Oscillator circuit for generating a constant output frequency signal, and chip

Abstract

The embodiment of the present application provides an oscillator circuit for generating constant output frequency signal and a chip, and belongs to the chip technical field.The oscillator circuit for generating constant output frequency signal comprises an oscillation wave generating circuit and a feedback frequency modulation circuit, wherein the first input end of the feedback frequency modulation circuit is connected with the output end of the oscillation wave generating circuit, the output end of the feedback frequency modulation circuit is connected with the voltage control end of the oscillation wave generating circuit, the feedback frequency modulation circuit receives the output of the oscillation wave generating circuit as a feedback signal, and adjusts the supply voltage of the feedback frequency modulation circuit output to the oscillation wave generating circuit according to the feedback signal, thereby controlling the oscillation wave generating circuit to output a constant frequency signal.The embodiment of the present application provides a ring-shaped oscillation circuit with feedback adjustment which can generate stable output frequency, and the square wave frequency output by the ring-shaped oscillation circuit does not change with process conditions and temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chip, in particular to an oscillator circuit for generating constant output frequency signal and a chip. BACKGROUND

[0002] The oscillator circuit generates an alternating current signal of a certain frequency by converting a direct current voltage into an alternating current voltage. The structural feature of the oscillator circuit is that there is no external circuit input end. A feedback network exists in the circuit to feed back the output to the input to form oscillation. At the same time, a frequency selection network exists to ensure that the oscillator can work at a certain frequency. The functions of the oscillator circuit in the overall circuit mainly include: generating a stable clock frequency to determine the working frequency of the control module in the overall circuit; realizing the conversion between direct current and alternating current to provide energy for the device where the circuit is located; and being used for transmitting of wireless transmitting devices.

[0003] A common ring oscillator is formed by connecting odd number of inverters in a ring. The principle of generating an oscillation signal by the ring oscillator is to utilize the inherent transmission delay of the gate circuit. The ring oscillator does not have a steady state form because the input and output of any inverter cannot be stabilized at a high level or a low level in a static state, but can only be between a high level and a low level in an amplification state. The disadvantages of the conventional ring wave oscillator include: the delay time of the inverter circuit is very short, it is difficult to obtain a lower oscillation frequency, and the frequency of the inverter circuit is not easy to adjust; the output frequency of the inverter circuit changes with temperature, different process conditions and even different power supply voltages, resulting in that the output frequency of the ring oscillator cannot be stabilized. SUMMARY

[0004] The purpose of the embodiment of the present application is to provide an oscillator circuit for generating constant output frequency signal, which can output a constant frequency signal to overcome the disadvantages of the existing ring oscillator.

[0005] In order to achieve the above-mentioned purpose, the embodiment of the present application provides an oscillator circuit for generating constant output frequency signal, which comprises an oscillation wave generating circuit and a feedback frequency modulation circuit. The first input end of the feedback frequency modulation circuit is connected to the output end of the oscillation wave generating circuit. The output end of the feedback frequency modulation circuit is connected to the voltage control end of the oscillation wave generating circuit. The feedback frequency modulation circuit receives the output of the oscillation wave generating circuit as a feedback signal, and adjusts the supply voltage output to the oscillation wave generating circuit according to the feedback signal, thereby controlling the oscillation wave generating circuit to output a constant frequency signal.

[0006] Optionally, the feedback frequency modulation circuit comprises an error amplifier, a temperature-insensitive device and a switched-capacitor resistance circuit, wherein one end of the switched-capacitor resistance circuit is the first input end of the feedback frequency modulation circuit, the output end of the error amplifier is the output end of the feedback frequency modulation circuit, and the non-inverting input terminal VN of the error amplifier is connected to the line between the switched-capacitor resistance circuit and the temperature-insensitive device.

