A single power supply voltage frequency adjustable charge pump voltage boosting circuit

Abstract

The application discloses a single-power-supply charge pump voltage boosting circuit with adjustable oscillation frequency, and belongs to the technical field of basic electronic circuits. The charge pump voltage boosting circuit comprises an oscillator and a diode circuit. The oscillator generates an alternating oscillation voltage with adjustable frequency by changing RC parameters, stores charges in an energy storage capacitor, and increases an output voltage; and the diode circuit is used for unidirectional conduction and rectification, realizes the flow direction of the charges stored in the energy storage capacitor to an output capacitor, and simultaneously realizes rectification output of a direct current voltage. The charge pump voltage boosting circuit in the application is powered by a single power supply, the oscillator has the function of adjustable oscillation frequency, and can adapt to loads with different ripple requirements.

Description

Technical Field

[0001] This invention discloses a charge pump boost circuit with adjustable single-power-supply oscillation frequency, belonging to the field of basic electronic circuit technology. Background Technology

[0002] A charge pump circuit is a circuit that uses capacitors to achieve voltage conversion under switch control. Compared with traditional inductive boost DC / DC circuits, charge pump boost circuits do not rely on magnetic components, but instead rely on capacitor energy storage and charge transfer to achieve voltage boost, offering advantages such as small size and simple structure. They are widely used in low-power scenarios and space-constrained systems such as consumer electronics, display technology, and power device drivers.

[0003] The oscillator is a crucial component of a charge pump circuit. The amplitude and frequency of the oscillator's output waveform determine the output voltage and ripple of the charge pump. Increasing the oscillator frequency can effectively reduce the energy storage capacitor capacity, thereby reducing the circuit size.

[0004] However, existing charge pump boost circuits require dual power supplies or an external reference power supply to operate, resulting in high system costs. The difficulty in adjusting the oscillator frequency in charge pump boost circuits limits the output voltage regulation range and operating efficiency. Furthermore, the limited switching timing in some charge pump circuits leads to high output voltage ripple, affecting the stability of subsequent circuits. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the aforementioned background technology by providing a charge pump boost circuit with adjustable oscillation frequency under single-power supply conditions. This circuit generates an adjustable frequency AC oscillation voltage in single-power supply scenarios, alternately charging and boosting the voltage of the energy storage capacitor using this adjustable AC oscillation voltage. This solves the technical problems of complex charge pump circuit structure, single oscillator frequency, and high output ripple voltage, making the charge pump more adaptable to various application scenarios. The invention achieves the objective of adjusting the oscillation frequency and reducing output ripple under single-power supply conditions through a simple charge pump boost circuit.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0007] A charge pump boost circuit with adjustable single-supply oscillation frequency includes: a diode circuit, an oscillator, an energy storage capacitor, and an output capacitor; the diode circuit is connected between a DC voltage input port and a DC voltage output port, providing a unidirectional conduction path for the charge stored in the energy storage capacitor to flow to the output capacitor, and rectifying the voltage output after charging the energy storage capacitor; the oscillator is a symmetrical circuit structure connected between the DC voltage input port and a reference ground, used to generate two AC oscillation voltages with adjustable frequencies, either of which charges the energy storage capacitor; the energy storage capacitor is connected between the AC oscillation voltage output port of the oscillator and the diode circuit; the output capacitor is connected between the output terminal of the diode circuit and the reference ground.

[0008] As a further optimization of a charge pump boost circuit with adjustable single-supply oscillation frequency, the diode circuit includes: a first diode and a second diode; the anode of the first diode is connected to the DC voltage input port; the anode of the second diode is connected to the cathode of the first diode and one pole of the energy storage capacitor.

[0009] As a further optimization of a charge pump boost circuit with adjustable single-supply oscillation frequency, the oscillator includes: a first resistor, a third resistor, a first NMOS transistor, a second resistor, a first capacitor, a second capacitor, a fourth resistor, and a second NMOS transistor; one end of the first resistor is connected to the DC voltage input port; one end of the third resistor is connected to the DC voltage input port; the drain of the first NMOS transistor is connected to the other end of the first resistor, and its source is connected to reference ground; one end of the second resistor is connected to the drain of the first NMOS transistor, and the other end is connected to the gate of the first NMOS transistor; one terminal of the first capacitor is connected to the drain of the first NMOS transistor; one terminal of the second capacitor is connected to the gate of the first NMOS transistor; one end of the fourth resistor is connected to the other terminal of the second capacitor and the other end of the third resistor; the drain of the second NMOS transistor is connected to the other end of the third resistor and the other terminal of the energy storage capacitor, its gate is connected to the other end of the fourth resistor and the other terminal of the first capacitor, and its source is connected to reference ground.

