A temperature-compensated clock circuit based on multiple sensitization

Abstract

The application discloses a temperature compensation clock circuit based on multiple sensitization, which uses multiple sensitized signals to realize high-precision temperature sensing, and realizes a high-stable clock signal through a frequency synthesizer temperature compensation. The temperature compensation clock circuit comprises a driving circuit, a mixing circuit, a frequency division circuit, a quantization circuit, a temperature compensation circuit and a frequency synthesizer circuit. The driving circuit drives a MEMS resonator to generate signals fa and fb, the mixing circuit, the frequency division circuit and the quantization circuit process the signals fa and fb to obtain a high-precision temperature sensing signal TDCout, the temperature compensation circuit generates a temperature compensation amount TDCerror by digitally marking the TDCout signal, and the frequency synthesizer circuit receives the TDCerror to temperature compensate the signal fa and generate a high-stable signal fout. The temperature compensation clock circuit obtains a multiple-sensitized high-sensitive temperature signal through mixing, frequency division and frequency ratio operation, realizes high-resolution temperature sensing, and obtains a high-stable clock through temperature compensation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field, and particularly relates to a temperature compensation clock circuit based on multiple sensitization. BACKGROUND

[0002] The integrated temperature sensor can be widely applied to temperature compensation of a reference frequency source in the temperature compensation clock circuit, and such application requires that the temperature sensor simultaneously has characteristics of high resolution, high energy efficiency, high stability and compatibility with CMOS technology, wherein the high resolution can prevent noise of the temperature sensor from increasing jitter of the temperature compensation clock circuit, the high energy efficiency can reduce a total budget proportion of the temperature sensor to the whole temperature compensation clock circuit, the high stability ensures signal source reliability of the temperature compensation clock circuit in a long-term use process at different temperatures, and meanwhile, the designed temperature sensor is required to be compatible with the CMOS technology, so as to be conveniently integrated with other circuit modules of the temperature compensation clock circuit.

[0003] In the CMOS compatible and temperature-dependent CMOS devices in the integrated temperature sensor application, BJT transistors, MOS transistors and resistors and the like are often used in the integrated temperature sensor design, although the CMOS compatible devices have been improved for many years, the precision and resolution of the temperature sensor designed by using the CMOS compatible devices are still limited. The MEMS resonator also has good temperature-dependent characteristics, and a high-resolution and high-energy-efficiency temperature sensor can be designed based on the temperature-dependent characteristics of the MEMS resonator. According to the investigation of the intelligent temperature sensor, the MEMS resonator-based temperature sensor is the method that can achieve the highest precision and resolution of the temperature sensor at present. The resolution of the temperature sensor designed based on the MEMS resonator is several orders of magnitude higher than that of the temperature sensor designed based on the BJT and the resistor, and higher micro-Kelvin resolution can be achieved.

[0004] The resolution of the MEMS resonator-based temperature sensor is mainly determined by two factors: a temperature coefficient of the MEMS resonator and noise of a temperature conversion circuit. The higher the temperature coefficient, the higher the sensitivity of the temperature sensor to temperature change, and smaller temperature change can be sensed. The lower the noise of the temperature conversion circuit, the higher the resolution of the temperature sensor to temperature detection. In the design of the MEMS resonator-based temperature sensor, for the temperature conversion circuit using the same structure, if no special improvement is made on the noise existing in the circuit, in order to obtain a high-resolution temperature sensor, the sensitivity of the MEMS resonator for temperature sensing needs to be as high as possible. SUMMARY

[0005] The application aims to solve the problems of poor detection precision and resolution in the prior art temperature measurement methods based on BJT, MOS transistor and resistor, and provides a temperature compensation clock circuit based on multiple sensitization.

