RC relaxation oscillator with temperature compensation and based on voltage control variable capacitance

Abstract

The invention provides an RC relaxation oscillator with temperature compensation and based on a voltage-controlled variable capacitor, and the oscillator comprises a main chip which comprises an RC relaxation oscillator and is used for generating a clock signal; the control module is used for collecting the temperature of the main body chip, obtaining a temperature sampling value, outputting an analog voltage according to the temperature sampling value, and coupling the analog voltage to the first end of the variable capacitor. The variable capacitor with temperature compensation and based on voltage control is adopted, the precision of frequency compensation can be improved to 0.1 Hz or lower, it is achieved that a quartz crystal oscillator is replaced by an all-silicon chip, expensive MEMS process devices are not needed, and cost is reduced; according to the variable capacitor structure with the temperature compensation function, the temperature drift value and the frequency precision index level are improved through temperature compensation, working is stable, meanwhile, the variable capacitor structure with the temperature compensation function can be suitable for any RC relaxation oscillator, the matching degree is high, and therefore large-scale mass production can be achieved on the premise that the product yield is guaranteed.

Description

RC Relaxation Oscillator Based on Voltage-Controlled Variable Capacitor with Temperature Compensation Technical Field

[0001] The present disclosure relates to the technical field of electronic circuits, and in particular to an RC relaxation oscillator with temperature compensation and based on a voltage-controlled variable capacitor. Background Art

[0002] An RC circuit, or resistor-capacitance circuit, is a circuit consisting of a resistor (R) and a capacitor (C) in analog and digital circuits. Traditional RC-based relaxation oscillators are widely used in clock designs with low precision requirements, such as those for microcontroller units (MCUs). However, these oscillators typically exhibit a temperature drift of approximately 1000 ppm / °C within the -55°C to 125°C range.

[0003] Although technicians in this field can increase the temperature drift value to around 10-100ppm / °C through digital circuit adjustment and temperature correction, some fundamental defects still exist: first, it is impossible to balance product yield and large-scale stable mass production; second, the temperature drift coefficient is still too high to replace quartz crystal oscillators; third, since the influence of parasitic resistance / capacitance under high precision cannot be eliminated, it is difficult to effectively provide sufficient initial accuracy, such as 100ppm.

[0004] Summary of the Invention

[0005] To address the aforementioned technical issues, the present disclosure provides a temperature-compensated RC relaxation oscillator based on a voltage-controlled variable capacitor. To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is provided below. This summary is not intended to be a comprehensive review, identify key or important components, or delineate the scope of protection for these embodiments. Its sole purpose is to present some concepts in a simplified form, serving as a prelude to the detailed description that follows.

[0006] This disclosure adopts the following technical solutions:

[0007] The present disclosure provides a temperature-compensated RC relaxation oscillator based on a voltage-controlled variable capacitor, comprising:

[0008] A main chip includes an RC relaxation oscillator for generating a clock signal, wherein the RC relaxation oscillator includes a variable capacitor, a bias current source, a comparator, and a resistor;

[0009] The control module is used to collect the temperature of the main chip, obtain a temperature sampling value, and output an analog voltage according to the temperature sampling value and couple it to the first end of the variable capacitor.

[0010] Furthermore, the main chip includes at least one variable capacitor.

[0011] Furthermore, the control module includes: a temperature sensor; the temperature sensor is used to collect the temperature of the main chip and output the temperature sampling value.

[0012] Furthermore, the control module also includes: a digital signal processor; the digital signal processor is coupled to the variable capacitor and the temperature sensor, and is used to receive the temperature sampling value and perform calculations to obtain and output the voltage of the variable capacitor corresponding to the temperature.

[0013] Furthermore, the control module also includes: an analog-to-digital converter; the analog-to-digital converter is coupled to the temperature sensor and the digital signal processor, and the analog-to-digital converter receives the temperature sampling value and converts the temperature sampling value into a digital voltage signal and then transmits it to the digital signal processor.

[0014] In which, the control module also includes: a digital-to-analog converter; the digital-to-analog converter is coupled to the digital signal processor and the first end of the variable capacitor, and the digital-to-analog converter converts the voltage output by the digital signal processor into an analog voltage signal and applies it to the first end of the variable capacitor.

[0015] Among them, the control module also includes: a voltage control generator; the voltage control generator includes: an adder and / or a multiplier; the temperature sampling value output by the temperature sensor is processed by the voltage control generator to output an analog voltage signal, and applied to the first end of the variable capacitor.