[0010] As a further optimization of a charge pump boost circuit with adjustable oscillation frequency from a single power supply, the oscillator generates two AC oscillation voltages with adjustable frequencies as follows: the oscillation frequency is determined by selecting the parameters of the first resistor, second resistor, third resistor, fourth resistor, first capacitor, and second capacitor. The frequency of the AC oscillation voltage output from the drain of any one of the NMOS transistors in the oscillator is adjustable, and the energy storage capacitor is charged from the drain of one of the NMOS transistors. The two AC oscillation voltages at the determined oscillation frequency are generated in the following manner:

[0011] From the initial state to time t0, the first NMOS transistor is turned on and the second NMOS transistor is turned off. The voltage at the connection point between the anode of the second diode and the cathode of the first diode and one terminal of the energy storage capacitor is the sum of the input DC voltage and the drain voltage of the second NMOS transistor, minus the forward voltage drop of the first diode.

[0012] From time t0 to time t1, the first NMOS transistor is turned off and the second NMOS transistor is turned on. The voltage at the connection point between the anode of the second diode and the cathode of the first diode and one terminal of the energy storage capacitor is the difference between the input DC voltage and the forward conduction voltage drop of the first diode.

[0013] As a further optimization of a charge pump boost circuit with adjustable single-supply oscillation frequency, the load is connected between the output of the diode circuit and the reference ground.

[0014] As a further optimization of a charge pump boost circuit with adjustable single-supply oscillation frequency, adapting to loads with different ripple requirements means that, with the same output capacitor capacity, the output voltage ripple can be adjusted by the oscillator frequency.

[0015] The topology of the charge pump boost circuit is suitable for applications such as consumer electronics, display technology, and power device driving.

[0016] The present invention, employing the above-mentioned technical solution, has the following beneficial effects: The present invention provides a charge pump boost circuit with adjustable single-supply oscillation frequency. This circuit realizes the boosting of the input DC voltage source VIN to the output DC voltage source VOUT under single-supply power supply, and has the following advantages:

[0017] 1. The single power supply structure can be directly shared with the system's main power supply, reducing system complexity and power consumption;

[0018] 2. The oscillator frequency is adjustable, which can realize high-frequency alternating AC output. The alternating output frequency adjustable AC oscillation voltage charges the energy storage capacitor on the one hand and raises the voltage of the energy storage capacitor on the other hand. Therefore, the oscillation frequency can be adjusted without dual power supply or external reference power supply, reducing the circuit size while effectively reducing the output voltage ripple, expanding the output voltage adjustment range of the charge pump boost circuit and improving working efficiency.

[0019] 3. The ripple voltage of both the output DC current and the output DC voltage of the present invention can be adjusted, thus allowing for design according to the needs of different application scenarios. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the charge pump boost circuit of the present invention.

[0021] Figure 2 This is a schematic diagram of a charge pump boost circuit provided in one embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the operating voltage waveform of the charge pump boost circuit provided in one embodiment of the present invention.

[0023] Figure 4 This is an example of the input voltage and output voltage waveforms provided in one embodiment of the present invention.

[0024] Figure 5 This is an output current waveform diagram provided in one embodiment of the present invention.

[0025] Figure 6 This is a schematic diagram illustrating an adjustable output voltage obtained under the same input voltage in one embodiment of the present invention.

[0026] Figure 7 This is a schematic diagram of different ripple output voltages obtained by changing the RC parameters in one embodiment of the present invention.

[0027] The following are the labels in the diagram: D1, first diode; D2, second diode; Q1, first NMOS transistor; Q2, second NMOS transistor; C1, first capacitor; C2, second capacitor; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; Cpump, energy storage capacitor; Cout, output capacitor; Rload, load. Detailed Implementation

[0028] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0029] The charge pump boost circuit of the present invention includes an oscillator and a diode circuit, according to Figure 1 The circuit diagram shown illustrates the process of selecting appropriate component models. The oscillator generates an adjustable-frequency AC oscillation voltage by changing the RC parameters, storing charge in the energy storage capacitor Cpump and increasing the output voltage. The diode circuit is used for unidirectional conduction and rectification. The unidirectional conduction function of the diode circuit allows the charge stored in the energy storage capacitor Cpump to flow to the output capacitor Cout, while the rectification function of the diode circuit achieves the DC voltage output. The charge pump boost circuit in this invention uses a single power supply, and the oscillator has an adjustable oscillation frequency to adapt to loads with different ripple requirements.