[0007] Optionally, the adjustment of the supply voltage output by the feedback frequency modulation circuit to the oscillation wave generation circuit according to the feedback signal to control the oscillation wave generation circuit to output a constant frequency signal comprises: when the input voltage of the non-inverting input terminal VN of the error amplifier is less than the input voltage of the inverting input terminal VP of the error amplifier, the supply voltage output by the error amplifier is reduced, so that the frequency of the feedback signal output by the oscillation wave generation circuit is reduced, wherein the input voltage of the non-inverting input terminal VN is the product of the equivalent resistance of the switched-capacitor resistance circuit and the current of the constant current source; the equivalent resistance of the switched-capacitor resistance circuit is increased, so that the input voltage of the non-inverting input terminal VN of the error amplifier is increased, thereby keeping the input voltage of the non-inverting input terminal VN equal to the input voltage of the inverting input terminal VP, and the oscillation wave generation circuit outputs a constant frequency signal.

[0008] Optionally, the switched-capacitor resistance circuit comprises a PMOS, an NMOS, a first capacitor and a second capacitor, the line between the gate of the PMOS and the gate of the NMOS is one end of the switched-capacitor resistance circuit, the line between the source of the PMOS and the source of the NMOS is connected to one end of the first capacitor, the other end of the first capacitor is grounded, and the line between the drain of the PMOS and the drain of the NMOS is connected to one end of the second capacitor, the other end of the second capacitor is grounded.

[0009] Optionally, the temperature-insensitive device is a constant current source or a resistor.

[0010] Optionally, the oscillator circuit for generating a constant output frequency signal further comprises a spread spectrum module, the input end of the spread spectrum module is connected to a constant power supply, the output end of the spread spectrum module is connected to the inverting input terminal VP of the error amplifier, the output end of the oscillation wave generation circuit is connected to the clock control end of the spread spectrum module, and the spread spectrum module outputs a spread spectrum signal as the input voltage of the inverting input terminal VP of the error amplifier to reduce electromagnetic interference.

[0011] Optionally, the spread spectrum module comprises a state machine circuit and a voltage dividing resistance circuit, wherein the input end of the state machine circuit is the clock control end of the spread spectrum module, the number of output ends of the state machine circuit is one or more, the number of voltage dividing resistance circuits is one or more, and each output end of the state machine circuit is connected to one voltage dividing resistance circuit.

[0012] Optionally, the oscillation wave generating circuit comprises a ring oscillator and a shaping circuit, wherein an output terminal of the ring oscillator is connected to an input terminal of the shaping circuit, and an output terminal of the shaping circuit is the output terminal of the oscillator circuit for generating the constant output frequency signal.

[0013] Optionally, the shaping circuit comprises a filter and a buffer connected in sequence, wherein the filter comprises a capacitor and a first inverter connected in parallel, and the buffer comprises two second inverters connected in series.

[0014] The embodiment of the present application also provides a chip comprising a clock module, wherein the clock module comprises the oscillator circuit for generating the constant output frequency signal according to any one of the above.

[0015] Through the above technical solution, the embodiment of the present application provides the ring oscillator circuit with feedback adjustment capable of generating stable output frequency, and the frequency of the square wave output by the ring oscillator circuit does not change with process conditions and temperature; meanwhile, the spread spectrum technology is adopted to realize lower electromagnetic interference, higher signal accuracy and smaller power consumption.

[0016] Other features and advantages of the embodiment of the present application will be described in detail in the following specific implementation part. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are used to provide further understanding of the embodiment of the present application, and constitute a part of the specification, and are used to explain the embodiment of the present application together with the following specific implementation, but do not constitute the limitation to the embodiment of the present application. In the drawings:

[0018] Figure 1 is a structural schematic diagram of the existing ring oscillator;

[0019] Figure 2 is a structural schematic diagram of the oscillator circuit for generating the constant output frequency signal provided by the embodiment of the present application;

[0020] Figure 3 is a structural schematic diagram of the oscillator circuit for generating the constant output frequency signal;

[0021] Figure 4 is a schematic diagram of the voltage generated by the example switched capacitor resistor circuit and temperature insensitive device voltage divider;

[0022] Figure 5 is a structural schematic diagram of the example spread spectrum module;

[0023] Figure 6 is a structural schematic diagram of the example oscillation wave generating circuit.

