Low-ripple charge pump circuit, method and device based on current-controlled oscillator

Abstract

The invention discloses a low-ripple charge pump circuit, method and equipment based on a current control oscillator, and the circuit comprises a charge pump core unit, the clock input end of the charge pump core unit receives a clock signal, and the output end of the charge pump core unit generates pumping voltage; the input end of the voltage and current conversion unit is connected to the output end of the charge pump core unit, and the voltage and current conversion unit is used for converting the pumping voltage into first current; the current synthesis unit is used for receiving a reference current and the first current to obtain a control current; the control input end of the current control oscillator receives the control current, and the output end of the current control oscillator generates the clock signal; the oscillation frequency of the current control oscillator is in direct proportion to the control current; according to the charge pump circuit, continuous frequency modulation can be realized, so that the output ripple and electromagnetic interference are remarkably reduced, and the control precision of the output voltage is improved at the same time.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to a low-ripple charge pump circuit, method, and device based on a current-controlled oscillator. Background Technology

[0002] In integrated circuits, charge pumps are widely used to generate stable voltages that are either higher or lower than the supply voltage. Figure 1 This demonstrates a commonly used charge pump voltage control method. Its basic working principle is: using a voltage comparator, the output voltage (Vcpout) of the charge pump is compared with a reference voltage (Vref).

[0003] When the output voltage is higher than the reference voltage, the voltage comparator outputs a control signal to stop the charge pump. At this time, the output voltage begins to drop due to load consumption. When the output voltage drops below a certain threshold value of the reference voltage, the voltage comparator outputs a control signal again to resume the charge pump's operation. The main feature of this control method is that the operating state (operating or stopped) of the charge pump is determined by the result of voltage comparison, and this state is used to control whether a fixed-frequency clock signal is provided to the charge pump.

[0004] However, this existing charge pump control method has obvious defects and shortcomings: Poor control precision: To ensure system stability and avoid frequent switching near the critical point, the voltage comparator must have a hysteresis window. This hysteresis window directly leads to increased output voltage error, making precise voltage control impossible.

[0005] Large output ripple and severe electromagnetic interference (EMI): The charge pump generates abrupt current changes when switching between operating (clock on) and non-operating (clock off) states. This "bang-bang" (switching) control leads to significant output voltage ripple. Simultaneously, these periodic, abrupt current pulses generate significant electromagnetic interference, affecting the normal operation of other circuits within the system and reducing the overall system signal-to-noise ratio.

[0006] There is a need in the field for a charge pump solution that can improve control accuracy, reduce output ripple, and reduce electromagnetic interference. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to propose a charge pump circuit based on a current-controlled oscillator, which can realize continuous frequency modulation, thereby significantly reducing output ripple and electromagnetic interference, while improving the control accuracy of output voltage.

[0008] To solve the above-mentioned technical problems, the present invention provides a low-ripple charge pump circuit based on a current-controlled oscillator, characterized in that it includes: The core unit of the charge pump receives a clock signal at its clock input and generates a pump boost voltage at its output. A voltage-to-current conversion unit, whose input terminal is connected to the output terminal of the charge pump core unit, is used to convert the pumped voltage into a first current. A current synthesis unit is used to receive a reference current and a first current, and to subtract the reference current from the first current to obtain a control current; A current-controlled oscillator receives the control current at its control input terminal and generates the clock signal at its output terminal; the oscillation frequency of the current-controlled oscillator is proportional to the control current.

[0009] Preferably, the voltage-to-current conversion unit includes a MOS transistor, the pump-up voltage is connected to the gate of the MOS transistor, and the drain current of the MOS transistor constitutes the first current. Preferably, the current synthesis unit performs the subtraction operation between the reference current and the first current through a current mirror structure.