[0016] Furthermore, the data input terminal of the digital signal processor is connected to the output terminal of the main chip, and the digital signal processor also inputs a reference clock signal provided by an external clock source.

[0017] Furthermore, the variable capacitor is a metal oxide semiconductor field effect transistor MOSFET capacitor or a variable capacitance Varactor capacitor.

[0018] Furthermore, the bias current source outputs two groups of current sources, wherein the output end of the first group of current sources is coupled to the first end of the resistor, and the output end of the second group of current sources is coupled to the second end of the variable capacitor; the first end of the resistor is also coupled to the first input end of the comparator, and the second end of the resistor is grounded, thereby generating a reference voltage at the first input end of the comparator; the second input end of the comparator is coupled to the second end of the variable capacitor.

[0019] Furthermore, the main chip further includes: a logic controller, and the logic controller is connected to the output end of the comparator.

[0020] The beneficial effects brought about by this disclosure are:

[0021] 1. This disclosure uses a voltage-controlled variable capacitor with temperature compensation to improve frequency compensation accuracy to 0.1 Hz or lower, making it possible to replace quartz crystal oscillators with all-silicon chips. It also eliminates the need for expensive MEMS (Micro-Electro-Mechanical System) process components, reducing costs.

[0022] 2. Temperature drift value and frequency accuracy are exponentially improved through temperature compensation, and the operation is stable. At the same time, the variable capacitor structure with temperature compensation disclosed in the present invention can be applied to any RC relaxation oscillator with high matching degree, so large-scale mass production can be achieved while ensuring product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] FIG1 is a schematic structural diagram of an RC relaxation oscillator according to an embodiment of the present disclosure.

[0025] FIG2 is a schematic structural diagram of an RC relaxation oscillator with two variable capacitors according to the present disclosure.

[0026] FIG3 is a schematic structural diagram of an RC relaxation oscillator with two variable capacitors according to the present disclosure.

[0027] FIG4 is a schematic structural diagram of an RC relaxation oscillator with two variable capacitors combined with a non-variable capacitor according to the present disclosure. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the embodiments described are only a portion of the embodiments of the present disclosure, and not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by persons of ordinary skill in the art without creative effort are within the scope of protection of the present disclosure.

[0029] As shown in Figures 1-4, in some illustrative embodiments, the present disclosure provides a voltage-controlled variable capacitor (VCVC)-based RC relaxation oscillator with temperature compensation, including a main chip 1 and a control module 4. The main chip 1 includes circuitry that implements the oscillator and generates a clock signal. The control module 4 is configured to control the main chip 1 using a temperature compensation algorithm to compensate for frequency drift of the clock signal caused by temperature variations.

[0030] As shown in Figure 1, the main chip 1, used to generate the clock signal, includes a bias current source Ibias, a comparator Cmp, a resistor Rosc, and a variable capacitor Cosc. The variable capacitor Cosc can be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) capacitor, a varactor capacitor, or any other voltage-controlled variable capacitor under any process conditions, thus providing more possibilities for production process selection.

[0031] Exemplarily, the main chip 1 uses at least one variable capacitor. As shown in Figures 2-4, there are structural diagrams of the RC relaxation oscillator when two variable capacitors are used. In this case, the two variable capacitors are respectively recorded as the first variable capacitor Cosc1 and the second variable capacitor Cosc2, and the corresponding comparators are respectively recorded as the first comparator Cmp1 and the second comparator Cmp2. The introduction of dual-channel or multi-channel voltage-controlled variable capacitors can achieve more functions and higher-precision multi-dimensional RC relaxation oscillator usage scenarios. Moreover, the dual-channel or multi-channel voltage-controlled variable capacitor structure can be controlled completely independently or in a variety of combinations according to actual usage requirements.

[0032] For example, as shown in FIG1 , the bias current source Ibias outputs two sets of current sources, denoted as a first current source Iref and a second current source Ia. The first current source Iref generates a reference voltage Vref for the comparator Cmp across the resistor Rosc. The second current source Ia charges the variable capacitor Cosc.

[0033] Exemplarily, as shown in FIG2-4 , when two variable capacitors are used, the second current source Ia is further divided into a current source Ia1 and a current source Ia2 to charge the variable capacitors of each channel.

