Crystal oscillator control device

Abstract

This application discloses a crystal oscillator control device, comprising: a differential amplifier, with a first input voltage of a reference voltage, a second input connected to a first terminal of the crystal oscillator, and an output connected to a second terminal of the crystal oscillator; an input of a self-biasing control module connected to the output of the crystal oscillator; and an output of the self-biasing control module connected to the bias terminal of the differential amplifier. When the crystal oscillator is in the oscillation state, the voltage amplitude at the output of the differential amplifier increases from a first voltage value to a second voltage value, the bias current provided by the self-biasing control module decreases from a first current value to a second current value, and the gain of the differential amplifier is greater than a preset gain. When the crystal oscillator is in the resonance state, the voltage amplitude at the output of the differential amplifier remains at the second voltage value, the bias current remains at the second current value, and the gain of the differential amplifier decreases to the preset gain value. This solution achieves rapid crystal oscillation start-up and reduces power consumption during operation.

Description

Technical Field

[0001] This application relates to the field of integrated circuit technology, and in particular to a crystal oscillator control device. Background Technology

[0002] When a crystal oscillator circuit is initially powered on and begins oscillation, a relatively high oscillation gain is required to ensure a fast start-up speed. Using the minimum gain often results in a slow start-up speed, leading to a significant power-on delay and low sensitivity. This drawback is particularly pronounced in circuits requiring rapid response. However, simply increasing the gain of the crystal oscillator circuit to improve start-up speed is problematic. Since the gain of existing crystal oscillators is fixed, this high gain must be maintained after start-up and during normal operation, resulting in excessive power consumption. This approach is impractical for circuits using dry batteries and requiring extended operation (e.g., battery-powered perpetual calendars, portable communication devices, and digital energy meters). Therefore, resolving the conflict between reducing power consumption and accelerating start-up speed has become a pressing issue in the field of crystal oscillator circuits. Summary of the Invention

[0003] The purpose of this application is to provide a crystal oscillator control device, thereby resolving the contradiction between reducing circuit power consumption and accelerating oscillation speed in the prior art.

[0004] To achieve the above objectives, this application provides a crystal oscillator control device, comprising:

[0005] The differential amplifier has a first input voltage that is a reference voltage, a second input terminal that is connected to the first terminal of a crystal oscillator, and an output terminal that is connected to the second terminal of the crystal oscillator.

[0006] A self-biasing control module, wherein the input terminal of the self-biasing control module is connected to the output terminal of the crystal oscillator; and the output terminal of the self-biasing control module is connected to the bias terminal of the differential amplifier.

[0007] When the crystal oscillator is in the oscillation state, the voltage amplitude at the output terminal of the differential amplifier increases from a first voltage value to a second voltage value, the bias current provided by the self-bias control module to the differential amplifier decreases from a first current value to a second current value, and the gain of the differential amplifier is greater than a preset gain.

[0008] When the crystal oscillator is in a resonant state, the voltage amplitude at the output of the differential amplifier is maintained at the second voltage value, the bias current is maintained at the second current value, and the gain of the differential amplifier (OP1) is reduced to the preset gain value.

[0009] Optionally, the self-biasing control module includes:

[0010] A voltage divider module, wherein the first end of the voltage divider module is connected to the output end of the differential amplifier, and the second end of the voltage divider module is connected to a DC power supply;

[0011] The self-biased current source has its input terminal connected to the voltage divider terminal of the voltage divider module, its output terminal connected to the bias terminal, and its power supply terminal connected to the DC power supply.

[0012] The voltage divider module is used to divide the voltage output by the differential amplifier and provide the first voltage obtained by the voltage division to the self-biased current source.

[0013] The self-biased current source is used to adjust the bias current input to the bias terminal based on the first voltage.

[0014] Optionally, the voltage divider module includes: a first voltage divider element and a second voltage divider element connected in series between the output terminal of the differential amplifier and the DC power supply;

[0015] The connection point between the first voltage divider element and the second voltage divider element forms the voltage divider end of the voltage divider module.

[0016] Optionally, both the first voltage divider element and the second voltage divider element are capacitors, resistors, or field-effect transistors.

