Oscillator capable of linearly adjusting frequency and clock signal frequency adjusting method thereof

Abstract

The invention discloses an oscillator capable of linearly adjusting frequency and a clock signal frequency adjusting method thereof, and solves the problems that at high frequency, output clock frequency and voltage or current of a pin are in nonlinear change, nonlinearity causes that system design cannot be guided through theoretical calculation, and debugging of specific high-frequency frequency can be achieved by multiple trials; according to the oscillator, the overturning delay of the phase inverter is far smaller than the delay of a comparator used in an existing voltage-controlled oscillator, so that the linear relation between the voltage and the frequency of a frequency setting pin is not affected, and compared with a traditional ring oscillator, the linear relation between the voltage or the current of the pin and the frequency is good, so that the frequency setting precision is improved. The frequency of the oscillator can be set in a wide range through external pins, and in addition, due to the fact that voltage or current of the pins of the oscillator is in linear correlation with the frequency, when the high-frequency working frequency is set, design can be guided through theoretical calculation of the linear relation.

Description

Technical Field

[0001] The present invention relates to integrated circuits, and particularly to an oscillator capable of linearly adjusting the frequency and a method for adjusting the clock signal frequency thereof. Background Art

[0002] In analog chips such as switching power supplies, an internal clock signal, i.e., an oscillator, is required. To meet the requirements of different scenarios, a pin is set on the chip to adjust the frequency of the clock signal. However, it is found from the frequency adjustment results that at high frequencies, the output clock frequency has a non-linear relationship with the voltage or current of this pin.

[0003] For existing high-frequency oscillators, in the first solution, a ring oscillator can be used to achieve the design goal of high frequency, but it is impossible to design a linear relationship between the voltage or current of the set pin and the frequency; in the second solution, a common voltage-controlled oscillator can be used, and the charging and discharging current of the capacitor can be designed into a linear relationship by setting the voltage of the pin. However, as the frequency increases, the delay of the comparator in the voltage-controlled oscillator will affect the frequency. It is also possible to design the speed of the comparator to be extremely high, but this will increase the power consumption. To achieve the goals of low power consumption and high frequency, after the frequency reaches a certain value, the relationship between the voltage or current of the set pin and the frequency will become non-linear. Non-linearity will cause the system design to be unable to be guided by theoretical calculations, and multiple attempts are required to obtain a specific high-frequency frequency during debugging. Summary of the Invention

[0004] The object of the present invention is to solve the problem that at high frequencies, the output clock frequency of the existing oscillator has a non-linear change with the voltage or current of the chip pin used to adjust the clock frequency, and when setting the high-frequency operating frequency, it is impossible to be guided by theoretical calculations of linear relationships and multiple attempts are required to obtain the set high-frequency frequency. The present invention provides an oscillator capable of linearly adjusting the frequency and a method for adjusting the clock signal frequency thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides an oscillator capable of linearly adjusting the frequency, which is characterized by comprising:

[0007] A first switching transistor S1, a second switching transistor S2, a storage capacitor C1, a variable linear current source I1, a variable linear current source I3, and a controller;

[0008] The positive electrode of the variable linear current source I1 is connected to the reference voltage Vdd, the negative electrode is connected to the first end of the first switching transistor S1, the second end of the first switching transistor S1 is connected to the positive electrode plate of the energy storage capacitor C1, the negative electrode plate of the energy storage capacitor C1 is connected to the controller, and the variable linear current source I1 is used to charge the energy storage capacitor C1 so that the voltage of the energy storage capacitor C1 reaches the inversion voltage Vth;

[0009] The positive electrode of the variable linear current source I3 is connected to the first end of the second switching transistor S2, the negative electrode is grounded, the second end of the second switching transistor S2 is connected to the second end of the first switching transistor S1 and the positive electrode plate of the energy storage capacitor C1, and the variable linear current source I3 is used to discharge the energy storage capacitor C1, and the discharge voltage difference of the energy storage capacitor C1 is Vm;

[0010] The first switching transistor S1 and the second switching transistor S2 are alternately turned on to control the charging or discharging of the energy storage capacitor C1;

[0011] The input end of the controller is connected to the positive electrode plate of the energy storage capacitor C1, and the output end is respectively connected to the control ends of the first switching transistor S1 and the second switching transistor S2, and is used to control the first switching transistor S1 or the second switching transistor S2 to be turned on according to the voltage at its input end.