[0024] Explanation of reference numerals in the attached figures

[0025] 10 - Oscillating wave generating circuit; 20 - Feedback frequency modulation circuit. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0027] Traditional ring oscillator circuits such as Figure 1 As shown, it is formed by connecting an odd number of inverters (e.g., 3 inverters) end to end. Assume V 11 A tiny positive transition occurs in the voltage level. After transmission through the first inverter I1, the delay time is t. pd After that, V 12 This generates a large negative transition, which is then transmitted through the second inverter I2, with a delay of t. pd After that, V 13 This results in a larger jump, which occurs after transmission through the third inverter I3, and after a delay of tpd, at V. O A larger negative transition is generated at this point and fed back to the input of the first inverter I1, and then after 3t... pd V 11 The voltage will then jump to a high level. This cyclical change eventually generates self-excited oscillation. The oscillation period of this traditional ring oscillator is T = 6t. pd The disadvantages of traditional ring oscillators include: the inverter circuit has a very short delay time, making it difficult to obtain a low oscillation frequency; at the same time, the inverter frequency is not easy to adjust; the output frequency of the inverter circuit changes with temperature, different process conditions, and even different supply voltages, resulting in an unstable output frequency of the ring oscillator.

[0028] Figure 2 This is a schematic diagram of the oscillator circuit for generating a constant output frequency signal provided in an embodiment of the present invention. Please refer to it. Figure 2 The oscillator circuit for generating a constant output frequency signal may include an oscillation wave generation circuit 10 and a feedback frequency modulation circuit 20.

[0029] The first input terminal of the feedback frequency modulation circuit 20 is connected to the output terminal of the oscillation wave generating circuit 10, and the output terminal of the feedback frequency modulation circuit 20 is connected to the voltage control terminal of the oscillation wave generating circuit 10. The feedback frequency modulation circuit 20 receives the output of the oscillation wave generating circuit 10 as a feedback signal, and adjusts the power supply voltage output by the feedback frequency modulation circuit 20 to the oscillation wave generating circuit 10 according to the feedback signal, thereby controlling the oscillation wave generating circuit 10 to output a constant frequency signal.

[0030] The embodiment of the present application provides the ring-shaped oscillation circuit with feedback adjustment, that is, the oscillation wave generating circuit 10 is adjusted by the feedback frequency modulation circuit 20, so that the square wave frequency of the signal output by the oscillation wave generating circuit 10 does not change with process conditions and temperature.

[0031] Figure 3 It is a structural schematic diagram of an oscillator circuit for generating a constant output frequency signal, please refer to Figure 3 Preferably, the feedback frequency modulation circuit can comprise an error amplifier, a temperature-insensitive device and a switched-capacitor resistance circuit, wherein one end of the switched-capacitor resistance circuit is used as a first input end of the feedback frequency modulation circuit, the output end of the error amplifier is used as an output end of the feedback frequency modulation circuit, and the non-inverting terminal VN of the error amplifier is connected to a line between the switched-capacitor resistance circuit and the temperature-insensitive device.

[0032] Preferably, the temperature-insensitive device is a constant current source or a resistor.

[0033] The resistor used on the input circuit of the non-inverting terminal VN of the error amplifier is a temperature-insensitive resistor and cannot be a common resistor which changes greatly with temperature and process. For the inverting terminal VP of the error amplifier, a resistance voltage division form can be used, so that the input voltage of the inverting terminal VP can remain almost unchanged in different environments; and for the non-inverting terminal VN of the zero-crossing comparator, the resistance will be affected by environmental factors to change the resistance value, but the resistance value of the switched-capacitor resistance is almost not affected. In the case of resistance change, the oscillation frequency of the supply voltage output by the error amplifier in the steady state will also change, which makes the oscillation frequency of the output signal of the oscillation wave generating circuit have a certain error with the set value.

[0034] The input voltage of the inverting terminal VP of the error amplifier of the feedback frequency modulation circuit can be used as a reference voltage, and the input voltage of the non-inverting terminal VN is the voltage generated by the current flowing through the equivalent resistance of the switched-capacitor resistance circuit (and the temperature-insensitive device); after comparison and processing, the supply voltage (i.e. control voltage) of the oscillation wave generating circuit is generated, so as to realize the adjustment of the output signal frequency of the oscillation wave generating circuit.