[0017] Optionally, the self-biased current source includes:

[0018] A cascaded mirror current source consisting of a first mirror current source and a second mirror current source;

[0019] A low-pass filter is connected between the gates of the two MOS transistors of the first mirror current source;

[0020] The voltage divider module is connected to the input terminal of the low-pass filter; the second mirror current source is connected to the bias terminal.

[0021] Optionally, the low-pass filter includes any of the following:

[0022] RC filter;

[0023] LC filter.

[0024] Optionally, the first mirror current source includes a first metal-oxide-semiconductor field-effect transistor (MOSFET), a second MOSFET, and a first resistor;

[0025] The second mirror current source includes a third MOSFET and a fourth MOSFET;

[0026] The first resistor is connected between the first terminal of the first MOSFET and the DC power supply.

[0027] The first terminal of the second MOSFET is connected to the DC power supply;

[0028] The gate of the first MOS transistor is connected to the output terminal of the low-pass filter;

[0029] The gate of the second MOS transistor, the input terminal of the low-pass filter, the second terminal of the second MOS transistor, and the first terminal of the fourth MOS transistor are all connected to the voltage divider terminal;

[0030] The second terminal of the first MOS transistor is connected to the first terminal of the third MOS transistor, the gate of the third MOS transistor, the gate of the fourth MOS transistor, and the bias terminal;

[0031] The second terminal of the third MOS transistor and the second terminal of the fourth MOS transistor are grounded;

[0032] Specifically, when the MOSFET is a PMOS transistor, the first terminal is the source and the second terminal is the drain; when the MOSFET is an NMOS transistor, the first terminal is the drain and the second terminal is the source.

[0033] Optionally, a fifth MOS transistor is connected between the self-biased current source and the bias terminal;

[0034] The gate of the fifth MOS transistor is connected to the self-biased current source, the first terminal of the fifth MOS transistor is connected to the bias terminal, and the second terminal of the fifth MOS transistor is grounded; wherein, when the fifth MOS transistor is a PMOS transistor, the first terminal is the source and the second terminal is the drain; when the fifth MOS transistor is an NMOS transistor, the first terminal is the drain and the second terminal is the source.

[0035] Optionally, the crystal oscillator control device further includes a feedback resistor connected in parallel with the crystal oscillator;

[0036] The resistance of the feedback resistor is NKΩ, where N is greater than or equal to 1 and less than 1000Ω.

[0037] Optionally, the crystal oscillator control device further includes:

[0038] A first load capacitor, the first end of which is connected to the first end of the crystal oscillator, and the second end of which is grounded;

[0039] The second load capacitor has its first terminal connected to the second terminal of the crystal oscillator and its second terminal grounded.

[0040] The driver is connected to the output of the differential amplifier.

[0041] The above-mentioned technical solution of this application has at least the following beneficial effects:

[0042] The crystal oscillator control device of this application embodiment includes: a differential amplifier, the input voltage of the first input terminal being a reference voltage, the second input terminal being connected to the first terminal of the crystal oscillator, and the output terminal of the differential amplifier being connected to the second terminal of the crystal oscillator; a self-biasing control module, the input terminal of the self-biasing control module being connected to the output terminal of the crystal oscillator; and the output terminal of the self-biasing control module being connected to the bias terminal of the differential amplifier. Thus, the bias current of the differential amplifier is adjusted based on the voltage generated by the crystal oscillation. Specifically, when the crystal oscillator is in the oscillation state, the voltage amplitude at the output terminal of the differential amplifier increases from a first voltage value to a second voltage value, the bias current provided by the self-biasing control module to the differential amplifier decreases from a first current value to a second current value, and the gain of the differential amplifier is greater than a preset gain. When the crystal oscillator is in the resonance state, the voltage amplitude at the output terminal of the differential amplifier remains at the second voltage value, the bias current remains at the second current value, and the gain of the differential amplifier decreases to the preset gain value. This allows for a larger bias current to be provided to the differential amplifier during crystal oscillation to increase its gain and achieve rapid oscillation. During crystal resonance, the bias current is automatically reduced to decrease its gain, thereby reducing overall power consumption and resolving the contradiction between the current crystal oscillation speed and circuit power consumption. Attached Figure Description

[0043] Figure 1 This is one of the schematic diagrams of a crystal oscillator control device according to an embodiment of this application;

[0044] Figure 2 This is a second schematic diagram of the crystal oscillator control device according to an embodiment of this application;

[0045] Figure 3 This is the third schematic diagram of the crystal oscillator control device according to an embodiment of this application;

[0046] Figure 4 This is the fourth schematic diagram of the crystal oscillator control device according to an embodiment of this application.