[0034] Exemplarily, the main chip 1 may further include: a logic controller 2, which is connected to the output ends of the first comparator Cmp1 and the second comparator Cmp2. The use of the logic controller 2 can reduce the delay of the comparator and the effects of the RC relaxation oscillator current, capacitance, and comparator input offset.

[0035] The control module 4 included in the RC relaxation oscillator of VCVC is used to collect the temperature of the main chip 1, obtain the temperature sampling value, and output the analog voltage signal V according to the temperature sampling value. DAC Applied to the variable capacitor Cosc.

[0036] In some examples, the control module 4 may include: a temperature sensor 3 , a digital signal processor DSP (Digital Signal Processor), an analog-to-digital converter ADC (Analog-to-Digital Converter), and a digital-to-analog converter DAC (Digital-to-Analog Converter).

[0037] For example, as shown in FIG3 and FIG4, for the case of two variable capacitors, two digital-to-analog converters can be provided, which are respectively recorded as a first digital-to-analog converter DAC1 and a second digital-to-analog converter DAC2, respectively generating a first analog voltage signal V DAC1 and the second analog voltage signal V DAC2 .

[0038] The temperature sensor 3 is used to collect the temperature of the main chip 1 and transmit the temperature sample value directly to the digital signal processor DSP. In some examples, the temperature sample value can be a digital value. The digital signal processor DSP can obtain the temperature sample value collected by the temperature sensor 3 and calculate it using a temperature compensation algorithm to obtain a digital voltage value, such as a binary value, required to control the variable capacitor.

[0039] Furthermore, in some examples, the temperature sampled value can be an analog value. The temperature sensor 3 samples the temperature of the main chip 1, converts it into a digital voltage signal via the analog-to-digital converter (ADC), and then uploads it to the digital signal processor (DSP). The digital-to-analog converter (DAC) converts the digital voltage value output by the digital signal processor DSP into an analog voltage signal and applies it to the variable capacitor Cosc. The data input terminal of the digital signal processor DSP is connected to the output terminal of the main chip 1, and simultaneously obtains the reference clock signal REF_CLK provided by an external clock source.

[0040] In this embodiment, the RC relaxation oscillator uses the temperature sensor 3 to sample the temperature of the main chip 1, and then converts it into a digital value through the analog-to-digital converter ADC; the digital signal processor DSP calculates the voltage digital value of the variable capacitor Cosc corresponding to the current temperature based on a specific temperature compensation algorithm, wherein the temperature compensation algorithm can be any existing compensation algorithm, which will not be described in detail in this article; the digital-to-analog converter DAC converts the analog voltage signal V required for frequency stabilization DAC The capacitance value corresponding to the current temperature is applied to the variable capacitor Cosc to compensate for the frequency drift caused by temperature changes. This method allows the frequency of the RC relaxation oscillator's output terminal, OSCOUT, to achieve an initial accuracy of 10ppm. Furthermore, the frequency temperature drift of the output terminal, OSCOUT, can be less than 100ppm within the -55°C to 125°C range, for example, approximately 0.1-1ppm / °C.

[0041] The analog voltage signal V that controls the variable capacitor Cosc DAC The present invention is not limited to providing various precision digital-to-analog converters DAC. In one example, the digital-to-analog converter ADC, digital signal processor DSP and digital-to-analog converter DAC can be replaced by a voltage control generator. The voltage control generator can include other forms of voltage control generators such as adders and multipliers. The temperature sample value output by the temperature sensor 3 is processed by the voltage control generator to output an analog voltage signal V DAC , and applied to the variable capacitor Cosc, that is, according to the temperature compensation requirements, the temperature sampling value generated by the temperature sensor 3 is passed through various adders and multipliers to generate an analog voltage signal V DAC , expanding the application scenarios of RC relaxation oscillators based on voltage-controlled variable capacitors with temperature compensation.

[0042] The disclosed temperature-compensated voltage-controlled variable capacitor can improve frequency compensation accuracy to 0.1 Hz or lower, making it practical to replace quartz crystal oscillators with all-silicon chips without the need for expensive MEMS process devices. Furthermore, any RC relaxation oscillator can incorporate the voltage-controlled variable capacitor architecture to achieve exponential improvements in temperature drift and frequency accuracy. Furthermore, a digital signal processor (DSP) can be combined with a voltage-controlled variable capacitor RC relaxation oscillator based on any temperature compensation algorithm to achieve even better temperature compensation.

