High-precision RC oscillator circuit

Abstract

The invention belongs to the technical field of integrated circuits, and particularly relates to a high-precision RC oscillator circuit. According to the invention, the influence of the delay introduced by the limited bandwidth of the comparator and the delay of a logic circuit is eliminated from the circuit structure, and high frequency precision and stability can be obtained: by designing the adjustable capacitor, the actual output clock frequency can be discretely adjusted; by designing the temperature-adjustable resistor, the temperature coefficient of the resistor can be flexibly adjusted, so that the variation of the output clock frequency along with the temperature can be ignored, and the stability of the output clock frequency is improved. The system is especially suitable for some low-cost and low-power-consumption application scenes, and has the characteristics of low cost, high integration level and good stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and particularly relates to a high-precision RC oscillator circuit. Background Art

[0002] Oscillators can generate stable clock signals for synchronizing and controlling various operations in logic circuits, playing an important role in chips. Currently, commonly used oscillators can be roughly divided into two categories. One is resonant oscillators such as crystal oscillators, which have the advantages of good frequency stability and high precision, but are difficult to integrate. The other is relaxation oscillators such as RC oscillators. Different from resonant oscillators, relaxation oscillators mainly rely on nonlinear devices to trigger the signal to flip periodically. Most of their structures can be implemented through standard CMOS processes and have a high integration level, and can make full use of the convenience brought by the evolution of the process technology. Therefore, in low-cost and low-power application scenarios such as Internet of Things chips, smart homes, and low-power SOCs, high-precision RC relaxation oscillators are often used.

[0003] As an easily integrated reference clock source with strong anti-mechanical shock ability, RC relaxation oscillators are widely used in low-cost and low-power scenarios. However, their deficiencies in stability limit their applications in high-precision scenarios. Therefore, the research on RC relaxation oscillators basically focuses on aspects such as temperature stability, power supply stability, and process stability. For traditional voltage-mode RC relaxation oscillators, their basic principle is to charge a capacitor C with a reference current I. When the capacitor voltage reaches the reference voltage V, this period is half a cycle. By alternately charging and discharging the capacitor, a square wave output is finally formed. The implementation formula is: Since the frequency f is inversely proportional to the time T, the voltage V is generally equal to the product of the current I and the resistance R. Finally, the formula for the output frequency can be obtained: It can be seen from the formula that the output frequency is not sensitive to the power supply voltage, and the fluctuations of the output frequency with the process and temperature are determined by the resistance and capacitance. However, in actual situations, the finite gain of the comparator, the offset voltage of the comparator, the finite bandwidth of the comparator, the delay of the logic circuit, the switch conduction time, etc. will introduce a delay td within the half cycle of the clock tot , resulting in the actual output frequency formula being: These delays will change with the process and temperature, thus affecting the frequency accuracy. Moreover, as the output clock frequency increases, the proportion of these delays also becomes larger and larger. Summary of the Invention

[0004] In order to solve the above problems of the prior art, the present invention provides a high-precision RC oscillator circuit.

[0005] A high-precision RC oscillator circuit includes a positive temperature coefficient current module and an oscillator module, and the positive temperature coefficient current module and the oscillator module are integrated on the same semiconductor module.

[0006] The positive temperature coefficient current module includes a positive temperature coefficient current generator, a first current source, a second current source, and a third current source. The positive temperature coefficient current generator is connected to the input ends of the first current source, the second current source, and the third current source. The output end of the first current source is connected to one end of a temperature-adjustable resistor and the input end of a first low-pass filter. The output end of the second current source is connected to one end of a frequency-voltage converter and the input end of a second low-pass filter. The third current source is connected to the bias end of an integrator.

[0007] The positive temperature coefficient current module provides three paths of current for the oscillator module, which are respectively used to provide the reference current of the temperature-adjustable resistor, the charging current of the frequency-voltage converter, and the bias current of the error amplifier. Among them, the currents of the first current source and the second current source are equal.

[0008] The oscillator module includes a temperature-adjustable resistor, a frequency-voltage converter, a first low-pass filter, a second low-pass filter, an integrator, a voltage-controlled oscillator, an N-frequency division circuit, and a non-overlapping clock generation circuit.