[0010] Preferably, the charge pump circuit constitutes a negative feedback closed-loop control system; when the pump-up voltage increases, the first current increases, the control current decreases, and the output frequency of the current-controlled oscillator decreases, thereby causing the pump-up voltage to decrease; when the pump-up voltage decreases, the first current decreases, the control current increases, and the output frequency of the current-controlled oscillator increases, thereby causing the pump-up voltage to rise again.

[0011] Preferably, the average value of the pump-up voltage is set by the value of the reference current.

[0012] To address the aforementioned technical problems, this invention also discloses a voltage control method for a charge pump, comprising the following steps: The output voltage of the charge pump is converted into a first current; The control current is obtained by subtracting the fixed reference current from the first current. A clock signal proportional to the control current is generated based on the control current. The charge pump is driven by the clock signal.

[0013] Preferably, the step of converting the output voltage of the charge pump into a first current is implemented by a voltage-to-current conversion circuit, wherein the output voltage is applied to the gate of a MOS transistor, and the drain current of the MOS transistor is used as the first current.

[0014] Preferably, the method constitutes a negative feedback closed-loop control process; when the output voltage increases, the first current increases, the control current decreases, and the frequency of the clock signal decreases, thereby causing the output voltage to decrease; when the output voltage decreases, the first current decreases, the control current increases, and the frequency of the clock signal increases, thereby causing the output voltage to rise again.

[0015] Preferably, the average value of the output voltage is set by setting the value of the reference current.

[0016] To address the aforementioned technical problems, the present invention also discloses an electronic device, including the low-ripple charge pump circuit based on a current-controlled oscillator described above.

[0017] With the above circuitry, a low-ripple charge pump circuit based on a current-controlled oscillator includes: a charge pump core unit, whose clock input receives a clock signal and whose output generates a pump boost voltage; a voltage-to-current conversion unit, whose input is connected to the output of the charge pump core unit, for converting the pump boost voltage into a first current; a current synthesis unit, for receiving a reference current and the first current, and subtracting the reference current from the first current to obtain a control current; and a current-controlled oscillator, whose control input receives the control current and whose output generates the clock signal; the oscillation frequency of the current-controlled oscillator is proportional to the control current. Compared with the prior art, the present invention has the following significant advantages: Significantly reduced output ripple and electromagnetic interference (EMI): This invention abandons the traditional "switching" control and adopts continuous frequency modulation. The charge pump clock frequency changes smoothly according to the load and output voltage conditions, avoiding sudden changes in current, thereby greatly reducing output voltage ripple and effectively reducing the resulting electromagnetic interference.

[0018] Improved circuit signal-to-noise ratio: Due to the reduction of ripple and noise, the quality of the charge pump power supply is improved, which is beneficial to improving the performance and signal-to-noise ratio of subsequent circuits that rely on this power supply (such as analog circuits and radio frequency circuits).

[0019] High control precision: This solution does not require setting a voltage hysteresis window. It achieves voltage regulation through precise addition and subtraction of current and continuous adjustment of frequency, which theoretically can achieve higher output voltage control precision.

[0020] Compact structure and easy integration: The entire control loop is mainly composed of basic analog circuit modules such as current mirror, voltage-to-current converter and current-controlled oscillator, which is very suitable for monolithic integration on standard CMOS process. Attached Figure Description

[0021] Figure 1This is a circuit block diagram of a charge pump voltage control method commonly used in the background art; Figure 2 This is the overall circuit diagram of the low-ripple charge pump circuit based on a current-controlled oscillator of the present invention; Figure 3 This is a circuit diagram of a specific embodiment of the voltage-to-current conversion unit used to generate current I1 in this invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Example

[0024] Please see Figure 2 This invention discloses a low-ripple charge pump circuit based on a current-controlled oscillator, comprising: The core unit of the charge pump receives a clock signal at its clock input and generates a pump boost voltage at its output. A voltage-to-current conversion unit, whose input terminal is connected to the output terminal of the charge pump core unit, is used to convert the pumped voltage into a first current. A current synthesis unit is used to receive a reference current and a first current, and to subtract the reference current from the first current to obtain a control current; A current-controlled oscillator receives the control current at its control input terminal and generates the clock signal at its output terminal; the oscillation frequency of the current-controlled oscillator is proportional to the control current. Example