[0012] Further, the controller includes an inverter U2, an inverter U3, an inverter U4, a resistor R2, a resistor R3, a capacitor C2, and a capacitor C3;

[0013] The input end of the inverter U2 is connected to the positive electrode plate of the energy storage capacitor C1, the output end is connected to the input end of the inverter U3, the output end of the inverter U3 is respectively connected to the input end of the inverter U4 and the control end of the second switching transistor S2, and the output end of the inverter U4 is connected to the control end of the first switching transistor S1;

[0014] The output end of the inverter U3 is respectively connected to one end of the resistor R2 and the positive electrode plate of the capacitor C2; the other end of the resistor R2 is connected to one end of the resistor R3 and the negative electrode plate of the capacitor C2, the negative electrode plate of the capacitor C2 is also connected to the negative electrode plate of the energy storage capacitor C1 and the positive electrode plate of the capacitor C3, and the negative electrode plate of the capacitor C3 and the other end of the resistor R3 are grounded.

[0015] Further, the controlling the first switching transistor S1 or the second switching transistor S2 to be turned on according to the voltage at its input end specifically is:

[0016] The inversion voltage of the inverter U2 is Vth. When the voltage of the energy storage capacitor C1 is lower than the inversion voltage Vth of the inverter U2, the first switching transistor S1 is turned on and the second switching transistor S2 is turned off;

[0017] When the voltage of the energy storage capacitor C1 is higher than the inversion voltage Vth of the inverter U2, the second switching transistor S2 is turned on and the first switching transistor S1 is turned off.

[0018] Furthermore, the discharge voltage difference Vm and the values of resistors R2 and R3 satisfy the following formula:

[0019] Vm = R3 / (R2 + R3) * Vdd.

[0020] Furthermore, the variable linear current sources I1 and I3 have the same structure, and both include a fixed current source I2, a variable resistor R1, and a transconductance amplifier U1;

[0021] The positive pole of the fixed current source I2 is connected to the reference voltage Vdd, the negative pole of the fixed current source I2 is respectively connected to one end of the variable resistor R1 and the non-inverting input terminal of the transconductance amplifier U1, the inverting input terminal of the transconductance amplifier U1 is connected to the positive pole of the reference voltage Vbg, and the negative pole of the reference voltage Vbg and the other end of the variable resistor R1 are both grounded. Adjust the resistance value of the variable resistor R1 to linearly adjust the current value of the variable current source;

[0022] The output terminal of the transconductance amplifier U1 in the variable linear current source I1 is connected to the reference voltage Vdd, and the negative pole is grounded and connected to the first end of the first switching transistor S1;

[0023] The output terminal of the transconductance amplifier U1 in the variable linear current source I3 is connected to the first end of the second switching transistor S2, and the negative pole is grounded.

[0024] Furthermore, the capacitance value of the capacitor C3 is 1 / 5 to 1 / 10 times the capacitance value of the energy storage capacitor C1; the capacitance value of the capacitor C2 is C3 * R3 / R2.

[0025] Meanwhile, the present invention also provides a clock signal frequency adjustment method for an oscillator capable of linearly adjusting the frequency within a wide range, which is characterized in that it includes the following steps:

[0026] Step 1: Control the first switching transistor S1 to conduct through the controller, and the variable linear current source I1 charges the energy storage capacitor C1, and the voltage of the energy storage capacitor C1 increases;

[0027] Step 2: When the voltage of the energy storage capacitor C1 reaches the flip voltage Vth, control the second switching transistor S2 to conduct through the controller, and discharge the energy storage capacitor C1 through the variable linear current source I3;

[0028] Step 3: When the voltage of the energy storage capacitor C1 drops by Vm, control the first switching transistor S1 to conduct;

[0029] Step 4: Repeat steps 1 - 3, and alternately execute the charge - discharge process of the energy storage capacitor C1;

[0030] During the charging and discharging process of the energy storage capacitor C1, a stable clock signal with a target frequency is obtained by linearly adjusting the output current of the variable linear current source I1 or the variable linear current source I3, and the frequency adjustment of the clock signal is completed.