[0009] One end of the temperature-adjustable resistor is connected to the input end of the first low-pass filter and the output end of the first current source, and the other end is grounded; one end of the frequency-voltage converter is connected to the input end of the second low-pass filter and the output end of the second current source, and the other end is grounded; the output end of the first low-pass filter is connected to the positive input end of the integrator, and the output end of the second low-pass filter is connected to the negative input end of the integrator; the output end of the integrator is connected to the input end of the voltage-controlled oscillator; the first output end of the voltage-controlled oscillator is connected to the input end of the N-frequency division circuit, and at the same time the second output end outputs a clock signal CLKOUT; the output end of the N-frequency division circuit is connected to the input end of the non-overlapping clock generation circuit; the output end of the non-overlapping clock generation circuit is connected to the frequency-voltage converter.

[0010] The temperature-adjustable resistor includes a first resistor and a second resistor, and its total resistance is R = R1 + R2; the resistance of the first resistor is R1, and the resistance of the second resistor is R2; one end of the second resistor is connected to one end of the first resistor, and the other end is grounded; the other end of the first resistor is connected to the first current source and the first low-pass filter.

[0011] The integrator includes an error amplifier and a fourth capacitor; the positive input terminal of the error amplifier is connected to the output terminal of the first low-pass filter; the negative input terminal of the error amplifier is connected to the output terminal of the second low-pass filter; the output terminal of the error amplifier is connected to the input terminal of the voltage-controlled oscillator and one end of the fourth capacitor; the other end of the fourth capacitor is grounded; the bias terminal of the error amplifier is connected to the third current source.

[0012] The oscillator module is used to generate a high-precision clock signal CLKOUT. By integrating an adjustable capacitor, the output clock frequency can be discretely adjusted; by integrating a temperature-adjustable resistor, the oscillator module can achieve temperature regulation.

[0013] Furthermore, the positive temperature coefficient current generator generates a positive temperature coefficient current, and its second-order temperature coefficient is less than that of the zero temperature coefficient current.

[0014] Furthermore, the first current source, the second current source, and the third current source adopt a current mirror structure and are replicated from the output current of the positive temperature coefficient current generator.

[0015] Furthermore, the frequency-voltage converter is used to convert the clock signals clk1 and clk2 output by the non-overlapping clock generation circuit into voltages, and includes a first switch S1, a second switch S2, a first capacitor, and a second capacitor. One end of the second switch S2 is respectively connected to one end of the first switch S1 and one end of the first capacitor, and the other end is grounded; the other end of the first capacitor is grounded; the other end of the first switch S1 is connected to the output terminal of the second current source, one end of the second capacitor, and the input terminal of the second filter; the other end of the second capacitor is grounded.

[0016] The frequency-voltage converter transfers charge in each switching cycle, which is equivalent to a resistor. If the output clock frequency of the non-overlapping clock generation circuit is f1, the capacitance value of the first capacitor is C1, and the equivalent resistance value Z eq of the frequency-voltage converter is calculated as follows:

[0017]

[0018] Furthermore, the first capacitor is an n-bit adjustable capacitor array. In the first capacitor, the capacitance value of the fixed capacitor is C10. At room temperature, the capacitance value of the i-th capacitor in the first capacitor is C1[i]=2 i *C0, where C0 is the capacitance value of the unit capacitor. SC[i] is the control signal of the i-th capacitor in the first capacitor. When SC[i] is at a high level, the i-th capacitor is connected to the first capacitor; otherwise, the i-th capacitor is disconnected. The calculation formula for the capacitance value C1 of the first capacitor is as follows:

[0019]

[0020] Further, in the adjustable resistor:

[0021] The first resistor is an n-bit adjustable positive temperature coefficient resistor array. In the first resistor, the resistance value of the fixed resistor is R10. At room temperature, the resistance value of the i-th resistor in the first resistor is R1[i] = 2 i *R0, where R0 is the resistance value of the unit resistor. SRP[i] is the control signal of the i-th resistor in the first resistor. When SRP[i] is at a high level, the i-th resistor is connected to the first resistor; otherwise, the i-th resistor is disconnected. The resistor array of the first resistor is composed of the same kind of positive temperature coefficient resistors, and the temperature coefficient of this kind of resistor is K1. T represents the temperature. Then, the calculation formula for the resistance value of the first resistor is as follows:

[0022]

[0023] The second resistor is an n-bit adjustable negative temperature coefficient resistor array. In the second resistor, the resistance value of the fixed resistor is R20. At room temperature, the resistance value of the i-th resistor in the second resistor is R2[i] = 2 i *R0, where R0 is the resistance value of the unit resistor. SRN[i] is the control signal of the i-th resistor in the second resistor. SRN[i] and SRP[i] are complementary signals, that is, when SRN[i] is at a low level, SRP[i] is at a high level, and vice versa. The resistor array of the second resistor is composed of the same kind of negative temperature coefficient resistors, and the temperature coefficient of this kind of resistor is -K2. Then, the calculation formula for the resistance value of the second resistor is as follows:

[0024]

[0025] Further, the control logic of the frequency-voltage converter is as follows:

[0026] When switch S1 is turned on and switch S2 is turned off, the second current source charges the first capacitor. When the voltage across the first capacitor reaches the reference voltage V REF At this time, the calculation formula for the charge quantity at both ends of the first capacitor is: Q1 = C1 * V REF .

[0027] After that, the switch is switched, switch S2 is turned on, and switch S1 is turned off, and the voltage across the first capacitor starts to discharge. When the voltage across the first capacitor becomes 0V, the calculation formula for the charge quantity at both ends of the first capacitor is: Q2 = C1 * 0, and one cycle ends.

[0028] Within one clock cycle T1, the calculation formula for the total charge quantity transferred by the first capacitor is: ΔQ = C1 * V REF . The equivalent current Ieq is equal to the ratio of the total charge quantity transferred by the first capacitor to the clock cycle T1, and its calculation formula is: The output clock period T1 of the non-overlapping clock generation circuit is inversely proportional to the frequency f1. Therefore, the calculation formula for the equivalent current can be rewritten as: Ieq = C1 * V REF * f1. The equivalent resistance value Req of the frequency-voltage converter is equal to the ratio of the change in the voltage across the first capacitor to the equivalent current:

[0029] The working logic of the above high-precision RC oscillator circuit is as follows:

[0030] When the output signal EN of the enable terminal of the entire RC oscillator circuit is at a low level, the circuit is in a sleep state.

[0031] When the output signal EN of the enable terminal is at a high level, the positive temperature coefficient current module starts and provides current to the oscillator module. The current output by the first current source passes through the adjustable temperature resistor to establish a reference voltage V REF , and its calculation formula is:

[0032] V REF = I1 * R = I1 * (R1 + R2)

[0033] Among them, I1 is the current value of the current output by the first current source. At the same time, the input voltage of the voltage-controlled oscillator drops rapidly. When it is lower than a certain value, the output clock frequency of the voltage-controlled oscillator jumps rapidly to the maximum output frequency. After that, the output clock frequency of the non-overlapping clock generation circuit also reaches the maximum value, the equivalent resistance of the frequency-voltage converter reaches the minimum, and the output voltage of the second low-pass filter also correspondingly becomes the minimum value. Therefore, the output voltage of the integrator gradually rises, causing the output frequency of the voltage-controlled oscillator to gradually decrease.

[0034] When the entire RC oscillator circuit is stable, the voltage V N at the negative input terminal of the integrator is equal to the product of the current value I2 of the current output by the second current source and the equivalent resistance value Req of the frequency-voltage converter, and its calculation formula is Moreover, the current values of the current output by the first current source and the second current source are equal, that is, I1 = I2. At the same time, the voltage V N at the negative input terminal of the integrator is also equal to the reference voltage V REF , that is, V N = V REF . Therefore, the calculation formula for the output clock frequency of the non-overlapping clock generation circuit can be obtained:

[0035] In the oscillator module, the frequency-voltage converter, low-pass filter, integrator, voltage-controlled oscillator, N-divider circuit, and non-overlapping clock generation circuit form a feedback loop. Through the frequency multiplication function of the feedback loop, the output clock frequency of the RC oscillator circuit can reach: According to the working state after the RC oscillator circuit is stabilized, the output clock frequency is independent of the delay introduced by the limited bandwidth of the comparator and the delay of the logic circuit.

