Quickly-started low-power-consumption crystal oscillator

Abstract

The utility model discloses a quick-start low-power-consumption crystal oscillator, which comprises a low-power-consumption crystal oscillator, and the low-power-consumption crystal oscillator comprises a CMOS (complementary metal oxide semiconductor) inverter consisting of a PMOS (P-channel metal oxide semiconductor) and an NMOS (N-channel metal oxide semiconductor), a first capacitor connected to the input end of the CMOS inverter, and a second capacitor connected to the output end of the CMOS inverter, the resistor and the quartz crystal are connected with the input end and the output end of the CMOS inverter in parallel, the stable reference voltage circuit is connected between the power supply voltage VDD and the PMOS in series, the starting resistor is connected between the power supply voltage VDD and the output end of the CMOS inverter in series, and by increasing series connection between the starting resistor and the output end Vout of the CMOS inverter, the starting speed of the crystal oscillator is remarkably increased. By adding the starting resistor, the threshold voltage of an NMOS (N-channel metal oxide semiconductor) is improved at the initial starting stage of the oscillator, the process that the oscillator reaches a stable oscillation state is accelerated, and the starting time is shortened, which is particularly critical to application scenes needing quick response.

Description

Technical Field

[0001] The utility model belongs to the related technical field, and particularly relates to a low-power crystal oscillator with fast startup. Background Art

[0002] A crystal oscillator utilizes the piezoelectric effect of a crystal. The crystal serves as a control element for the oscillator frequency to obtain a relatively stable oscillation frequency. A crystal oscillator is composed of a crystal and various components such as transistors, resistors, and capacitors. For example, a crystal oscillator includes an inverter-type crystal oscillator using CMOS inverter elements.

[0003] The working mode of a traditional crystal oscillator is as follows: when powered by a power supply voltage, the initial charging voltages of the first and second capacitors are V, the PMOS is turned on, and the NMOS is not turned on. After the PMOS is turned on, the second capacitor is charged through the PMOS, and the first capacitor is charged through a resistor. When the voltage of the first capacitor exceeds a certain voltage, the NMOS will be turned on. The PMOS is cut off, the second capacitor discharges through the NMOS, and the first capacitor discharges through the resistor. When the voltage of the first capacitor drops below a certain voltage, the above actions are repeated again. Therefore, the traditional crystal oscillator operates at an oscillation frequency determined by the resistor, the crystal, and the capacitor. The traditional crystal oscillator also adds a switch. The startup resistor is connected in parallel with the input and output terminals Vin and Vout of the CMOS inverter and the resistor, which can accelerate the charging time of the first capacitor, continue to accelerate the operation of the inverter, reduce the startup time, and accelerate the oscillation startup process. The switch is closed at the initial stage of oscillation startup, so that the startup resistor between the input and output terminals Vin and Vout of the CMOS inverter plays a role in the circuit, and the connection is controlled to be disconnected after the normal operation starts.

[0004] Although the traditional inverter-type transistor oscillator provides high-speed and stable oscillation startup, the power consumption also increases with the square of the power supply voltage. Therefore, there is a problem that the power consumption increases when the power supply voltage increases. For this reason, we have invented a low-power crystal oscillator. By supplying power to the PMOS with a stable reference voltage, it can ensure operation at low power consumption. And by connecting a startup resistor in series between the power supply voltage and the output terminal of the CMOS inverter, it can start working quickly. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a low-power crystal oscillator with fast startup to solve the problem in the above background art that the traditional inverter-type transistor oscillator provides high-speed and stable oscillation startup, but the power consumption increases with the square of the power supply voltage. Therefore, if the power supply voltage increases, the power consumption also increases.

[0006] To achieve the above purpose, the utility model provides the following technical solution: a low-power crystal oscillator with fast startup, including a low-power crystal oscillator;

[0007] The low-power crystal oscillator includes:

[0008] A CMOS inverter composed of a PMOS and an NMOS;

[0009] A first capacitor connected to the input end of the CMOS inverter;

[0010] A second capacitor connected to the output end of the CMOS inverter;

[0011] A resistor and a quartz crystal connected in parallel with the input and output ends of the CMOS inverter;

[0012] A stable reference voltage circuit connected in series between the power supply voltage and the PMOS;

[0013] A starting resistor connected in series between the power supply voltage and the output end of the CMOS inverter.

[0014] Preferably, a switch connected between the starting resistor and the output end of the CMOS inverter.

[0015] Preferably, the switch is used to control the connection between the starting resistor and the output end of the CMOS inverter.

[0016] Preferably, the stable reference voltage circuit is used to be connected in series with the PMOS to provide a stable voltage.

[0017] Preferably, the starting resistor is connected between the power supply voltage and the output end of the CMOS inverter.