[0031] Further, step 1 is specifically as follows: In the initial state, the variable linear current source I3 and the variable linear current source I1 are started. The potential of the positive plate of the energy storage capacitor C1 is 0, which is lower than the flip voltage of the inverter U2. The output of the inverter U3 is low, controlling the first switching transistor S1 to conduct, and the variable linear current source I1 charges the energy storage capacitor C1. The voltage of the negative plate of the energy storage capacitor C1 is 0.

[0032] Step 2 is specifically as follows: When the potential of the positive plate of the energy storage capacitor C1 reaches the flip voltage of the inverter U2, the output of the inverter U3 is high, controlling the second switching transistor S2 to conduct, and discharging the energy storage capacitor C1 through the variable linear current source I3; at this time, the potential of the negative plate of the energy storage capacitor C1 is raised by Vm.

[0033] Step 3 is specifically as follows: When the potential of the positive plate of the energy storage capacitor C1 discharges to the flip voltage Vth of the inverter U2, the output of the inverter U3 is low, controlling the first switching transistor S1 to conduct, the voltage of the negative plate of the energy storage capacitor C1 is 0, and the potential of the negative plate of the energy storage capacitor C1 is reduced by Vm.

[0034] Further, in step 2, the linear adjustment of the output current of the variable linear current source I1 or the variable linear current source I3 is specifically as follows:

[0035] Linearly adjust the resistance value of the variable resistor R1 in the variable linear current source I1 or the variable linear current source I3.

[0036] Advantages of the present invention:

[0037] 1. The oscillator with linearly adjustable frequency of the present invention adopts variable linear current sources I1 and I3 with linearly adjustable output currents, combined with the alternating conduction of the first switching transistor S1 and the second switching transistor S2, enabling the energy storage element to alternately charge-discharge-charge... By linearly adjusting the output currents of the variable linear current source I1 and the variable linear current source I3, a linearly adjustable clock frequency signal can be obtained; compared with the traditional ring oscillator, since the linear relationship between the voltage or current of the pins of the oscillator of the present invention and the frequency is good, a relatively wide range of oscillator frequencies can be set through the pins of the external chip, such as 50 kHz to 10 MHz, and the maximum frequency differs from the minimum frequency by 200 times.

[0038] 2. In an oscillator with linearly adjustable frequency according to the present invention, when operating at high frequencies, since the flip delay of the inverter U2 is much smaller than the delay of the comparator used in the existing voltage-controlled oscillator, it will not affect the linear relationship between the voltage or current of the frequency setting chip pin and the frequency.

[0039] 3. An oscillator with linearly adjustable frequency according to the present invention can omit the design of 1 to 2 comparators compared with the traditional voltage-controlled oscillator, reducing the power consumption and cost of the oscillator. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is the circuit diagram of the current source in the embodiment of the oscillator with linearly adjustable frequency according to the present invention;

[0041] Figure 2 It is the circuit diagram of the embodiment of the oscillator with linearly adjustable frequency according to the present invention;

[0042] Figure 3 It is the simulation diagram of the relationship between the voltage of the existing high-frequency oscillator setting pin A and the frequency in the embodiment of the present invention;

[0043] Among them, the abscissa represents the pin voltage, and the ordinate represents the frequency;

[0044] Figure 4 It is the simulation diagram of the relationship between the voltage of the setting pin A and the frequency in the embodiment of the oscillator with linearly adjustable frequency according to the present invention;

[0045] Among them, the abscissa represents the voltage of the setting pin A, and the ordinate represents the frequency. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0047] In order to improve the linear relationship between the voltage or current of the frequency setting pin and the frequency, this embodiment provides an oscillator with linearly adjustable frequency.