[0036] In summary, the present invention eliminates the influence of the delay introduced by the limited bandwidth of the comparator and the delay of the logic circuit from the circuit structure, and can obtain high frequency accuracy and stability: by designing an adjustable capacitor, the actual output clock frequency can be discretely adjusted; by designing a temperature-adjustable resistor, the temperature coefficient of the resistor can be flexibly adjusted, so that the change in the output clock frequency with temperature can be ignored, thereby improving the stability of the output clock frequency. Description of the Drawings

[0037] Figure 1 is a schematic circuit diagram of the present invention.

[0038] Figure 2 is a schematic diagram of the working waveform of the present invention.

[0039] Figure 3 is a schematic diagram showing the change of the output frequency with temperature under different process corners of the present invention. Detailed Embodiments

[0040] To clearly describe the purpose, technical solution and advantages of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention, and the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations. The technical solutions in the present invention will be further described below in conjunction with the drawings and embodiments.

[0041] A high-precision RC oscillator circuit, the specific circuit structure in this embodiment is as Figure 1 shown, including a positive temperature coefficient current module and an oscillator module.

[0042] The positive temperature coefficient current module provides 3 paths of current for the oscillator module, which are respectively used to provide the reference current I1 of the temperature-adjustable resistor, the charging current I2 of the frequency-voltage converter, and the bias current I3 of the error amplifier; among them, I1 = I2.

[0043] The oscillator module is used to generate a high-precision clock signal CLKOUT. By integrating an adjustable capacitor, the output clock frequency can be discretely adjusted; by integrating a temperature-adjustable resistor, the oscillator module realizes temperature adjustment.

[0044] As an embodiment of the present invention:

[0045] The adjustable-temperature resistor adopts a structure of a 6-bit series resistor array, with the adjustment range of the temperature coefficient being from -150 ppm / °C to 35 ppm / °C, and the adjustment accuracy of the temperature coefficient being less than 6.4 ppm / °C.

[0046] The frequency-voltage converter includes a first switch S1, a second switch S2, a first capacitor (C1), and a second capacitor (C2). The first capacitor C1 adopts an 8-bit parallel capacitor array, which can achieve a frequency adjustment range of ±40%, and the frequency adjustment accuracy is 0.5%.

[0047] The first low-pass filter and the second low-pass filter adopt a first-order RC series network, and the resistor and capacitor parameters are exactly the same to avoid errors introduced by inconsistent low-pass filters.

[0048] The integrator includes an error amplifier and a fourth capacitor (C4). The error amplifier adopts a folded cascode amplifier with a P input and a low-power consumption design.

[0049] The voltage-controlled oscillator adopts a power supply-tuned ring oscillator structure. The frequency division circuit adopts an eight-frequency division structure. Among them, the D flip-flop adopts a clock-controlled D flip-flop to obtain lower power consumption.

[0050] In actual production, process deviations will cause the output clock frequency of the RC oscillator circuit to deviate from the target value. To adjust the output clock frequency, the first capacitor C1 adopts an adjustable capacitor array, and its capacitance value can be adjusted through the input code value, so that different batches of RC oscillators can achieve higher frequency accuracy through adjustment. The capacitor array can be adjusted through sensors and digital circuits, and calibration of the RC oscillator can be achieved.

[0051] The output clock frequency of the RC oscillator circuit is related to the temperature coefficients of the resistor and the capacitor. By reasonably adjusting the temperature coefficient of the adjustable resistor, the product of the capacitor and the resistor can be considered a fixed value, so that the change amount of the product of the capacitor and the resistor with temperature can be ignored. When adjusting the temperature coefficient of the adjustable-temperature resistor, the total resistance value of the adjustable-temperature resistor remains unchanged under typical conditions. The adjustable steps of the first resistor and the second resistor are consistent, that is, when adjusting, if the first resistor increases the preset step value RT, then the second resistor decreases the preset step value RT, and vice versa. The frequency can be kept constant at 25°C during temperature characteristic trimming. The adjustment accuracy is determined according to project requirements, and different chips have different requirements for the oscillator temperature characteristics. According to the calculation formula of R, the adjustment accuracy of the temperature characteristics can be controlled by setting the adjustable steps of the first resistor and the second resistor. When the adjustable steps of the first resistor and the second resistor are small enough, the design of a high-precision RC oscillator circuit can be satisfied.