[0035] The input voltage of the non-inverting terminal VN generates the voltage through the switched-capacitor resistance circuit structure and the temperature-insensitive device. The temperature-insensitive device can be a constant current source or a resistor. The input signal of the switched-capacitor resistance circuit is an oscillation wave with frequency information (i.e. the feedback signal of the feedback of the oscillation wave generating circuit output). With the change of the frequency of the oscillation wave, the switched-capacitor resistance circuit will generate different equivalent resistances, and after the temperature-insensitive device and the switched-capacitor circuit are divided, the supply voltage of the oscillation wave generating circuit is generated.

[0036] The comparison voltage generated by the error amplifier controls the ring oscillator in the oscillation wave generating circuit, thereby forming negative feedback. The process of negative feedback is, for example, as follows: when the supply voltage of the oscillation wave generating circuit is small, the frequency of the oscillation wave generated by the oscillation wave generating circuit is too low, the equivalent resistance of the switched capacitor resistance circuit is increased (the equivalent resistance R = 1 / fC, the equivalent resistance value will be described in detail below, and will not be described here), which can cause the supply voltage to rise, and ultimately can make the frequency of the output signal of the oscillation wave generating circuit stable at the set value.

[0037] Preferably, the supply voltage of the oscillation wave generating circuit output by the feedback frequency modulation circuit according to the feedback signal can be adjusted, thereby controlling the oscillation wave generating circuit to output a constant frequency signal, which can include: when the input voltage of the non-inverting terminal VN of the error amplifier is less than the input voltage of the inverting terminal VP of the error amplifier, the supply voltage output by the error amplifier is reduced, and the frequency of the feedback signal output by the oscillation wave generating circuit is reduced, wherein the input voltage of the non-inverting terminal VN is the product of the equivalent resistance of the switched capacitor resistance circuit and the current of the constant current source; the equivalent resistance of the switched capacitor resistance circuit is increased, the input voltage of the non-inverting terminal VN of the error amplifier is increased, thereby keeping the input voltage of the non-inverting terminal VN and the input voltage of the inverting terminal VP equal, and the oscillation wave generating circuit outputs a constant frequency signal.

[0038] For example, when the product of the equivalent resistance of the switched capacitor resistance circuit in the non-inverting terminal VN and the current of the constant current source is less than the reference voltage of the inverting terminal VP, the output voltage of the comparator is reduced, i.e. the supply voltage of the oscillation wave generating circuit is reduced, which ultimately leads to a decrease in the frequency of the oscillation wave output by the oscillation wave generating circuit, and at this time the equivalent resistance of the switched capacitor resistance circuit is increased (the equivalent resistance R = 1 / fC, the equivalent resistance value will be described in detail below, and will not be described here), so that the input voltage of the non-inverting terminal VN is increased, and ultimately the voltages of the non-inverting terminal VN and the inverting terminal VP of the comparator are kept equal, and the frequency of the output oscillator is also kept relatively constant.

[0039] Figure 4 is a schematic diagram of an example switched capacitor resistance circuit and a temperature insensitive device voltage divider, please refer to Figure 4 The switched capacitor resistance circuit can include a PMOS, an NMOS, a first capacitor and a second capacitor, a line between the gate of the PMOS and the gate of the NMOS as one end of the switched capacitor resistance circuit, a line between the source of the PMOS and the source of the NMOS connecting one end of the first capacitor, the other end of the first capacitor being grounded, a line between the drain of the PMOS and the drain of the NMOS connecting one end of the second capacitor, and the other end of the second capacitor being grounded.

[0040] For example, the input waveform of the switched capacitor resistor circuit is an oscillation wave with frequency information (i.e. the feedback signal output by the oscillation wave generation circuit as feedback). When the input waveform jumps between high and low levels, the corresponding amount of charge is stored on the capacitor. If the frequency of the square wave is f and the period is T, the average current from the source of the PMOS to the source of the NMOS is I = ΔQ / T = CV*f, and the equivalent resistance is Reff = V / I = 1 / fC. Accordingly, the equivalent resistance and a temperature-insensitive device (e.g. a temperature-insensitive resistor) are divided, and the output is used as the supply voltage of the oscillation wave generation circuit.