[0047] Explanation of reference numerals in the attached figures:

[0048] OP1 - Differential amplifier, X - Crystal oscillator, 200 - Self-bias control module, 210 - Voltage divider module, 220 - Self-bias current source, VDD - DC power supply, 221 - Low-pass filter, M1 - First MOSFET, M2 - Second MOSFET, M3 - Third MOSFET, M4 - Fourth MOSFET, M5 - Fifth MOSFET, M6 - Sixth MOSFET, M7 - Seventh MOSFET, R1 - First resistor, R0 - Feedback resistor, C11 - First load capacitor, C12 - Second load capacitor, 300 - Driver, Cn - First voltage divider capacitor, Cm - Second voltage divider capacitor. Detailed Implementation

[0049] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0051] The crystal oscillator control device provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0052] like Figure 1 The diagram shown is one of the schematic diagrams of a crystal oscillator control device according to an embodiment of this application. The crystal oscillator control device includes:

[0053] The differential amplifier OP1 has a first input voltage that is a reference voltage, a second input terminal that is connected to the first terminal of the crystal oscillator X, and an output terminal that is connected to the second terminal of the crystal oscillator X.

[0054] Self-biasing control module 200, the input terminal of which is connected to the output terminal of crystal oscillator X; the output terminal of self-biasing control module 200 is connected to the bias terminal of differential amplifier OP1;

[0055] When the crystal oscillator X is in the oscillation state, the voltage amplitude at the output terminal of the differential amplifier OP1 increases from a first voltage value to a second voltage value, the bias current provided by the self-bias control module 200 to the differential amplifier OP1 decreases from a first current value to a second current value, and the gain of the differential amplifier OP1 is greater than a preset gain.

[0056] When the crystal oscillator X is in a resonant state, the voltage amplitude at the output terminal of the differential amplifier OP1 is maintained at the second voltage value, the bias current is maintained at the second current value, and the gain of the differential amplifier OP1 is reduced to the preset gain value.

[0057] It should be noted that the differential amplifier OP1 is used to amplify the piezoelectric effect of crystal oscillator X, thereby gradually outputting a large-amplitude sine pulse. The sine pulse signal is driven by driver 300 to form a stable clock pulse. The preset gain can be 1, that is, during the oscillation process of crystal oscillator X, the gain of differential amplifier OP1 is large, so as to realize the rapid start-up of crystal oscillator. During the resonance process of crystal oscillator X, the gain of differential amplifier OP1 is reduced to 1, thus reducing the power consumption during normal operation of crystal oscillator.

[0058] Here, it should be noted that, as Figure 4 As shown, in this embodiment, a reference voltage can be provided to the differential amplifier OP1 via a reference circuit. Specifically, the reference circuit includes a sixth metal-oxide-semiconductor field-effect transistor (MOSFET), abbreviated as MOS transistor M6, and a seventh MOSFET M7. The first terminal of the sixth MOSFET M6 is connected to the DC power supply VDD, and the first terminal of the seventh MOSFET M7 is grounded. The second terminal and gate of the sixth MOSFET M6 are connected to the second terminal and gate of the seventh MOSFET, and are connected to the first input terminal of the differential amplifier OP1. Thus, the reference circuit provides a reference voltage to the differential amplifier OP1. When the sixth and seventh MOSFETs are PMOS transistors (P-channel MOSFETs), the first terminal is the source and the second terminal is the drain; when the sixth and seventh MOSFETs are NMOS transistors, the first terminal is the drain and the second terminal is the source.

