital quantity acquired from the temperature sensor circuit is between compensation temperature values corresponding to the 2 variable capacitance setting data.
6. The temperature-compensated real-time clock circuit of claim 5, wherein the difference between the adjacent 2 variable capacitor array settings stored in the memory circuit is divided by N equal parts according to the value of N.
7. The temperature-compensated real-time clock circuit of claim 1, wherein the oscillator circuit is coupled in parallel with an external crystal oscillator.
8. The temperature compensated real time clock circuit of claim 7, wherein the oscillator circuit comprises a current source I1, an N fet M0, variable capacitor arrays C1 and C2, a feedback resistor RB, and a series resistor RF.
9. A real time clock integrated circuit comprising the temperature compensated real time clock circuit of claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210127953.9A CN114531114A (en) | 2022-02-11 | 2022-02-11 | Temperature compensation real-time clock circuit and integrated circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210127953.9A CN114531114A (en) | 2022-02-11 | 2022-02-11 | Temperature compensation real-time clock circuit and integrated circuit |
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| CN114531114A true CN114531114A (en) | 2022-05-24 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202210127953.9A Withdrawn CN114531114A (en) | 2022-02-11 | 2022-02-11 | Temperature compensation real-time clock circuit and integrated circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117394791A (en) * | 2023-10-17 | 2024-01-12 | 上海锐星微电子科技有限公司 | Real-time clock circuit, integrated circuit, electronic device and design method |
-
2022
- 2022-02-11 CN CN202210127953.9A patent/CN114531114A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117394791A (en) * | 2023-10-17 | 2024-01-12 | 上海锐星微电子科技有限公司 | Real-time clock circuit, integrated circuit, electronic device and design method |
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