[0041] Please refer to Figure 3 Preferably, the oscillator circuit for generating a constant output frequency signal can further comprise a spread spectrum module, an input terminal of which is connected to a constant power supply, an output terminal of which is connected to the inverting input terminal VP of the error amplifier, and an output terminal of the oscillation wave generation circuit is connected to the clock control terminal of the spread spectrum module. The spread spectrum module outputs a spread spectrum signal as the input voltage of the inverting terminal VP of the error amplifier, so as to reduce electromagnetic interference.

[0042] In high-speed chip system design, high-frequency transmission signals, circuit pins and various loops on the PCB can cause greater electromagnetic radiation interference. Therefore, the input voltage of the inverting terminal VP of the error amplifier in the embodiment of the present application can not be a constant voltage (i.e. a reference voltage), but can be a step signal that varies around the required reference voltage. In this way, when the oscillation wave generation circuit outputs a constant frequency signal, a clock signal with a fixed frequency that periodically changes can be generated, thereby reducing electromagnetic interference through the clock signal that periodically changes. Therefore, the spread spectrum module in the embodiment of the present application outputs a periodic constant code signal through the state machine circuit thereof, and the code signal can control the opening and closing of the switches in the resistor divider network, thereby generating a step signal that periodically changes.

[0043] Figure 5 The structure of the example spread spectrum module is shown in the structural schematic diagram Figure 5 Preferably, the spread spectrum module can comprise a state machine circuit and a divider resistor circuit, wherein the input terminal of the state machine circuit is the clock control terminal of the spread spectrum module, the number of output terminals of the state machine circuit is one or more, and the number of divider resistor circuits is one or more, and each output terminal of the state machine circuit is respectively connected to one divider resistor circuit.

[0044] For example, the opening and closing of the switches of the divider resistor circuit can be controlled through the state machine circuit, thereby changing the size of the resistance value of the access circuit, so that the input voltage of the inverting terminal VP of the error amplifier is a step signal, thereby reducing the electromagnetic interference of the circuit. ​

[0045] Figure 6 is a structural schematic diagram of an example oscillation wave generating circuit, please refer to Figure 6 Preferably, the oscillation wave generating circuit comprises a ring oscillator and a shaping circuit, wherein an output terminal of the ring oscillator is connected to an input terminal of the shaping circuit, and an output terminal of the shaping circuit is an output terminal of the oscillator circuit for generating a constant output frequency signal.

[0046] Further preferably, the shaping circuit can comprise a filter and a buffer connected in sequence, wherein the filter comprises a capacitor and a first inverter connected in parallel, and the buffer comprises two second inverters connected in series.

[0047] By way of example, the ring oscillator of the oscillation wave generating circuit can generate an oscillation waveform through an odd number of inverters, output the oscillation waveform as a feedback signal of a feedback frequency modulation circuit, and the feedback frequency modulation circuit outputs a supply voltage of the ring oscillator according to the feedback signal to adjust the oscillation frequency of the ring oscillator, so as to finally ensure that the oscillator generates an oscillation wave of a required frequency. The oscillation waveform generated in this way only contains frequency information, and needs to be shaped. After the oscillation wave passes through the filter and the buffer, the oscillation wave can be shaped into a relatively standard square wave signal.

[0048] The embodiment of the present application provides a ring oscillator circuit with feedback adjustment capable of generating a stable output frequency, and the square wave frequency output by the ring oscillator circuit does not change with process conditions and temperature. Meanwhile, the spread spectrum technology is adopted to realize lower electromagnetic interference, higher signal accuracy and smaller power consumption.

[0049] The embodiment of the present application further provides a chip, which comprises a clock module, and the clock module comprises the oscillator circuit for generating a constant output frequency signal.

[0050] The oscillator circuit of the embodiment of the present application can be used in different clock modules, can ensure that the oscillator circuit can output a signal with almost constant frequency under different process conditions, realizes relatively accurate stable clock control, and can reduce power consumption and improve the overall performance of a chip system.

[0051] It should be further noted that the terms “comprising”, “containing” or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices including a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the statement “comprising a” does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0052] The above merely provides an example of the present application, and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall fall into the scope of claims of the present application.