[0059] It should also be noted that the first input terminal can be the non-inverting input terminal of the differential amplifier OP1, and the second input terminal can be the inverting input terminal of the differential amplifier OP2; of course, it can also be the opposite, that is: the first input terminal is the inverting input terminal of the differential amplifier OP1, and the second input terminal is the non-inverting input terminal of the differential amplifier OP1.

[0060] In addition, in this embodiment of the application, maintaining the first voltage value can be the voltage at the output terminal of the differential amplifier OP1 as the first voltage value, or maintaining it near the first voltage value, that is, relative error is allowed; similarly, maintaining the first current value can be the bias current as the first current value, or maintaining it near the first current value, that is, relative error is allowed.

[0061] In the crystal oscillator control device of this application embodiment, the input voltage of the first input terminal of the differential amplifier OP1 is a reference voltage, the second input terminal is connected to the first terminal of the crystal oscillator X, and the output terminal of the differential amplifier OP1 is connected to the second terminal of the crystal oscillator X; the input terminal of the self-bias control module 200 is connected to the output terminal of the crystal oscillator X; the output terminal of the self-bias control module 200 is connected to the bias terminal of the differential amplifier OP1; thus, by cooperating with the differential amplifier OP1 and the self-bias control module 200, the bias current of the differential amplifier OP1 can be adjusted based on the voltage generated by the crystal oscillator X, thereby adjusting the gain of the differential amplifier, and reducing the power consumption during crystal oscillator resonance while ensuring rapid crystal oscillation. Specifically, when the crystal oscillator X is in the oscillation state, the voltage amplitude at the output terminal of the differential amplifier OP1 increases from a first voltage value to a second voltage value, the bias current provided by the self-bias control module 200 to the differential amplifier OP1 decreases from a first current value to a second current value, and the gain of the differential amplifier OP1 is greater than a preset gain. When the crystal oscillator X is in the resonance state, the voltage amplitude at the output terminal of the differential amplifier OP1 remains at the second voltage value, the bias current remains at the second current value, and the gain of the differential amplifier OP1 decreases to the preset gain value. This solves the contradiction between power consumption and crystal oscillation speed in the prior art.

[0062] As an optional implementation, such as Figure 2 As shown, the self-biasing control module 200 includes:

[0063] Voltage divider module 210, the first end of which is connected to the output terminal of differential amplifier OP1, and the second end of which is connected to DC power supply VDD;

[0064] Self-biased current source 220, the input terminal of which is connected to the voltage divider terminal of the voltage divider module 210, the output terminal of which is connected to the bias terminal, and the power supply terminal of which is connected to the DC power supply VDD.

[0065] The voltage divider module 210 is used to divide the voltage output by the differential amplifier OP1 and provide the first voltage obtained by the voltage division to the self-biased current source 220.

[0066] The self-biased current source 220 is used to adjust the bias current input to the bias terminal based on the first voltage.

[0067] In this optional implementation, the voltage signal output by the differential amplifier OP1 is divided by the voltage divider module 210, and the first voltage obtained by the voltage divider is input to the self-biasing current source 220. The self-biasing current source 220 adjusts the bias current input to the differential amplifier OP1 based on the first voltage, thereby adjusting the gain of the differential amplifier OP1. In this way, the gain of the differential amplifier OP1 is related to its output voltage (the voltage generated by the crystal oscillator X). Thus, on the one hand, an external reference bias is not required, which further reduces the overall power consumption to a certain extent; on the other hand, complex control logic and programmable adjustment of the operating parameters of the differential amplifier OP1 are not required, which greatly reduces the complexity of the crystal oscillator control device and reduces the difficulty of use.

[0068] Here, it should be noted that the working principle of the self-biasing control module 200 is as follows: When crystal oscillator X first starts oscillating, the signal amplitude at the second terminal of crystal oscillator X (the signal at the output terminal of differential amplifier OP1) is extremely small. All the bias current in the oscillation circuit is generated by the self-biasing current source 220, and the current at this time is a fixed value, approximately 35μA. The overall current of the crystal oscillator control device is approximately 2mA. During the oscillation process, the signal amplitude at the second terminal of crystal oscillator X gradually increases. The signal at the second terminal is fed back to the self-biasing current source 220 through the voltage divider module 210. The self-biasing current source 220 gradually reduces the output bias current according to the voltage fed back by the voltage divider module 210, thereby reducing the overall power consumption of the crystal oscillator control circuit. This process is automatically adjustable. When the oscillation amplitude at the second terminal of crystal oscillator X increases to a level that makes the oscillation amplitude decrease, the self-biasing current source 220 gradually decreases the output bias current, thereby reducing the overall power consumption of the crystal oscillator control circuit. Figure 4 When the output clkout of the driver 300 is a square wave, the bias current output from the bias current source 220 decreases to make the gain of the differential amplifier OP1 1. At this time, the crystal oscillator X reaches balance and operates in a low-power state.