[0048] In this embodiment, variable linear current sources I1 and I3 with linearly adjustable output currents are used, as Figure 1As shown, it includes a fixed current source I2. The positive electrode of the fixed current source I2 is connected to the reference voltage Vdd, and the negative electrode is respectively connected to the non-inverting input terminal of the transconductance amplifier U1 and one end of the variable resistor R1. The other end of the variable resistor R1 is grounded. The positive electrode of the reference voltage Vbg is connected to the inverting input terminal of the transconductance amplifier U1, and the negative electrode is grounded. The positive electrode of the variable linear current source I1 is connected to the output terminal of the transconductance amplifier U1, and the negative electrode is grounded. The output terminal of the transconductance amplifier U1 serves as the positive electrode of the current source, and the corresponding grounded wire serves as the negative electrode of the current source.

[0049] In this embodiment, the working principle of the current source whose output current can be linearly adjusted is as follows: As Figure 1 shown, by connecting one end of a variable resistor R1 to pin A of the transconductance amplifier U1, the current of the variable resistor R1 is a fixed current. When the resistance value of the variable resistor R1 changes linearly, the voltage VA generated at pin A changes linearly with the variable resistor R1. The voltage VA at pin A is converted into a current I through the transconductance amplifier U1. Then, the current I changes linearly with the variable resistor R1. Therefore, linearly adjusting the variable resistor R1 can obtain a linearly varying current I, and the current I serves as Figure 2 the output currents of the variable linear current source I1 and the variable linear current source I3 in

[0050] As Figure 2 shown, the oscillator in this embodiment that can linearly adjust the frequency over a wide range includes a variable linear current source I1 with a linear change. The positive electrode of the variable linear current source I1 is connected to the reference voltage Vdd, and the negative electrode is connected to the first end of the first switching transistor S1. The second end of the first switching transistor S1 is simultaneously connected to the positive electrode plate of the energy storage capacitor C1 and the second end of the second switching transistor S2. The input terminal of the inverter U2 is connected to the positive electrode plate of the energy storage capacitor C1; the output terminal of the inverter U2 is connected to the input terminal of the inverter U3, the output terminal of the inverter U3 is connected to the input terminal of the inverter U4 and the control terminal of the second switching transistor S2, and the output terminal of the inverter U4 is connected to the control terminal of the first switching transistor S1; the first end of the second switching transistor S2 is connected to the positive electrode of the variable linear current source I3, and the negative electrode of the variable linear current source I3 is grounded; the negative electrode plate of the energy storage capacitor C1 is respectively connected to the negative electrode plate of the capacitor C2 and the positive electrode plate of the capacitor C3. The negative electrode plate of the capacitor C3 is grounded, and the positive electrode plate of the capacitor C2 is connected to the input terminal of the inverter U4; it also includes a series-connected resistor R2 and resistor R3. One end of the resistor R2 in series with the resistor R3 is connected to the negative electrode plate of the capacitor C2, and the other end is connected to the input terminal of the inverter U4; the end of the resistor R3 far from the resistor R2 is grounded.

[0051] In this embodiment, the structures of the variable linear current source I1 and the variable linear current source I3 are as Figure 1As shown, the output terminal of the transconductance amplifier U1 of the variable linear current source I1 serves as the positive pole of the variable linear current source I1, and the corresponding grounded wire serves as the negative pole of the variable linear current source I1; the output terminal of the transconductance amplifier U1 of the variable linear current source I3 serves as the positive pole of the variable linear current source I3, and the corresponding grounded wire serves as the negative pole of the variable linear current source I3.

[0052] The working principle of the oscillator capable of linearly adjusting the frequency within a wide range in this embodiment is as follows:

[0053] In the initial state, the potential of the positive plate of the energy storage capacitor C1 is 0, which is lower than the flip voltage of the inverter U2. The output of the inverter U3 is low, and the first switching transistor S1 is turned on. The variable linear current source I1 charges the energy storage capacitor C1. The charging circuit is as follows: starting from Vdd, it passes through the variable linear circuit source I1, the first switching transistor S1, the energy storage capacitor C1, and the resistor R3 to ground in sequence. At this time, the voltage of the lower plate of the energy storage capacitor C1 is 0; when the potential of the energy storage capacitor C1 is charged to be higher than the flip point of the inverter U2, the output of the inverter U3 is high, and the voltage of the lower plate of the energy storage capacitor C1 is Vm = R3 / (R2 + R3)*Vdd. The potential of the lower plate of the energy storage capacitor C1 is raised by Vm, the output of the inverter U3 is high, the first switching transistor S1 is turned off, and the second switching transistor S2 is turned on. The variable linear current source I3 discharges the energy storage capacitor C1. The discharging circuit is as follows: starting from the energy storage capacitor C1, it passes through the variable linear current source I3 to ground; when the potential of the energy storage capacitor C1 is discharged to be lower than the flip voltage Vth of the inverter U2, the output of the inverter U3 is low. At this time, the voltage of the lower plate of the energy storage capacitor C1 is 0, the potential of the negative plate of the energy storage capacitor C1 is reduced by Vm, the output of the inverter U3 is low again, the first switching transistor S1 is turned on, and the variable linear current source I1 charges the energy storage capacitor C1; this cycle repeats, and the oscillator operates normally.

[0054] In this embodiment, the flip voltage Vth of the inverter U2 and the values of the resistor R2 and the resistor R3 satisfy the following formula:

[0055] Vm = R3 / (R2 + R3)*Vdd.

[0056] When the charging and discharging currents are equal, the charging and discharging times can be guaranteed to be equal, which is convenient for design.

[0057] In this embodiment, the capacitance C3 is taken as 1 / 5 to 1 / 10 times the capacitance value of the energy storage capacitor C1. The capacitance value of the capacitor C2 and the capacitance value of the capacitor C3 satisfy the following relationship: C2 = C3*R3 / R2. At this time, the filtering effect is the best.

[0058] This embodiment also provides a method for adjusting the frequency of a clock signal, including the following steps:

[0059] Step 1: Control the first switch tube S1 to conduct through the controller, and the variable linear current source I1 charges the energy storage capacitor C1, and the voltage of the energy storage capacitor C1 increases. Specifically: In the initial state, start the variable linear current source I3 and the variable linear current source I1. The potential of the positive plate of the energy storage capacitor C1 is 0, which is lower than the flip voltage of the inverter U2. The output of the inverter U3 is low. Control the first switch tube S1 to conduct, and the variable linear current source I1 charges the energy storage capacitor C1. The voltage of the negative plate of the energy storage capacitor C1 is 0.

[0060] Step 2: When the voltage of the energy storage capacitor C1 reaches the flip voltage Vth, control the second switch tube S2 to conduct through the controller, and discharge the energy storage capacitor C1 through the variable linear current source I3. Specifically: When the potential of the positive plate of the energy storage capacitor C1 reaches the flip voltage of the inverter U2, the output of the inverter U3 is high. Control the second switch tube S2 to conduct, and discharge the energy storage capacitor C1 through the variable linear current source I3. At this time, the potential of the negative plate of the energy storage capacitor C1 is raised by Vm.

[0061] Step 3: When the voltage of the energy storage capacitor C1 drops by Vm, control the first switch tube S1 to conduct. Specifically: When the potential of the positive plate of the energy storage capacitor C1 discharges to the flip voltage Vth of the inverter U2, the output of the inverter U3 is low. Control the first switch tube S1 to conduct. The voltage of the negative plate of the energy storage capacitor C1 is 0, and the potential of the negative plate of the energy storage capacitor C1 is reduced by Vm.

[0062] Step 4: Repeat Step 1 - Step 3, and alternately execute the charge - discharge process of the energy storage capacitor C1.

[0063] During the charge - discharge process of the energy storage capacitor C1, by linearly adjusting the output current of the variable linear current source I1 or the variable linear current source I3, a clock signal with a stable target frequency is obtained, and the clock signal frequency adjustment is completed.

[0064] Simulate the relationship between the voltage and frequency of pin A of the existing high - frequency oscillator. The simulation results are as Figure 3 shown. The horizontal axis in the figure represents the voltage set at pin A, and the vertical axis represents the frequency of the clock signal. It can be seen from the figure that there is a deviation between the simulation data of the existing technology and the technical theory data. When the frequency is 6 MHz, the error between the simulation frequency and the theoretical frequency is 250 kHz. As the frequency increases, the error between the simulation frequency and the theoretical frequency becomes larger, and the pin voltage and the oscillator frequency become more and more non - linear.