Claims

1. An oscillator circuit for generating a constant output frequency signal, characterized by The oscillator circuit for generating constant output frequency signal comprises an oscillation wave generating circuit and a feedback frequency modulation circuit, wherein a first input end of the feedback frequency modulation circuit is connected to an output end of the oscillation wave generating circuit, and an output end of the feedback frequency modulation circuit is connected to a voltage control end of the oscillation wave generating circuit, The feedback frequency modulation circuit receives the output of the oscillation wave generating circuit as a feedback signal, and adjusts the supply voltage output by the feedback frequency modulation circuit to the oscillation wave generating circuit according to the feedback signal, thereby controlling the oscillation wave generating circuit to output a constant frequency signal. The feedback frequency modulation circuit comprises an error amplifier, a temperature insensitive device and a switched capacitor resistance circuit, wherein one end of the switched capacitor resistance circuit is a first input end of the feedback frequency modulation circuit, the output end of the error amplifier is an output end of the feedback frequency modulation circuit, the non-inverting input end VN of the error amplifier is connected to a line between the switched capacitor resistance circuit and the temperature insensitive device; The oscillation wave generating circuit comprises a ring oscillator and a shaping circuit, wherein an output end of the ring oscillator is connected to an input end of the shaping circuit, and the output end of the shaping circuit is an output end of the oscillator circuit for generating constant output frequency signal.

2. The oscillator circuit for generating a constant output frequency signal according to claim 1, characterized in that, The feedback frequency modulation circuit receives the output of the oscillation wave generating circuit as a feedback signal, and adjusts the supply voltage output by the feedback frequency modulation circuit to the oscillation wave generating circuit according to the feedback signal, thereby controlling the oscillation wave generating circuit to output a constant frequency signal. When the input voltage of the non-inverting input end VN of the error amplifier is less than the input voltage of the inverting input end VP of the error amplifier, the supply voltage output by the error amplifier decreases, and the frequency of the feedback signal output by the oscillation wave generating circuit decreases, wherein the input voltage of the non-inverting input end VN is the product of the equivalent resistance of the switched capacitor resistance circuit and the current of the constant current source; The equivalent resistance of the switched capacitor resistance circuit increases, the input voltage of the non-inverting input end VN of the error amplifier increases, and thus the input voltage of the non-inverting input end VN and the input voltage of the inverting input end VP remain equal, and the oscillation wave generating circuit outputs a constant frequency signal.

3. An oscillator circuit for generating a constant output frequency signal as claimed in claim 1 or 2, characterized in that, The switched capacitor resistance circuit comprises a PMOS, an NMOS, a first capacitor and a second capacitor, a line between the gate of the PMOS and the gate of the NMOS is one end of the switched capacitor resistance circuit, a line between the source of the PMOS and the source of the NMOS is connected to one end of the first capacitor, and the other end of the first capacitor is grounded, a line between the drain of the PMOS and the drain of the NMOS is connected to one end of the second capacitor, and the other end of the second capacitor is grounded.

4. The oscillator circuit for generating a constant output frequency signal according to claim 1, wherein, The temperature insensitive device is a constant current source or a resistor.

5. The oscillator circuit for generating a constant output frequency signal according to claim 1, wherein, The oscillator circuit for generating constant output frequency signal further comprises: a spread spectrum module, an input end of which is connected to a constant power supply, an output end of which is connected to the inverting input end VP of the error amplifier, and an output end of the oscillation wave generating circuit is connected to a clock control end of the spread spectrum module, The spread spectrum module outputs a spread spectrum signal as an input voltage of an inverting terminal VP of the error amplifier to reduce electromagnetic interference.

6. The oscillator circuit for generating a constant output frequency signal according to claim 5, wherein, The spread spectrum module comprises a state machine circuit and a voltage dividing resistor circuit, wherein an input terminal of the state machine circuit is a clock control terminal of the spread spectrum module, the number of output terminals of the state machine circuit is one or more, and the number of voltage dividing resistor circuits is one or more, and each output terminal of the state machine circuit is connected to one voltage dividing resistor circuit.

7. The oscillator circuit for generating a constant output frequency signal according to claim 1, wherein, The shaping circuit comprises a filter and a buffer connected in sequence, wherein the filter comprises a capacitor and a first inverter connected in parallel, the buffer comprises two second inverters connected in series.

8. A chip, characterized by The chip comprises a clock module, and the clock module comprises the oscillator circuit for generating a constant output frequency signal according to any one of claims 1-7.

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