[0018] Preferably, the switch is in a closed state at the initial stage of startup.

[0019] Compared with the prior art, the present utility model provides a low-power crystal oscillator with fast startup, having the following beneficial effects:

[0020] In this low-power quartz A oscillator with fast startup, the following benefits can be achieved:

[0021] Improve startup speed and efficiency

[0022] Fast startup characteristic: By increasing the series connection between the starting resistor and the output Vout of the CMOS inverter, the present invention significantly improves the startup speed of the crystal oscillator. The addition of the starting resistor increases the threshold voltage of the NMOS at the initial stage of oscillator startup, accelerates the process of the oscillator reaching a stable oscillation state, and shortens the startup time, which is particularly crucial for application scenarios that require fast response.

[0023] Maintain low-power operation

[0024] Application of the stable reference voltage circuit: When the power supply voltage changes, the stable reference voltage circuit ensures that the reference voltage Vreg received by the PMOS remains constant, effectively controlling power consumption. Even when the power supply voltage fluctuates, the oscillator can operate in a low-power state, which is extremely important for battery-powered or power-sensitive devices.

[0025] Dynamic power management

[0026] Intelligent control of the switch: At the initial stage of oscillator startup, the switch is closed, and the startup resistor participates in the circuit operation to accelerate the startup process; once the oscillation is stable, the switch is opened to reduce unnecessary power consumption. This dynamic power management strategy ensures a fast startup while avoiding the additional power consumption caused by the startup resistor during stable operation, achieving a balance between efficiency and energy saving.

[0027] Improve oscillation stability and reliability

[0028] Enhance the threshold control of NMOS: The startup resistor increases the NMOS threshold during the startup stage, which not only speeds up the startup but also enhances the stability of the oscillator. This design avoids the problem of increased oscillation frequency caused by changes in output impedance during startup, improving the overall reliability and performance of the oscillator.

[0029] Adaptability and flexibility

[0030] Adapt to power supply voltage fluctuations: Through the combined design of the stable reference voltage circuit and the startup resistor, the low-power crystal oscillator of the present invention can adapt to changes in the power supply voltage and maintain stable operating performance and low-power characteristics.

[0031] In summary, through a series of carefully designed circuit components and control strategies, the present invention achieves the dual goals of fast startup and low-power operation, while maintaining the stability and reliability of the oscillator, providing an ideal solution for applications that require high-speed response and low energy consumption. Brief description of the drawings

[0032] Figure 1 It is a circuit diagram of a conventional inverter crystal oscillator for reference.

[0033] Figure 2 It is a circuit diagram of the fast-start low-power crystal oscillator in the present utility model.

[0034] Figure 3 It is an initial working waveform diagram of the inverter crystal oscillator in the present utility model.

[0035] Wherein:

[0036] Figure 1It includes: 100, a traditional inverter-type crystal oscillator; 110, a crystal; 120, a CMOS inverter; 131, a first capacitor; 132, a second capacitor; 140, a resistor; VDD, a power supply voltage; 121, a PMOS; 122, an NMOS; Vin, an input terminal; Vout, an output terminal; 150, a starting resistor; 160, a switch.

[0037] Figure 2 It includes: 200, a low-power crystal oscillator; 220, a CMOS inverter; 222, an NMOS; 232, a second capacitor; VDD, a power supply voltage; 260, a starting resistor; 210, a crystal; 221, a PMOS; 231, a first capacitor; 240, a resistor; 250, a stable reference voltage; 270, a switch. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0039] The present invention provides a Figures 1 - 3 fast-starting low-power crystal oscillator as shown, including a low-power crystal oscillator 200;

[0040] The low-power crystal oscillator 200 includes:

[0041] A CMOS inverter 220 composed of a PMOS 221 and an NMOS 222;

[0042] A first capacitor 231 connected to the input terminal of the CMOS inverter 220;

[0043] A second capacitor 232 connected to the output terminal of the CMOS inverter 220;

[0044] A resistor 240 and a quartz crystal 210 connected in parallel with the input and output terminals of the CMOS inverter 220;

[0045] A stable reference voltage 250 circuit connected in series between the power supply voltage VDD and the PMOS 221;

[0046] A starting resistor 260 connected in series between the power supply voltage VDD and the output terminal of the CMOS inverter 220.

[0047] Refer to Figure 1: It shows a traditional inverter-type crystal oscillator. The traditional inverter-type crystal oscillator 100 consists of a crystal 110, a CMOS inverter 120, a first capacitor 131, a second capacitor 132, a resistor 140, and a power supply voltage VDD.