[0065] Simulate the relationship between the voltage and frequency of pin A of the high - frequency oscillator in this embodiment. The simulation results are as Figure 4As shown in the figure, the horizontal axis represents the voltage of the set pin, and the vertical axis represents the frequency of the clock signal. It can be seen from the figure that as the pin voltage increases, the frequency of the clock signal increases linearly. Moreover, when the pin voltage increases, the curves of the simulation data and the theoretical simulation data of the present invention are parallel. When fs = 9 MHz, the error between the simulation frequency and the theoretical frequency is only 150 kHz. The linear relationship between the pin voltage and the oscillator frequency is relatively good. When setting the high-frequency operating frequency of the present invention, the design can be guided by the theoretical calculation of the linear relationship.

[0066] As described above, it is only the specific implementation manner of the present invention and the effect comparison between the relevant specific implementation manner and the related comparative example. However, the protection scope of the present invention is not limited thereto. Any change or replacement within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claimed rights.

Claims

1. An oscillator with linearly adjustable frequency, characterized in that: include: A first switch tube S1, a second switch tube S2, an energy storage capacitor C1, a variable linear current source I1, a variable linear current source I3 and a controller; The positive electrode of the variable linear current source I1 is connected to the reference voltage Vdd, the negative electrode is connected to the first end of the first switch tube S1, the second end of the first switch tube S1 is connected to the positive plate of the energy storage capacitor C1, the negative plate of the energy storage capacitor C1 is connected to the controller, and the variable linear current source I1 is used to charge the energy storage capacitor C1 so that the voltage of the energy storage capacitor C1 reaches the flip voltage Vth; The positive electrode of the variable linear current source I3 is connected to the first end of the second switch tube S2, and the negative electrode is grounded. The second end of the second switch tube S2 is connected to the second end of the first switch tube S1 and the positive plate of the energy storage capacitor C1. The variable linear current source I3 is used to discharge the energy storage capacitor C1. The discharge voltage difference of the energy storage capacitor C1 is Vm. The first switch tube S1 and the second switch tube S2 are alternately turned on to control the charging or discharging of the energy storage capacitor C1; The controller has an input end connected to the positive plate of the energy storage capacitor C1, and an output end connected to the control end of the first switch tube S1 and the control end of the second switch tube S2, for controlling the first switch tube S1 or the second switch tube S2 to conduct according to the input end voltage.

2. The oscillator with linearly adjustable frequency according to claim 1, characterized in that: The controller includes an inverter U2, an inverter U3, an inverter U4, a resistor R2, a resistor R3, a capacitor C2 and a capacitor C3; The input end of the inverter U2 is connected to the positive plate of the energy storage capacitor C1, and the output end is connected to the input end of the inverter U3. The output end of the inverter U3 is respectively connected to the input end of the inverter U4 and the control end of the second switch tube S2. The output end of the inverter U4 is connected to the control end of the first switch tube S1. The output end of the inverter U3 is respectively connected to one end of the resistor R2 and the positive plate of the capacitor C2; the other end of the resistor R2 is connected to one end of the resistor R3 and the negative plate of the capacitor C2, the negative plate of the capacitor C2 is also connected to the negative plate of the energy storage capacitor C1 and the positive plate of the capacitor C3, the negative plate of the capacitor C3 and the other end of the resistor R3 are grounded.

3. The oscillator with linearly adjustable frequency according to claim 2, characterized in that: The method of controlling the first switch tube S1 or the second switch tube S2 to be turned on according to the voltage at the input terminal thereof is specifically as follows: The flip voltage of the inverter U2 is Vth. When the voltage of the energy storage capacitor C1 is lower than the flip voltage Vth of the inverter U2, the first switch tube S1 is turned on and the second switch tube S2 is turned off. When the voltage of the energy storage capacitor C1 is higher than the flip voltage Vth of the inverter U2 , the second switch tube S2 is turned on, and the first switch tube S1 is turned off.