[0069] As a specific implementation method, such as Figure 4 As shown, the voltage divider module 210 includes: a first voltage divider element and a second voltage divider element connected in series between the output terminal of the differential amplifier OP1 and the DC power supply VDD;

[0070] The connection point between the first voltage divider element and the second voltage divider element forms the voltage divider end of the voltage divider module 210.

[0071] In this optional implementation, the voltage divider module 210 is constructed by using two voltage divider elements connected in series, which simplifies the structure of the voltage divider module 210, reduces the complexity of the crystal oscillator control device, and realizes automatic reduction of power consumption when the crystal oscillator X outputs a stable clock.

[0072] In a more specific implementation, both the first voltage divider element and the second voltage divider element are capacitors, resistors, or field-effect transistors.

[0073] It should be noted that, in this optional implementation, passive components are preferably used to construct the voltage divider module 210, so as to... Figure 4 For example, a voltage divider module 210 is constructed using a first voltage divider capacitor Cm and a second voltage divider capacitor Cn. In this way, on the one hand, the voltage divider module 210 does not consume additional power, further reducing the overall power consumption and complexity of the entire crystal oscillator control device; in particular, by reasonably configuring the voltage division ratio, the power consumption of crystal oscillator X after stabilization can be reduced by about 2 / 3 compared with the power consumption of crystal oscillator X when it starts oscillating; on the other hand, the layout matching degree can be better in the chip design process, so that the chip performance can be guaranteed.

[0074] Furthermore, as an optional implementation, such as Figure 3 As shown, the crystal oscillator control device also includes a feedback resistor R0 connected in parallel with the crystal oscillator X;

[0075] Wherein, the resistance value of the feedback resistor R0 is NKΩ, where N is greater than or equal to 1 and less than 1000.

[0076] In other words, with the crystal oscillator control device of this application embodiment, the feedback resistor R0 can be a fixed resistor in the kiloohm range. This can save the large feedback resistor of tens of megohms, which is beneficial to reduce the layout area and reduce the cost of the chip.

[0077] As a specific implementation method, such as Figure 4 As shown, the self-biased current source 220 includes:

[0078] A cascaded mirror current source consisting of a first mirror current source and a second mirror current source;

[0079] A low-pass filter 221 is connected between the gates of the two MOS transistors of the first mirror current source;

[0080] The voltage divider module 210 is connected to the input terminal of the low-pass filter 221; the second mirror current source is connected to the bias terminal.

[0081] In this specific implementation, the low-pass filter 221 is used to filter out the AC component of the output voltage at the output terminal of the differential amplifier OP1, thereby inputting the filtered DC component to the first mirror current source, so that the first mirror current source outputs current based on the DC component, thereby providing bias current to the differential amplifier OP1 through the second mirror current source.

[0082] As a more specific implementation, the low-pass filter 221 includes any of the following:

[0083] RC filter;

[0084] LC filter.

[0085] In this specific implementation, based on the principle of passive component voltage division and the use of RC or LC filters, there is no need for complex control logic and programmable adjustment, which greatly reduces the complexity of the crystal oscillator control device and the difficulty of use.