[0052] In this embodiment, the working waveforms of the high-precision RC oscillator circuit are as follows Figure 2 as shown.

[0053] When the output signal EN of the enable terminal of the entire RC oscillator circuit is at a low level, the output clock signal is at a low level, and its frequency is 0 MHz.

[0054] After the output signal EN of the enable terminal becomes high, the positive temperature coefficient current module starts and provides current to the oscillator module. The current output by the first current source passes through the adjustable temperature resistor to establish the reference voltage V REF . At the same time, the input voltage of the voltage-controlled oscillator drops rapidly. When it is lower than a certain value, the output clock frequency of the voltage-controlled oscillator jumps rapidly to the maximum output frequency. Subsequently, the output clock frequency of the non-overlapping clock generation circuit also reaches the maximum value, the equivalent resistance of the frequency-voltage converter reaches the minimum, and the output voltage of the second low-pass filter also correspondingly becomes the minimum value. Thus, the output voltage of the integrator gradually rises, causing the output frequency of the voltage-controlled oscillator to gradually decrease. When the entire RC oscillator circuit stabilizes, the output clock signal is a typical square wave.

[0055] In this embodiment, the variation of the output frequency of the high-precision RC oscillator with temperature under different process corners is as follows Figure 3 as shown. Adjusting the capacitance value of the first capacitor can adjust the output clock frequency. By adjusting the capacitance value of the first capacitor, the output clock frequency can be adjusted within the range of 40 MHz ± 0.3% under different process corners. For chips in different application scenarios, their requirements for the accuracy of the RC oscillator are different. By setting the adjustment step of the first capacitor, the trimming accuracy of the output clock frequency can be controlled to obtain the target frequency accuracy. For factors such as temperature coefficient and current mirror mismatch that cause fluctuations in the temperature coefficient of the output clock frequency under different process corners, adjusting the resistance values of the first resistor and the second resistor can adjust the temperature coefficient of the output clock frequency. When performing temperature characteristic adjustment, single-point calibration can be performed, that is, keeping the output clock frequency at 25°C constant.

[0056] As can be seen from the above embodiments, the present invention eliminates the influence of the delay introduced by the limited bandwidth of the comparator and the delay of the logic circuit from the circuit structure, and can obtain high frequency accuracy and stability: by designing an adjustable capacitor, the actual output clock frequency can be discretely adjusted; by designing an adjustable temperature resistor, the temperature coefficient of the resistor can be flexibly adjusted, making the change in the output clock frequency with temperature negligible, thereby improving the stability of the output clock frequency. The present invention is particularly suitable for some low-cost and low-power consumption application scenarios, and has the characteristics of low cost, high integration, and good stability.