4. The oscillator with linearly adjustable frequency according to claim 2, characterized in that: The discharge voltage difference Vm and the values ​​of the resistor R2 and the resistor R3 satisfy the following formula: Vm=R3 / (R2+R3)*Vdd.

5. The oscillator with linearly adjustable frequency according to claim 1, characterized in that: The variable linear current source I1 has the same structure as the variable linear current source I3, both of which include a fixed current source I2, a variable resistor R1 and a transconductance amplifier U1; The positive electrode of the fixed current source I2 is connected to the reference voltage Vdd, the negative electrode of the fixed current source I2 is respectively connected to one end of the variable resistor R1 and the non-inverting input end of the transconductance amplifier U1, the inverting input end of the transconductance amplifier U1 is connected to the positive electrode of the reference voltage Vbg, the negative electrode of the reference voltage Vbg and the other end of the variable resistor R1 are both grounded, and the current value of the variable current source is linearly adjusted by adjusting the resistance value of the variable resistor R1; The output end of the transconductance amplifier U1 serves as the positive electrode of the variable linear current source I1 and the variable linear current source I3; The reference voltage Vbg is placed in the negative electrode as the negative electrode of the variable linear current source I1 and the variable linear current source I3.

6. The oscillator with linearly adjustable frequency according to claim 1, characterized in that: The capacitance value of the capacitor C3 is 1 / 5 to 1 / 10 times the capacitance value of the energy storage capacitor C1; the capacitance value of the capacitor C2 is C3*R3 / R2.

7. A method for adjusting the frequency of a clock signal of an oscillator with linearly adjustable frequency according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: The controller controls the first switch tube S1 to be turned on, and the variable linear current source I1 charges the energy storage capacitor C1, and the voltage of the energy storage capacitor C1 increases; Step 2: When the voltage of the energy storage capacitor C1 reaches the flip voltage Vth, the controller controls the second switch tube S2 to be turned on, and the energy storage capacitor C1 is discharged through the variable linear current source I3; Step 3: When the voltage of the energy storage capacitor C1 decreases to Vm, the first switch tube S1 is controlled to be turned on; Step 4, repeating steps 1 to 3, alternately performing the charging and discharging process of the energy storage capacitor C1; During the charging and discharging process of the energy storage capacitor C1, a stable clock signal of a target frequency is obtained by linearly adjusting the output current of the variable linear current source I1 or the variable linear current source I3, thereby completing the frequency adjustment of the clock signal.

8. The method for adjusting the frequency of a clock signal according to claim 7, characterized in that: Step 1 is specifically as follows: in the initial state, the variable linear current source I3 and the variable linear current source I1 are started, the positive plate potential of the energy storage capacitor C1 is 0, which is lower than the flip voltage of the inverter U2, the output of the inverter U3 is low, the first switch tube S1 is controlled to be turned on, the variable linear current source I1 charges the energy storage capacitor C1, and the negative plate voltage of the energy storage capacitor C1 is 0; Step 2 is specifically as follows: when the potential of the positive plate of the energy storage capacitor C1 reaches the flip voltage of the inverter U2, the output of the inverter U3 is high, the second switch tube S2 is controlled to be turned on, and the energy storage capacitor C1 is discharged through the variable linear current source I3; at this time, the potential of the negative plate of the energy storage capacitor C1 is raised by Vm; Step 3 is specifically as follows: when the positive plate potential of the energy storage capacitor C1 is discharged to the flip voltage Vth of the inverter U2, the inverter U3 output is low, the first switch tube S1 is controlled to be turned on, the negative plate voltage of the energy storage capacitor C1 is 0, and the potential of the negative plate of the energy storage capacitor C1 is reduced by Vm.

9. The method for adjusting the frequency of a clock signal according to claim 8, characterized in that: In step 2, the linear adjustment of the output current of the variable linear current source I1 or the variable linear current source I3 is specifically: linear adjustment of the resistance value of the variable resistor R1 in the variable linear current source I1 or the variable linear current source I3.

Images