[0030] In one embodiment of the present invention, a method is provided. Figure 2The circuit shown is a charge pump boost circuit. The oscillator includes: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2, a first NMOS transistor Q1, and a second NMOS transistor Q2. The diode circuit consists of a first diode D1 and a second diode D2. The oscillator and the diode circuit share a DC voltage source VIN. The input DC voltage source VIN is connected to the anode of the first diode D1, the cathode of the first diode D1 is connected to the anode of the second diode D2, and the cathode of the second diode D2 outputs the rectified DC voltage VOUT. The input DC voltage source VIN is connected to the common terminal of the first resistor R1 and the third resistor R3. The other end of the third resistor R3, one end of the fourth resistor R4, one terminal of the second capacitor C2, the drain of the second NMOS transistor Q2, and one terminal of the energy storage capacitor Cpump are connected. The gate of the second NMOS transistor Q2 is connected to the other end of the fourth resistor R4 and one terminal of the first capacitor C1. The other terminal of the first capacitor C1 is connected to the first NMOS transistor Q2. The other end of resistor R1, one end of resistor R2, and the drain of the first NMOS transistor Q1 are connected. The gate of the first NMOS transistor Q1 is connected to the other end of resistor R2 and the other terminal of capacitor C2. The other terminal of energy storage capacitor Cpump is connected to the cathode of diode D1. The cathode of diode D1 is connected to the anode of diode D2. The cathode of diode D2 is connected to the common terminal of output capacitor Cout and load Rload. The other terminal of output capacitor Cout, the other end of load Rload, the source of first NMOS transistor Q1, and the source of second NMOS transistor Q2 are all connected to reference ground. Node 1 is the input voltage VIN, node 2 is the voltage Vpump before rectification by the charge pump, node 3 is the rectified output voltage VOUT, node 4 is the drain voltage Vd1 of first NMOS transistor Q1, node 5 is the drain voltage Vd2 of second NMOS transistor Q2, node 6 is the gate voltage Vg1 of first NMOS transistor Q1, node 7 is the gate voltage Vg2 of second NMOS transistor Q2, and node 8 is the reference voltage GND for the entire circuit.

[0031] Combination Figure 2 The charge pump boost circuit shown in the embodiment of the present invention and Figure 3 The schematic diagram of the working voltage waveform of the charge pump boost circuit shown in the embodiment of the present invention analyzes the working principle of the charge pump boost circuit.

[0032] From the initial state to time t0, the gate voltage Vg1 of the first NMOS transistor Q1 in the oscillator circuit reaches the threshold voltage Vth, and the first NMOS transistor Q1 turns on. The voltage Vd1 at node 4 becomes 0V. The gate voltage Vg2 of the second NMOS transistor Q2 at node 7 is less than the threshold voltage Vth. The negative value of the voltage Vg2 at node 7 is mainly due to the sudden change of the voltage Vd1 at node 4 connected to the first capacitor C1 from positive to 0V. According to the principle of charge conservation, the voltage Vg2 at node 7 will suddenly become negative, and the second NMOS transistor Q2 is in the off state. Therefore, the voltage Vd2 at node 5 is the voltage division of the input voltage VIN in the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the first capacitor C1, the second capacitor C2, and the load Rload. The slow rise of the drain voltage Vd2 of the second NMOS transistor Q2 is caused by the load size and the RC time constant. When a smaller RC time constant and a lighter load are selected, the waveform of the voltage Vd2 at node 5 will rise more steeply. The voltage Vpump at node 2 is the sum of the input voltage VIN and the voltage Vd2 at node 5, but the forward voltage drop VF of the first diode D1 needs to be taken into account.

[0033] From time t0 to time t1, the voltage Vg1 at node 6 is lower than the threshold voltage Vth. The main reason for the negative value of the voltage Vg1 at node 6 is that the voltage Vd2 at node 5 to the right of capacitor C2 suddenly changes from positive to 0V. According to the principle of charge conservation, the voltage Vg1 at node 6 will suddenly become negative at time t0. The first NMOS transistor Q1 is turned off, and the voltage Vd1 at node 4 becomes high. The amplitude of the voltage Vd1 at node 4 is higher than the amplitude of the voltage Vd2 at time t0 because Vd1 has no load. The gate voltage Vg2 of the NMOS transistor Q2 at node 7 is greater than the threshold voltage Vth, and the second NMOS transistor Q2 is in the turned-on state. Therefore, the voltage Vd2 at node 5 is 0V, and the voltage Vpump at node 2 is VIN-VF.

[0034] The circuit operates in the same state from time t1 to time t2 as it does from the initial time to time t0. It should be noted that during the period from time t1 to time t2, the voltage Vg1 at node 6 will gradually decrease to the threshold voltage Vth of the NMOS transistor. The threshold voltages of the first NMOS transistor Q1 and the second NMOS transistor Q2 can be the same or different. It is recommended to use the same NMOS transistor.