Claims

1. A high-precision RC oscillator circuit, characterized in that: Includes a positive temperature coefficient current module and an oscillator module; The positive temperature coefficient current module comprises a positive temperature coefficient current generator, a first current source, a second current source and a third current source; the positive temperature coefficient current generator is connected to the input end of the first current source, the input end of the second current source and the input end of the third current source; the output end of the first current source is connected to one end of the adjustable temperature resistor and the input end of the first low-pass filter; the output end of the second current source is connected to one end of the frequency-voltage converter and the input end of the second low-pass filter; the third current source is connected to the bias end of the integrator; The positive temperature coefficient current module provides three currents to the oscillator module, which are used to provide a reference current for the adjustable temperature resistor, a charging current for the frequency voltage converter, and a bias current for the error amplifier; wherein the currents of the first current source and the second current source are equal; The oscillator module includes an adjustable temperature resistor, a frequency-to-voltage converter, a first low-pass filter, a second low-pass filter, an integrator, a voltage-controlled oscillator, an N-frequency divider circuit, and a non-overlapping clock generation circuit; One end of the adjustable temperature resistor is connected to the input end of the first low-pass filter and the output end of the first current source, and the other end is grounded; one end of the frequency-voltage converter is connected to the input end of the second low-pass filter and the output end of the second current source, and the other end is grounded; the output end of the first low-pass filter is connected to the positive input end of the integrator, and the output end of the second low-pass filter is connected to the negative input end of the integrator; the output end of the integrator is connected to the input end of the voltage-controlled oscillator; the first output end of the voltage-controlled oscillator is connected to the input end of the N-frequency dividing circuit, and the second output end outputs the clock signal CLKOUT; the output end of the N-frequency dividing circuit is connected to the input end of the non-overlapping clock generating circuit; the output end of the non-overlapping clock generating circuit is connected to the frequency-voltage converter; The adjustable temperature resistor includes a first resistor and a second resistor, and the total resistance thereof is R=R1+R2; the resistance of the first resistor is R1, and the resistance of the second resistor is R2; one end of the second resistor is connected to one end of the first resistor, and the other end is grounded; the other end of the first resistor is connected to a first current source and a first low-pass filter; The integrator includes an error amplifier and a fourth capacitor; the positive input terminal of the error amplifier is connected to the output terminal of the first low-pass filter; the negative input terminal of the error amplifier is connected to the output terminal of the second low-pass filter; the output terminal of the error amplifier is connected to the input terminal of the voltage-controlled oscillator and one end of the fourth capacitor; the other end of the fourth capacitor is grounded; the bias terminal of the error amplifier is connected to the third current source; The oscillator module is used to generate a high-precision clock signal CLKOUT. The output clock frequency can be discretely adjusted through a built-in adjustable capacitor. The oscillator module can achieve temperature regulation through a built-in adjustable temperature resistor.

2. The high-precision RC oscillator circuit as claimed in claim 1, characterized in that: The positive temperature coefficient current generator generates a positive temperature coefficient current, whose second-order temperature coefficient is smaller than the zero temperature coefficient current.

3. The high-precision RC oscillator circuit as claimed in claim 1, characterized in that: The first current source, the second current source and the third current source adopt a current mirror structure and are obtained by copying the output current of the positive temperature coefficient current generator.

4. The high-precision RC oscillator circuit as claimed in claim 1, characterized in that: The frequency-to-voltage converter is used to convert the clock signals clk1 and clk2 output by the non-overlapping clock generating circuit into voltages, and includes a first switch S1, a second switch S2, a first capacitor and a second capacitor; One end of the second switch S2 is respectively connected to one end of the first switch S1 and one end of the first capacitor, and the other end is grounded; the other end of the first capacitor is grounded; the other end of the first switch S1 is connected to the output end of the second current source, one end of the second capacitor and the input end of the second filter; The other end of the second capacitor is grounded; The frequency voltage converter carries charge in each switching cycle, which is equivalent to a resistor; if the output clock frequency of the non-overlapping clock generation circuit is f1, the capacitance of the first capacitor is C1, and the equivalent resistance of the frequency voltage converter is Z eq The calculation formula is written as:

5. The high-precision RC oscillator circuit as claimed in claim 1, characterized in that: The first capacitor is an n-bit adjustable capacitor array; in the first capacitor, the capacitance of the fixed capacitor is C10, and at room temperature, the capacitance of the i-th capacitor in the first capacitor is C1[i]=2 i *C0, C0 is the capacitance of the unit capacitor; SC[i] is the control signal of the i-th capacitor in the first capacitor. When SC[i] is at a high level, the i-th capacitor is connected to the first capacitor; otherwise, the i-th capacitor is disconnected. The calculation formula of the first capacitor value C1 is as follows:

6. The high-precision RC oscillator circuit as claimed in claim 1, characterized in that: In the adjustable temperature resistor: The first resistor is an n-bit adjustable positive temperature coefficient resistor array. In the first resistor, the resistance of the fixed resistor is R10; at room temperature, the resistance of the i-th resistor in the first resistor is R1[i]=2 i *R0, R0 is the resistance value of the unit resistor; SRP[i] is the control signal of the i-th resistor in the first resistor; When SRP[i] is high, the i-th resistor is connected to the first resistor; On the contrary, the i-th resistor is disconnected; the resistor array of the first resistor is composed of the same positive temperature coefficient resistor, the temperature coefficient of this resistor is K1, T represents the temperature, and the calculation formula of the resistance value of the first resistor is as follows: The second resistor is an n-bit adjustable negative temperature coefficient resistor array. In the second resistor, the resistance of the fixed resistor is R20; at room temperature, the resistance of the i-th resistor in the second resistor is R2[i]=2 i *R0, R0 is the resistance value of the unit resistor; SRN[i] is the control signal of the i-th resistor in the second resistor; SRN[i] and SRP[i] are complementary signals, that is, when SRN[i] is low, SRP[i] is high, and vice versa; the resistor array of the second resistor is composed of the same negative temperature coefficient resistor, the temperature coefficient of this resistor is -K2, and the calculation formula of the second resistor value is as follows:

7. The high-precision RC oscillator circuit according to claim 1, characterized in that: The control logic of the frequency-to-voltage converter is: When the switch S1 is turned on and the switch S2 is turned off, the second current source charges the first capacitor; when the voltage across the first capacitor reaches the reference voltage V REF When the charge across the first capacitor is calculated as: Q1 = C1 * V REF ; Afterwards, the switch is switched, switch S2 is turned on, switch S1 is turned off, and the voltage across the first capacitor begins to discharge; when the voltage across the first capacitor becomes 0V, the calculation formula for the charge across the first capacitor is: Q2=C1*0, and one cycle ends; In a clock cycle T1, the total amount of charge transferred by the first capacitor is calculated as: ΔQ = C1*V REF The equivalent current Ieq is equal to the ratio of the total amount of charge moved by the first capacitor to the clock period T1, and its calculation formula is: The output clock period T1 of the non-overlapping clock generation circuit is inversely proportional to the frequency f1; therefore, the calculation formula of the equivalent current can be rewritten as: Ieq = C1*V REF *f1; The equivalent resistance value Req of the frequency-to-voltage converter is equal to the ratio of the voltage change across the first capacitor to the equivalent current:

8. The high-precision RC oscillator circuit according to claim 1, characterized in that: The specific working logic is: When the output signal EN of the enable terminal of the entire RC oscillator circuit is at a low level, the circuit is in a dormant state; When the output signal EN of the enable terminal is at a high level, the positive temperature coefficient current module starts to provide current to the oscillator module; the current output by the first current source passes through the adjustable temperature resistor to establish a reference voltage V REF , and its calculation formula is: In REF =I1*R=I1*(R1+R2) Wherein, I1 is the current value of the output current of the first current source; at the same time, the input voltage of the voltage-controlled oscillator drops rapidly; when it is lower than a certain value, the output clock frequency of the voltage-controlled oscillator jumps rapidly to the maximum output frequency; then, the output clock frequency of the non-overlapping clock generation circuit also reaches the maximum value, the equivalent resistance of the frequency-to-voltage converter reaches the minimum, and the output voltage of the second low-pass filter also becomes the minimum value accordingly; thus, the output voltage of the integrator gradually rises, causing the output frequency of the voltage-controlled oscillator to gradually decrease; When the entire RC oscillator circuit is stable, the voltage V N = The product of the current value I2 of the output current of the second current source and the equivalent resistance value Req of the frequency-to-voltage converter, which is calculated as follows: And I1=I2; at the same time, the negative input voltage of the integrator V N It is also equal to the reference voltage V REF , that is, V N =V REF ; Therefore, the calculation formula for the output clock frequency of the non-overlapping clock generation circuit is: In the oscillator module, the frequency-to-voltage converter, low-pass filter, integrator, voltage-controlled oscillator, N-frequency divider circuit and non-overlapping clock generation circuit form a feedback loop; through the frequency multiplication function of the feedback loop, the output clock frequency of the RC oscillator circuit can reach: According to the working state of the RC oscillator circuit after stabilization, the output clock frequency is independent of the delay introduced by the limited bandwidth of the comparator and the delay of the logic circuit.

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