[0086] As another specific implementation method, such as Figure 4 As shown, the first mirror current source includes a first MOSFET M1, a second MOSFET M2, and a first resistor R1;

[0087] The second mirror current source includes a third MOSFET M3 and a fourth MOSFET M4;

[0088] Wherein, the first resistor R1 is connected between the first terminal of the first MOSFET M1 and the DC power supply VDD;

[0089] The first terminal of the second MOSFET M2 is connected to the DC power supply VDD;

[0090] The gate of the first MOS transistor M1 is connected to the output terminal of the low-pass filter 221;

[0091] The gate of the second MOS transistor M2, the input terminal of the low-pass filter 221, the second terminal of the second MOS transistor M2, and the first terminal of the fourth MOS transistor M4 are all connected to the voltage divider terminal;

[0092] The second terminal of the first MOS transistor (M1) is connected to the first terminal of the third MOS transistor (M3), the gate of the third MOS transistor (M3), the gate of the fourth MOS transistor (M4), and the bias terminal.

[0093] The second terminal of the third MOS transistor and the second terminal of the fourth MOS transistor M4 are grounded;

[0094] Specifically, when the MOSFET is a PMOS transistor, the first terminal is the source and the second terminal is the drain; when the MOSFET is an NMOS transistor, the first terminal is the drain and the second terminal is the source.

[0095] In this specific implementation, by connecting the gate of the first MOSFET M1 to the output of the low-pass filter 221, the DC component obtained after filtering by the low-pass filter 221 can be input to the gate of the first MOSFET M1. This causes the gate voltage of the first MOSFET M1 to change with the output signal of the differential amplifier OP1 (as the output signal of the differential amplifier OP1 increases, the gate voltage of the first MOSFET increases). As the gate voltage increases, the bias current output from the bias current source 220 gradually decreases, thereby reducing the overall power consumption of the crystal oscillator. When the oscillation amplitude at the second terminal of the crystal oscillator X increases to the point that the output clkout of the driver 300 is a square wave, the bias current from the bias current source 220 decreases to the point that the gain of the differential amplifier OP1 drops to 1, and the crystal oscillator X reaches equilibrium and operates in a low-power state.

[0096] It should be noted here that the current of the self-biased current source 220 is determined by the ratio of the difference between the gate voltage Vgs of the first MOSFET and the second MOSFET to the first resistor R1, as shown in the following formula:

[0097]

[0098] Among them, I R1 V is the output current. gs1 V is the gate voltage of the first MOSFET M1. gs2 R1 is the gate voltage of the second MOSFET M2, and R1 is the resistance value of the first resistor R1.

[0099] Furthermore, as an optional implementation, a fifth MOS transistor M5 is connected between the self-biased current source 220 and the bias terminal;

[0100] The gate of the fifth MOS transistor M5 is connected to the self-biased current source 220, the first terminal of the fifth MOS transistor M5 is connected to the bias terminal, and the second terminal of the fifth MOS transistor is grounded; wherein, when the fifth MOS transistor M5 is a PMOS transistor, the first terminal is the source and the second terminal is the drain; when the fifth MOS transistor M5 is an NMOS transistor, the first terminal is the drain and the second terminal is the source.

[0101] It should be noted that the third MOSFET M3 and the fourth MOSFET M4 are mirror images of each other. The fifth MOSFET M5 is the tail current of the differential amplifier OP1. In order to ensure that the resonant circuit can start oscillating, meet the "Barkhausen criterion", and be compatible with more crystals with different resonant frequencies, the bias current for starting oscillation is generally large. However, after the resonant circuit tends to stabilize, the requirement for bias current can be reduced.

[0102] It should also be noted that when crystal oscillator X first starts oscillating, the signal amplitude at the second terminal of crystal oscillator X is extremely small. However, during the oscillation process, the bias current is no longer determined by the difference between the gate voltages of the first MOSFET M1 and the second MOSFET M2 in the above formula. The amplitude of the sinusoidal pulse at the second terminal of crystal oscillator X gradually increases. After being divided by the voltage divider module 210, the pulse amplitude at the voltage divider terminal also increases accordingly. After passing through the low-pass filter 221, the high-frequency AC component is filtered out, and the DC component is retained. The voltage output by the low-pass filter 221 also slowly increases. At this time, the voltage output by the low-pass filter 221 controls the gate voltage of the first MOSFET M1, causing the bias current output by the bias current source 220 to gradually decrease, and the overall power consumption also decreases accordingly.