[0006] In order to achieve the above object, the present application adopts the following technical scheme: a temperature compensation clock circuit based on multiple sensitization, comprising: two MEMS driving circuits for driving MEMS resonators to generate oscillation signals fa and fb respectively;

[0007] A mixing circuit is configured to mix the received oscillation signals fa and fb to generate a difference frequency signal fb-fa;

[0008] A frequency division circuit is configured to perform N frequency division operation on the received oscillation signal fa to generate a frequency division signal fa / N;

[0009] A quantization circuit is configured to perform frequency ratio operation on the received mixing signal fb-fa and the frequency division signal fa / N to generate a temperature related signal TDCout;

[0010] A temperature compensation circuit is configured to perform digital scaling on the received temperature related signal TDCout to generate a temperature compensation TDCerror;

[0011] A frequency synthesizer circuit is configured to perform temperature compensation on the received oscillation signal fa based on the received temperature compensation TDCerror to generate a high-stability clock signal fout.

[0012] Further, the MEMS driving circuit comprises: an input stage circuit, a variable gain amplifier, an output stage circuit, and an automatic gain control circuit.

[0013] The output end of the input stage circuit is connected to the input end of the variable gain amplifier, the output end of the variable gain amplifier is connected to the input end of the output stage circuit, the output end of the output stage circuit is connected to the input end of the automatic gain control circuit, and the output end of the automatic gain control circuit is connected to the input end of the variable gain amplifier.

[0014] Further, the automatic gain control circuit comprises: a peak detector and an error amplifier.

[0015] The input end of the peak detector is connected to the output end of the output stage circuit, and the output end of the peak detector is connected to the input end of the error amplifier, and the output end of the error amplifier is connected to the input end of the variable gain amplifier.

[0016] Further, the mixing circuit comprises: a mixer and a low-pass filter.

[0017] The input end of the mixer receives the oscillation signals fa and fb generated by the MEMS driving circuit, the output end of the mixer is connected to the input end of the low-pass filter, and the output end of the low-pass filter outputs the difference frequency signal fb-fa to the quantization circuit.

[0018] Further, the frequency division circuit is an integer N frequency divider.

[0019] Further, the quantization circuit comprises a counter, a time-to-digital conversion circuit and a digital loop filter.

[0020] The input end of the counter receives a frequency division signal fa / N from a frequency division circuit, and the output end of the counter is connected to the input end of a digital loop filter, the input end of the time-to-digital conversion circuit receives a difference frequency signal fb-fa from a frequency mixing circuit, and the output end of the time-to-digital conversion circuit is also connected to the input end of the digital loop filter, and the output end of the digital loop filter outputs a temperature related signal TDCout to a temperature compensation circuit.

[0021] Further, the temperature compensation circuit is a high-order polynomial temperature compensation circuit.

[0022] Further, the frequency synthesizer circuit comprises a phase frequency detector, a charge pump, a loop filter, a voltage controlled oscillator, a multi-modulus frequency divider and a Sigma-Delta modulator.

[0023] The input ends of the Sigma-Delta modulator respectively receive an oscillation signal fa generated by a MEMS driving circuit and a temperature compensation quantity TDCerror generated by a temperature compensation circuit, and the output end of the Sigma-Delta modulator is connected to the input end of a multi-modulus frequency divider, the input end of the phase frequency detector receives the oscillation signal fa generated by the MEMS driving circuit, and the input end of the phase frequency detector is also connected to the output end of the multi-modulus frequency divider, the output end of the phase frequency detector is connected to the input end of the charge pump, the output end of the charge pump is connected to the input end of the loop filter, the output end of the loop filter is connected to the input end of the voltage controlled oscillator, the output end of the voltage controlled oscillator is connected to the input end of the multi-modulus frequency divider, and the output end of the voltage controlled oscillator is also connected to the input end of an out-of-loop frequency divider, the output end of the out-of-loop frequency divider is connected to the input end of a driver, and the output end of the driver outputs a high-stable clock signal fout.