[0035] Figure 4 The input and output voltage waveforms of the charge pump boost circuit in this embodiment of the invention show that when the input voltage VIN is 10V, the output voltage VOUT gradually increases and tends to stabilize. Here, in order to highlight the influence of the output voltage ripple on the output voltage, the oscillator frequency is set to be low, so the output voltage ripple is very obvious.

[0036] Figure 5 The output current waveform of the charge pump boost circuit in this embodiment of the invention shows that when the input voltage VIN is 10V, the trend of the output current IOUT is consistent with the output voltage. The load resistor is selected as 9KΩ.

[0037] Figure 6 This diagram illustrates the adjustable output voltage waveform obtained by the charge pump boost circuit of this invention under the same input voltage. By keeping the second resistor R2 and the fourth resistor R4 constant, adjusting the values ​​of the first resistor R1 and the third resistor R3 can achieve different output voltages under the same input voltage. It should be noted that this is only one way to adjust the output voltage; different output voltages VOUT1, VOUT2, VOUT3, and VOUT4 can be obtained with an input voltage of 10V. The output DC voltage of this invention is adjustable, and therefore can be designed according to the needs of different application scenarios.

[0038] Figure 7 This is a schematic diagram of different ripple output voltages obtained by changing the RC parameters according to the present invention. Changing the RC parameters can change the oscillator frequency, thereby achieving different ripple output voltages. In order to highlight the comparison of ripple magnitude, four different output voltages are used to correspond to four different oscillation frequencies. As the oscillator frequency increases, the output ripple voltage becomes smaller and smaller.

[0039] The above description is only a part of the embodiments of the present invention, and not all of them. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A charge pump boost circuit with adjustable single-supply oscillation frequency, characterized in that, include: A diode circuit is connected between the DC voltage input port and the DC voltage output port to provide a unidirectional conduction path for the charge stored in the energy storage capacitor to flow to the output capacitor, and to rectify and output the voltage after the energy storage capacitor is charged. An oscillator is a symmetrical circuit structure connected between a DC voltage input port and a reference ground, used to generate two AC oscillating voltages with adjustable frequencies, either of which charges an energy storage capacitor. The energy storage capacitor is connected between the AC oscillation voltage output port of the oscillator and the diode circuit; and, The output capacitor is connected between the output terminal of the diode circuit and the reference ground.

2. The charge pump boost circuit with adjustable single-power-supply oscillation frequency according to claim 1, characterized in that, The diode circuit includes: The first diode has its anode connected to the DC voltage input port; and, The anode of the second diode is connected to the cathode of the first diode and one terminal of the energy storage capacitor.

3. The charge pump boost circuit with adjustable single-power-supply oscillation frequency according to claim 2, characterized in that, The oscillator includes: The first resistor has one end connected to the DC voltage input port; The third resistor has one end connected to the DC voltage input port; The first NMOS transistor has its drain connected to the other end of the first resistor and its source connected to reference ground. The second resistor has one end connected to the drain of the first NMOS transistor and the other end connected to the gate of the first NMOS transistor. The first capacitor has one terminal connected to the drain of the first NMOS transistor; The second capacitor has one terminal connected to the gate of the first NMOS transistor. The fourth resistor has one end connected to the other terminal of the second capacitor and the other end of the third resistor; and, The drain of the second NMOS transistor is connected to the other end of the third resistor and the other end of the energy storage capacitor, and its gate is connected to the other end of the fourth resistor and the other end of the first capacitor. Its source is connected to the reference ground.

4. The charge pump boost circuit with adjustable single-power-supply oscillation frequency according to claim 3, characterized in that, The oscillator generates two AC oscillation voltages with adjustable frequencies specifically by determining the oscillation frequency through the selection of parameters for the first resistor, second resistor, third resistor, fourth resistor, first capacitor, and second capacitor, and generating two AC oscillation voltages at the determined oscillation frequency in the following manner: From the initial state to time t0, the first NMOS transistor is turned on and the second NMOS transistor is turned off. The voltage at the connection point between the anode of the second diode and the cathode of the first diode and one terminal of the energy storage capacitor is the sum of the input DC voltage and the drain voltage of the second NMOS transistor, minus the forward voltage drop of the first diode. From time t0 to time t1, the first NMOS transistor is turned off and the second NMOS transistor is turned on. The voltage at the connection point between the anode of the second diode and the cathode of the first diode and one terminal of the energy storage capacitor is the difference between the input DC voltage and the forward conduction voltage drop of the first diode.

5. A charge pump boost circuit with adjustable single-supply oscillation frequency according to any one of claims 1 to 4, characterized in that, The load is connected between the output of the diode circuit and the reference ground.

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