[0103] The voltage at the voltage divider terminal is calculated as follows:

[0104]

[0105] Among them, V x V is the voltage at the voltage divider terminals. xtal_out C is the voltage at the output of the differential amplifier OP1. n C is the capacitance of the first voltage divider capacitor. m This is the capacitance value of the second voltage divider capacitor.

[0106] As can be seen, as the voltage at the output of the differential amplifier OP1 increases, the voltage at the voltage divider also increases.

[0107] Simulation results show that during the start-up process, the voltage amplitude Vxtal_out at the output of the differential amplifier OP1 gradually increases, and the voltage Vx at the voltage divider and the gate voltage Vg of the first MOSFET also increase accordingly. The output current I of the first current mirror source... R1 As the clock gradually decreases, the reference current also stabilizes after the clock stabilizes. The reference current decreases from about 35uA to about 5uA. Simulation results show that the solution in this embodiment can automatically reduce the power consumption of the crystal oscillator.

[0108] As an optional implementation, such as Figure 4 As shown, the crystal oscillator control device further includes:

[0109] A first load capacitor C11, the first end of the first load capacitor C11 is connected to the first end of the crystal oscillator X, and the second end of the first load capacitor C11 is grounded;

[0110] The second load capacitor C12 has its first terminal connected to the second terminal of the crystal oscillator X, and its second terminal grounded.

[0111] The driver 300 is connected to the output of the differential amplifier OP1.

[0112] The crystal oscillator control device of this application has several advantages. First, by using a capacitor voltage divider in conjunction with a low-pass filter, it eliminates the need for complex control logic and programmable adjustments, significantly reducing the complexity of existing crystal oscillator control devices, lowering the difficulty of use, and allowing for better layout matching and guaranteed performance. Second, the capacitor voltage divider not only simplifies the structure but also eliminates the need for additional power consumption, further reducing the overall power consumption of the crystal oscillator control device. By properly configuring the capacitor voltage divider ratio, the power consumption after stabilization can be reduced by about 2 / 3 compared to the power consumption during startup. Third, the capacitor voltage divider design allows for a feedback resistor R0 with a resistance value of KΩ, eliminating the need for a large feedback resistor of tens of MΩ, which helps to reduce the layout area and lower chip costs. Fourth, the use of capacitor voltage divider can automatically reduce the power consumption of the oscillator when stabilizing the output clock. Fifth, the solution of this application is an upgrade or improvement of the existing AGC loop control circuit, and the protection scope is not limited to capacitor voltage divider. Using resistor voltage divider or MOSFET voltage divider to achieve equivalent function also falls within the protection scope of this application. Sixth, the clock signal output by the crystal oscillator in this application is fed back to the self-biased current source through the principle of capacitor voltage divider to reduce power consumption. If the reference current of the self-biased current source is reduced in other ways to reduce the power consumption of the crystal oscillator, it also falls within the protection scope of this application. Seventh, the embodiments of this application are applicable to a relatively wide resonant frequency range (4M to 323M) and drive a large load capacitor. The crystal oscillator can automatically reduce power consumption after oscillation.

[0113] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0114] The above description is the preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principles described in this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A crystal oscillator control device, characterized by comprising: include: The differential amplifier (OP1) has a reference voltage at its first input terminal and a second input terminal connected to the first terminal of the crystal oscillator (X). The output terminal of the differential amplifier (OP1) is connected to the second terminal of the crystal oscillator (X). A self-biasing control module (200) is connected to the output of the crystal oscillator (X); the output of the self-biasing control module (200) is connected to the bias terminal of the differential amplifier (OP1). When the crystal oscillator (X) is in the oscillation state, the voltage amplitude at the output terminal of the differential amplifier (OP1) increases from a first voltage value to a second voltage value, the bias current provided by the self-bias control module (200) to the differential amplifier (OP1) decreases from a first current value to a second current value, and the gain of the differential amplifier (OP1) is greater than a preset gain. When the crystal oscillator (X) is in a resonant state, the voltage amplitude at the output of the differential amplifier (OP1) remains at the second voltage value, the bias current remains at the second current value, and the gain of the differential amplifier (OP1) is reduced to the preset gain value. The self-biasing control module (200) includes: Voltage divider module (210), the first end of which is connected to the output of the differential amplifier (OP1), and the second end of which is connected to the DC power supply (VDD); Self-biased current source (220), the input terminal of the self-biased current source (220) is connected to the voltage divider terminal of the voltage divider module (210), the output terminal of the self-biased current source (220) is connected to the bias terminal, and the power supply terminal of the self-biased current source (220) is connected to the DC power supply (VDD). The voltage divider module (210) is used to divide the voltage output by the differential amplifier (OP1) and provide the first voltage obtained by the voltage division to the self-biased current source (220). The self-biased current source (220) is used to adjust the bias current input to the bias terminal based on the first voltage.