[0024] Advantages:

[0025] 1. The temperature compensation clock circuit based on multiple sensitization provided by the application realizes the hundred-fold sensitization of the temperature signal through frequency mixing, frequency division and signal processing of frequency ratio, and completes the millikelvin level temperature sensing precision and the microkelvin level temperature resolution. The high-precision and high-resolution temperature sensing compensation crystal oscillator realizes the frequency stability of ±0.1ppm in a wide temperature range.

[0026] 2、The compensated crystal oscillator can greatly reduce the influence of environmental temperature change on oscillation frequency, thereby providing ultra-high frequency stability and accuracy, and can be widely applied to high-tech fields such as communication, navigation, measuring instrument, military industry, aerospace and power system. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a whole framework of a temperature compensation clock circuit based on multiple sensitization provided by the embodiment of the application;

[0028] Figure 2 is a module schematic diagram of a temperature compensation clock circuit based on multiple sensitization provided by the embodiment of the application;

[0029] Figure 3 is a driving circuit module schematic diagram of a temperature compensation clock circuit based on multiple sensitization provided by the embodiment of the application;

[0030] Figure 4 is a frequency ratio circuit module schematic diagram of a temperature compensation clock circuit based on multiple sensitization provided by the embodiment of the application. DETAILED DESCRIPTION

[0031] The application will be further explained below in combination with the drawings.

[0032] As shown in the drawings, Figure 1 a temperature compensation clock circuit based on multiple sensitization, comprising: two MEMS driving circuits, respectively driving MEMS resonators to generate oscillation signals fa and fb;

[0033] a mixing circuit, mixing the received oscillation signals fa and fb to generate a difference frequency signal fb-fa;

[0034] a frequency dividing circuit, performing N frequency dividing operation on the received oscillation signal fa to generate a frequency dividing signal fa / N;

[0035] a quantization circuit, performing frequency ratio operation on the received mixing signal fb-fa and the frequency dividing signal fa / N to generate a temperature related signal TDCout;

[0036] a temperature compensation circuit, performing digital scaling on the received temperature related signal TDCout to generate a temperature compensation TDCerror;

[0037] a frequency synthesizer circuit, performing temperature compensation on the received oscillation signal fa according to the received temperature compensation TDCerror to generate a high-stable clock signal fout.

[0038] In this embodiment, the frequencies of the oscillation signals fa and fb can be different values, depending on the design of the MEME resonator. In the example, the frequencies of the oscillation signals fa and fb are 48 MHz and 48.5 MHz, respectively, to verify the actual effect of the multi-sensitization-based temperature compensation clock circuit provided by the application.

[0039] As shown in Figures 2-4 The MEMS drive circuit is a cross-group amplifier, which includes an input stage circuit, a variable gain amplifier, an output stage circuit, and an automatic gain control circuit. The output end of the input stage circuit is connected to the input end of the variable gain amplifier. The output end of the variable gain amplifier is connected to the input end of the output stage circuit. The output end of the output stage circuit is connected to the input end of the automatic gain control circuit. The output end of the automatic gain control circuit is connected to the input end of the variable gain amplifier.

[0040] The automatic gain control circuit includes a peak detector and an error amplifier. The input end of the peak detector is connected to the output end of the output stage circuit. The output end of the peak detector is connected to the input end of the error amplifier. The output end of the error amplifier is connected to the input end of the variable gain amplifier. The automatic gain control circuit is used to adjust the output level of the MESM resonator, reduce the nonlinearity of the output signal, increase the power handling capability of the MEMS resonator, and reduce the phase noise of the resonator output signal.

[0041] The MEMS drive circuit converts the current signal of the MEMS resonator into a voltage signal, overcomes the loss existing in the MEMS resonator circuit, and drives the MEMS resonator to generate an oscillation signal.