[0048] The CMOS inverter 120 is composed of a PMOS 121 and an NMOS 122, and is connected in parallel with the crystal oscillator 110 between the input and output terminals Vin and Vout, serving to offset the amplitude reduction caused by the internal equivalent resistance of the crystal 110.

[0049] The first capacitor 131 is connected to the input terminal Vin of the CMOS inverter 120, and the other end of the capacitor is grounded.

[0050] The second capacitor 132 is connected to the output terminal Vout of the CMOS inverter 120, and the other end of the capacitor is grounded. The traditional crystal oscillator 100 adjusts the oscillator frequency according to the charge and discharge of the capacitors 131 and 132 and the designed frequency of the crystal 110.

[0051] The resistor 140 is connected in parallel with the input and output terminals Vin and Vout of the CMOS inverter 120, determining the operating point of the CMOS inverter 120. The power supply voltage VDD is connected to the PMOS 121 to provide a reference voltage.

[0052] The working mode of the traditional crystal oscillator 100 is as follows: when the power supply voltage VDD supplies power, the initial charging voltages of the first and second capacitors 131 and 132 are 0V, the PMOS 121 is turned on, and the NMOS 122 is not turned on. After the PMOS 121 is turned on, the second capacitor 132 is charged through the PMOS 121, and the first capacitor 131 is charged through the resistor 140. When the voltage of the first capacitor 131 exceeds a certain voltage, the NMOS 122 will be turned on. The PMOS 121 is cut off, the second capacitor 132 discharges through the NMOS 122, and the first capacitor 131 discharges through the resistor 140. When the voltage of the first capacitor 131 drops below a certain voltage, the above actions are repeated again.

[0053] Therefore, the traditional crystal oscillator 100 operates at an oscillation frequency determined by the resistor 140, the crystal 110, and the capacitors 131 and 132. The traditional crystal oscillator 100 also adds a switch 160. A starting resistor 150 is connected in parallel with the input and output terminals Vin and Vout of the CMOS inverter and the resistor 140, which can accelerate the charging time of the first capacitor 131, continue to accelerate the operation of the inverter 120, reduce the starting time, and accelerate the starting oscillation process. The switch 160 is closed at the initial stage of starting oscillation, enabling the starting resistor 150 to act in the circuit between the input and output terminals Vin and Vout of the CMOS inverter, and controlling the disconnection after the normal operation starts.

[0054] Although the traditional inverter transistor oscillator 100 provides high-speed start-up and stable start-up, referring to Formula 1, the power consumption increases with the square of the power supply voltage. Therefore, if the power supply voltage increases, the power consumption will also increase.

[0055] Formula 1 Power consumption = f·C·VDD2

[0056] Where f is the operating frequency, C is the equivalent capacitance at the output terminal, and VDD is the power supply voltage.

[0057] Reference Figures 2 - 3 : In this embodiment, the usage steps and working principle

[0058] Usage steps

[0059] Power supply and initialization:

[0060] Connect the power supply voltage VDD to the circuit, and the stable reference voltage circuit 250 starts to work, providing a stable reference voltage Vreg for PMOS221.

[0061] The first capacitor 231 and the second capacitor 232 are in an uncharged state, and the voltage is 0V.

[0062] Startup phase:

[0063] The switch 270 is closed, and the startup resistor 260 is connected in series with the output terminal Vout of the CMOS inverter 220.

[0064] PMOS221 is turned on, and starts to charge the second capacitor 232 through the power supply voltage VDD.

[0065] The first capacitor 231 is charged through the resistor 240.

[0066] The startup resistor 260 accelerates the startup process of the CMOS inverter 220, increases the threshold of NMOS222, and speeds up the startup of oscillation.

[0067] Oscillation startup:

[0068] When the voltage of the first capacitor 231 rises to a certain value, NMOS222 starts to conduct.

[0069] The CMOS inverter 220 starts to oscillate, and the oscillation frequency is determined by the characteristics of the crystal 210.

[0070] Stable operation phase:

[0071] Once the oscillation is stable, the switch 270 is disconnected, and the startup resistor 260 is removed from the circuit.

[0072] The circuit continues to work in a low-power state, and the stable reference voltage circuit 250 ensures that the power consumption does not change with the change of the power supply voltage VDD.

[0073] Working principle

[0074] In the low-power crystal oscillator 200 with fast startup, the circuit achieves fast startup and low power consumption through the following key components:

[0075] Stable reference voltage circuit 250: Ensures that PMOS221 can still provide a stable bias voltage when the power supply voltage changes, keeping the power consumption stable.

[0076] Startup resistor 260 and switch 270: The startup resistor increases the threshold voltage of NMOS222 at the initial stage of startup, accelerating the startup process of the oscillator. The switch is used to control the connection of the startup resistor and disconnects after the oscillation is stable to reduce power consumption.