[0043] As shown in Figure 4, the logic control and circuit architecture of an RC relaxation oscillator that reduces comparator delay and offset is shown. Multiple voltage-controlled variable capacitors, along with non-variable capacitors C1, C2, or capacitor arrays, are introduced to achieve more functional and higher-precision multi-dimensional RC relaxation oscillator usage scenarios. Furthermore, multiple voltage-controlled variable and non-variable capacitors and capacitor arrays can be controlled independently or in various combinations as needed. The voltage control generator can be a digital-to-analog converter, a multiplier, an adder, or other form of voltage control generator.

[0044] The above description is merely a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A temperature-compensated resistor-capacitor RC relaxation oscillator based on a voltage-controlled variable capacitor, characterized in that: include: A main chip, including an RC relaxation oscillator for generating a clock signal, wherein the RC relaxation oscillator includes a variable capacitor, a bias current source, a comparator, and a resistor; The control module is used to collect the temperature of the main chip, obtain a temperature sampling value, and output an analog voltage according to the temperature sampling value and couple it to the first end of the variable capacitor.

2. The temperature-compensated RC relaxation oscillator based on voltage-controlled variable capacitance according to claim 1, characterized in that: The main chip includes at least one variable capacitor.

3. The temperature-compensated RC relaxation oscillator based on voltage-controlled variable capacitance according to claim 1 or 2, characterized in that: The control module includes: a temperature sensor; The temperature sensor is used to collect the temperature of the main chip and output the temperature sampling value.

4. The temperature-compensated RC relaxation oscillator based on voltage-controlled variable capacitance according to claim 3, characterized in that: The control module also includes: a digital signal processor; The digital signal processor is coupled to the variable capacitor and the temperature sensor, and is used to receive the temperature sampling value and perform calculations to obtain and output the voltage of the variable capacitor corresponding to the temperature.

5. The temperature-compensated RC relaxation oscillator based on voltage-controlled variable capacitance according to claim 4, characterized in that: The control module also includes: an analog-to-digital converter; the analog-to-digital converter is coupled to the temperature sensor and the digital signal processor, and the analog-to-digital converter receives the temperature sampling value and converts the temperature sampling value into a digital voltage signal and then transmits it to the digital signal processor.

6. The temperature-compensated RC relaxation oscillator based on voltage-controlled variable capacitance according to claim 4 or 5, characterized in that: The control module also includes: a digital-to-analog converter; the digital-to-analog converter is coupled to the digital signal processor and the first end of the variable capacitor, and the digital-to-analog converter converts the voltage output by the digital signal processor into an analog voltage signal and applies it to the first end of the variable capacitor.

7. The temperature-compensated RC relaxation oscillator based on voltage-controlled variable capacitance according to claim 3, characterized in that: The control module also includes: a voltage control generator; the voltage control generator includes: an adder and / or a multiplier; the temperature sampling value output by the temperature sensor is processed by the voltage control generator to output an analog voltage signal, which is applied to the first end of the variable capacitor.

8. The RC relaxation oscillator based on voltage-controlled variable capacitance with temperature compensation according to any one of claims 4 to 6, characterized in that: The data input terminal of the digital signal processor is connected to the output terminal of the main chip, and the digital signal processor also inputs a reference clock signal provided by an external clock source.

9. The RC relaxation oscillator based on voltage-controlled variable capacitance with temperature compensation according to any one of claims 1 to 8, characterized in that: The variable capacitor is a metal oxide semiconductor field effect transistor MOSFET capacitor or a variable capacitance Varactor capacitor.

10. The RC relaxation oscillator based on voltage-controlled variable capacitance with temperature compensation according to any one of claims 1 to 9, characterized in that: The bias current source outputs two groups of current sources, wherein the output end of the first group of current sources is coupled to the first end of the resistor, and the output end of the second group of current sources is coupled to the second end of the variable capacitor; The first end of the resistor is also coupled to the first input end of the comparator, and the second end of the resistor is grounded, so as to generate a reference voltage at the first input end of the comparator; The second input terminal of the comparator is coupled to the second terminal of the variable capacitor.

11. The temperature-compensated voltage-controlled variable capacitance resistor-capacitor RC relaxation oscillator according to claim 10, characterized in that: The main chip further includes: a logic controller, and the logic controller is connected to the output end of the comparator.

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