[0042] The mixing circuit includes a mixer and a low-pass filter. The input end of the mixer receives the oscillation signals fa and fb generated by the MEMS drive circuit. The output end of the mixer is connected to the input end of the low-pass filter. The output end of the low-pass filter outputs the difference frequency signal fb-fa to the quantization circuit. The mixer is used to mix the oscillation signals fa and fb. The low-pass filter is used to extract the difference frequency signal of the mixed oscillation signal, to obtain the difference frequency signal fb-fa. The difference frequency signal fb-fa is one of the frequency signals of the subsequent quantization circuit frequency ratio.

[0043] The frequency division circuit is an integer N frequency divider, which is used to perform N frequency division operation on the received oscillation signal fa, to generate a frequency division signal fa / N. The frequency division signal fa / N is the other frequency signal of the subsequent quantization circuit frequency ratio.

[0044] The quantization circuit comprises a counter, a time-to-digital conversion circuit and a digital loop filter. The input of the counter receives a divided frequency signal fa / N from the frequency division circuit, and the output of the counter is connected to the input of the digital loop filter. The input of the time-to-digital conversion circuit receives a beat frequency signal fb-fa from the frequency mixing circuit, and the output of the time-to-digital conversion circuit is also connected to the input of the digital loop filter. The output of the digital loop filter outputs a temperature-related signal TDCout to the temperature compensation circuit. The counter and the time-to-digital conversion circuit realize quantization of the integer part M and the decimal part N of the frequency ratio of the quantization circuit respectively, and the specific frequency ratio M.N is obtained through the digital loop filter. The frequency ratio information contains temperature information and can be used for temperature quantization.

[0045] The temperature compensation circuit is a high-order polynomial temperature compensation circuit, which is used to digitally scale the received temperature-related signal TDCout to generate a temperature compensation TDCerror. The temperature compensation TDCerror is the temperature compensation corresponding to the current temperature, which is used for frequency correction in the input frequency synthesizer circuit.

[0046] The frequency synthesizer circuit comprises a phase-frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator, a multi-modulus divider and a Sigma-Delta modulator. The input of the Sigma-Delta modulator receives an oscillation signal fa generated by the MEMS driving circuit and a temperature compensation TDCerror generated by the temperature compensation circuit respectively, and the output of the Sigma-Delta modulator is connected to the input of the multi-modulus divider. The input of the phase-frequency detector and the charge pump receives the oscillation signal fa generated by the MEMS driving circuit, and the input of the phase-frequency detector is also connected to the output of the multi-modulus divider. The output of the phase-frequency detector is connected to the input of the charge pump. The output of the charge pump is connected to the input of the loop filter. The output of the loop filter is connected to the input of the voltage-controlled oscillator. The output of the voltage-controlled oscillator is connected to the input of the multi-modulus divider and the input of the out-of-loop frequency divider. The output of the out-of-loop frequency divider is connected to the input of the driver. The output of the driver outputs a high-stable clock signal fout. The frequency synthesizer takes the oscillation signal fa generated by the MEMS resonator as the reference clock signal, controls the output frequency through the Sigma-Delta modulator receiving the scaled temperature compensation, and generates a high-stable clock signal.

[0047] The application uses two MEMS driving circuits, mixing frequency circuits, frequency division circuits, quantization circuits, temperature compensation circuits and frequency synthesizer circuits to complete the signal processing of mixing frequency, frequency division and frequency ratio, realize the hundred times sensitivity of temperature signal, complete the millikelvin level temperature sensing precision and microkelvin level temperature resolution, so as to achieve the effect of realizing the frequency stability of ±0.1ppm in a wide temperature range through the high precision and high resolution temperature sensing compensation crystal oscillator.