[0077] Crystal 210 and CMOS inverter 220: The crystal provides frequency control, and the CMOS inverter, as the core of the oscillator, amplifies and flips the signal.

[0078] Resistor 240 and capacitors 231, 232: Act together to regulate and stabilize the frequency of the oscillator. The resistor determines the operating point of the CMOS inverter, and the charging and discharging processes of the capacitors drive the oscillator to work.

[0079] Through the above design, the low-power crystal oscillator 200 with fast startup ensures fast startup while maintaining low power consumption, making it suitable for low-power application environments.

[0080] As Figures 2 - 3 shown, the switch 270 is connected between the startup resistor 260 and the output terminal of the CMOS inverter 220. The switch 270 is used to control the connection between the startup resistor 260 and the output terminal of the CMOS inverter 220. The stable reference voltage 250 circuit is used to be connected in series with PMOS221 to provide a stable voltage. The startup resistor 260 is connected between the power supply voltage VDD and the output terminal of the CMOS inverter 220, and the switch 270 is in the closed state at the initial stage of startup.

[0081] Preferably, the fast startup principle

[0082] The realization of fast startup depends on the addition of the startup resistor 260, which is connected in series with the output terminal Vout of the CMOS inverter. At the initial stage of oscillator startup, this resistor increases the threshold voltage of NMOS222, helping to quickly overcome the turn-on threshold of NMOS, thus accelerating the startup process of the oscillator. Once the oscillator starts up stably, the startup resistor no longer participates in the operation to reduce power consumption.

[0083] Low-power working principle

[0084] The realization of low power consumption benefits from the design of the stable reference voltage circuit 250, which ensures that PMOS 221 can still provide a stable bias voltage when the power supply voltage changes. This design reduces the impact of power supply voltage fluctuations on the oscillator performance, thus maintaining a low power consumption level. In addition, the use of switch 270 allows for providing an additional current path during the startup phase to improve the startup speed of NMOS, and this path is closed after stable operation to further optimize the power consumption.

[0085] Specific steps

[0086] Power supply: Connect the power supply voltage VDD to the circuit to provide the initial operating voltage for the oscillator.

[0087] Function of startup resistor: At the initial stage of oscillator startup, the startup resistor 260 is connected in series with the output terminal Vout of the CMOS inverter to help start the oscillator quickly.

[0088] Provision of stable reference voltage: The stable reference voltage circuit 250 provides a stable bias voltage for PMOS 221 to ensure that the oscillator can still operate stably when the power supply voltage fluctuates.

[0089] Switch control: The switch 270 is closed at the initial startup stage to accelerate the startup process and is opened after the oscillation is stable to reduce the power consumption.

[0090] Oscillation stability: After the oscillator starts up, the startup resistor no longer participates in the operation, and the oscillator continues to operate at a stable frequency and with low power consumption.

[0091] Through the above steps, the fast-start low-power quartz crystal oscillator of the present invention can achieve fast startup while maintaining high efficiency, and is applicable to application scenarios with strict requirements for startup time and power consumption.

[0092] Finally, it should be noted that the above are only the preferred embodiments of the present utility model and are not used to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A fast-starting and low-power crystal oscillator, characterized in that: Comprises a low-power crystal oscillator (200); The low-power crystal oscillator (200) includes: A CMOS inverter (220) composed of a PMOS (221) and an NMOS (222); A first capacitor (231) connected to the input end of the CMOS inverter (220); A second capacitor (232) connected to the output end of the CMOS inverter (220); A resistor (240) and a quartz crystal (210) connected in parallel with the input and output ends of the CMOS inverter (220); A stable reference voltage (250) circuit connected in series between the power supply voltage (VDD) and the PMOS (221); A startup resistor (260) connected in series between the power supply voltage (VDD) and the output end of the CMOS inverter (220).

2. The fast-start low-power crystal oscillator according to claim 1, characterized in that: A switch (270) connected between the startup resistor (260) and the output end of the CMOS inverter (220).

3. A fast-starting low-power crystal oscillator according to claim 2, characterized in that: The switch (270) is used to control the connection between the startup resistor (260) and the output end of the CMOS inverter (220).

4. A fast-starting low-power crystal oscillator according to claim 1, characterized in that: The stable reference voltage (250) circuit is used to be connected in series with the PMOS (221) to provide a stable voltage.

5. A fast-start low-power crystal oscillator according to claim 1, characterized in that: The startup resistor (260) is connected between the power supply voltage (VDD) and the output end of the CMOS inverter (220).

6. A fast-starting low-power crystal oscillator according to claim 2, characterized in that: The switch (270) is in a closed state at the initial stage of startup.

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