2. The crystal control device according to claim 1, wherein The voltage divider module (210) includes: a first voltage divider element and a second voltage divider element connected in series between the output terminal of the differential amplifier (OP1) and the DC power supply (VDD); The connection point between the first voltage divider element and the second voltage divider element forms the voltage divider end of the voltage divider module (210).

3. The crystal oscillator control device according to claim 2, characterized in that, Both the first voltage divider element and the second voltage divider element are capacitors, resistors, or field-effect transistors.

4. The crystal oscillator control device according to claim 1, characterized in that, The self-biased current source (220) includes: A cascaded mirror current source consisting of a first mirror current source and a second mirror current source; A low-pass filter (221) is connected between the gates of the two MOS transistors of the first mirror current source; The voltage divider module (210) is connected to the input terminal of the low-pass filter (221); the second mirror current source is connected to the bias terminal.

5. The crystal oscillator control device according to claim 4, characterized in that, The low-pass filter (221) includes any of the following: RC filter; LC filter.

6. The crystal oscillator control device according to claim 4, characterized in that, The first mirror current source includes a first metal-oxide-semiconductor field-effect transistor (M1), a second transistor (M2), and a first resistor (R1). The second mirror current source includes a third MOSFET (M3) and a fourth MOSFET (M4); The first resistor (R1) is connected between the first terminal of the first MOSFET (M1) and the DC power supply (VDD). The first terminal of the second MOSFET (M2) is connected to the DC power supply (VDD); The gate of the first MOS transistor (M1) is connected to the output terminal of the low-pass filter (221); The gate of the second MOS transistor (M2), the input terminal of the low-pass filter (221), the second terminal of the second MOS transistor (M2), and the first terminal of the fourth MOS transistor (M4) are all connected to the voltage divider terminal; The second terminal of the first MOS transistor (M1) is connected to the first terminal of the third MOS transistor (M3), the gate of the third MOS transistor (M3), the gate of the fourth MOS transistor (M4), and the bias terminal; The second terminal of the third MOS transistor and the second terminal of the fourth MOS transistor (M4) are grounded; Specifically, when the MOSFET is a PMOS transistor, the first terminal is the source and the second terminal is the drain; when the MOSFET is an NMOS transistor, the first terminal is the drain and the second terminal is the source.

7. The crystal oscillator control device according to claim 1, characterized in that, A fifth MOS transistor (M5) is connected between the self-biased current source (220) and the bias terminal. The gate of the fifth MOS transistor (M5) is connected to the self-biased current source (220), the first terminal of the fifth MOS transistor (M5) is connected to the bias terminal, and the second terminal of the fifth MOS transistor is grounded; wherein, when the fifth MOS transistor (M5) is a PMOS transistor, the first terminal is the source and the second terminal is the drain; when the fifth MOS transistor (M5) is an NMOS transistor, the first terminal is the drain and the second terminal is the source.

8. The crystal oscillator control device according to claim 1, characterized in that, The crystal oscillator control device also includes a feedback resistor (R0) connected in parallel with the crystal oscillator (X). The resistance of the feedback resistor (R0) is NKΩ, where N is greater than or equal to 1 and less than 1000Ω.

9. The crystal oscillator control device according to claim 1, characterized in that, The crystal oscillator control device further includes: A first load capacitor (C11) is connected at its first end to the first end of the crystal oscillator (X), and the second end of the first load capacitor (C11) is grounded. The second load capacitor (C12) has its first terminal connected to the second terminal of the crystal oscillator (X), and its second terminal grounded. The driver (300) is connected to the output of the differential amplifier (OP1).

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