[0048] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A temperature-compensated clock circuit based on multiple sensitization, characterized in that: include: Two MEMS driving circuits, driving the MEMS resonator to generate oscillation signals fa and fb respectively; The mixing circuit performs a mixing operation on the received oscillation signals fa and fb to generate a difference frequency signal fb-fa; The frequency dividing circuit divides the received oscillation signal fa by N to generate a frequency-divided signal fa / N; A quantization circuit performs a frequency ratio operation on a received difference frequency signal fb-fa and a frequency division signal fa / N to generate a temperature-dependent signal TDCout. The quantization circuit includes a counter, a time-to-digital conversion circuit, and a digital loop filter. The input of the counter receives the frequency division signal fa / N from the frequency division circuit, and the output of the counter is connected to the input of the digital loop filter. The input of the time-to-digital conversion circuit receives the difference frequency signal fb-fa from the frequency mixing circuit, and the output of the time-to-digital conversion circuit is also connected to the input of the digital loop filter. The output of the digital loop filter outputs the temperature-dependent signal TDCout to the temperature compensation circuit. The temperature compensation circuit performs digital calibration on the received temperature-related signal TDCout to generate a temperature compensation value TDCerror; The frequency synthesizer circuit performs temperature compensation on the received oscillation signal fa using the received temperature compensation amount TDCerror to generate a highly stable clock signal fout.

2. The temperature-compensated clock circuit based on multiple sensitization according to claim 1, characterized in that: The MEMS driving circuit includes: an input stage circuit, a variable gain amplifier, an output stage circuit and an automatic gain control circuit; The output end of the input stage circuit is connected to the input end of the variable gain amplifier, the output end of the variable gain amplifier is connected to the input end of the output stage circuit, the output end of the output stage circuit is connected to the input end of the automatic gain control circuit, and the output end of the automatic gain control circuit is connected to the input end of the variable gain amplifier.

3. The temperature-compensated clock circuit based on multiple sensitization according to claim 2, characterized in that: The automatic gain control circuit includes: a peak detector and an error amplifier; The input terminal of the peak detector is connected to the output terminal of the output stage circuit, and the output terminal of the peak detector is connected to the input terminal of the error amplifier, and the output terminal of the error amplifier is connected to the input terminal of the variable gain amplifier.

4. The temperature-compensated clock circuit based on multiple sensitization according to claim 1, characterized in that: The mixing circuit includes: a mixer and a low-pass filter; The input end of the mixer receives the oscillation signals fa and fb generated by the MEMS driving circuit, the output end of the mixer is connected to the input end of the low-pass filter, and the output end of the low-pass filter outputs the difference frequency signal fb-fa to the quantization circuit.

5. The temperature-compensated clock circuit based on multiple sensitization according to claim 1, characterized in that: The frequency dividing circuit is an integer-N frequency divider.

6. The temperature-compensated clock circuit based on multiple sensitization according to claim 1, characterized in that: The temperature compensation circuit is a high-order polynomial temperature compensation circuit.

7. The temperature-compensated clock circuit based on multiple sensitization according to claim 1, characterized in that: The frequency synthesizer circuit includes: a frequency and phase detector, a charge pump, a loop filter, a voltage-controlled oscillator, a multi-mode frequency divider and a Sigma-Delta modulator; The input end of the Sigma-Delta modulator receives the oscillation signal fa generated by the MEMS driving circuit and the temperature compensation value TDCerror generated by the temperature compensation circuit respectively, and the output end of the Sigma-Delta modulator is connected to the input end of the multi-mode frequency divider, the input end of the phase frequency detector receives the oscillation signal fa generated by the MEMS driving circuit, and the input end of the phase frequency detector is also connected to the output end of the multi-mode frequency divider, the output end of the phase frequency detector is connected to the input end of the charge pump, the output end of the charge pump is connected to the input end of the loop filter, the output end of the loop filter is connected to the input end of the voltage-controlled oscillator, the output end of the voltage-controlled oscillator is connected to the input end of the multi-mode frequency divider, and the output end of the voltage-controlled oscillator is also connected to the input end of the out-of-loop frequency divider, the output end of the out-of-loop frequency divider is connected to the input end of the driver, and the output end of the driver outputs a highly stable clock signal fout.

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