[0025] This embodiment is based on Embodiment 1. In this embodiment, the voltage-to-current conversion unit includes a MOS transistor, the pump-up voltage is connected to the gate of the MOS transistor, and the drain current of the MOS transistor constitutes the first current. Example

[0026] This embodiment is based on Embodiment 1. In this embodiment... The charge pump core unit can adopt a voltage doubler charge pump structure known in the art (such as the Dickson structure), and its function is to pump the input voltage to the required output voltage Vcpout under the drive of the clock CP_CLK.

[0027] Please see Figure 3A specific implementation of the voltage-to-current conversion unit can be a common-source MOS transistor xM. The output voltage Vcpout is connected to the gate of transistor xM, and the source of transistor xM is biased through a resistor or a constant current source (not fully shown in the figure). Its drain current is I1. By properly designing the transistor size and bias, I1 can maintain a good linear or predetermined relationship with Vcpout.

[0028] The current synthesis unit uses a current mirror structure to perform the subtraction operation between the reference current and the first current. For example, a PMOS current mirror is used to generate a reference current Iref, and I1 is used as the discharge current. The net current flowing through the output branch of the current mirror is the control current Ictrl = Iref - I1.

[0029] The current-controlled oscillator can adopt a ring oscillator structure, in which the bias current or charge / discharge current of its delay unit is provided by the control current Ictrl, so that the oscillation frequency is proportional to Ictrl.

[0030] In practical applications, the reference current Iref can be generated by a bandgap reference voltage source to ensure its stability and accuracy.

[0031] The entire system forms a negative feedback loop, automatically adjusting the clock frequency to stabilize the output voltage Vcpout near the target value set by Iref, thus achieving smooth and low-noise voltage regulation.

[0032] The charge pump circuit constitutes a negative feedback closed-loop control system; when the pump-up voltage increases, the first current increases, the control current decreases, and the output frequency of the current-controlled oscillator decreases, thereby causing the pump-up voltage to decrease; when the pump-up voltage decreases, the first current decreases, the control current increases, and the output frequency of the current-controlled oscillator increases, thereby causing the pump-up voltage to rise again.

[0033] The average value of the pump-up voltage is set by the value of the reference current. Example

[0034] This embodiment discloses a voltage control method for a charge pump applied to the circuit described in Embodiment 1, comprising the following steps: The output voltage of the charge pump is converted into a first current; The control current is obtained by subtracting the fixed reference current from the first current. A clock signal proportional to the control current is generated based on the control current. The charge pump is driven by the clock signal. Example

[0035] This embodiment is based on Embodiment 4. The step of converting the output voltage of the charge pump into a first current is achieved by a voltage-to-current conversion circuit, wherein the output voltage is applied to the gate of a MOS transistor, and the drain current of the MOS transistor is used as the first current.

[0036] The method constitutes a negative feedback closed-loop control process; when the output voltage increases, the first current increases, the control current decreases, and the frequency of the clock signal decreases, thereby causing the output voltage to drop; when the output voltage decreases, the first current decreases, the control current increases, and the frequency of the clock signal increases, thereby causing the output voltage to rise again.

[0037] The average value of the output voltage is set by setting the value of the reference current. Example

[0038] This embodiment discloses an electronic device, including a low-ripple charge pump circuit based on a current-controlled oscillator as described in any one of Embodiments 1 to 4. This low-ripple charge pump circuit based on a current-controlled oscillator significantly reduces output ripple and electromagnetic interference (EMI), abandoning traditional "switching" control and employing continuous frequency modulation. The charge pump clock frequency smoothly varies according to load and output voltage conditions, avoiding sudden current changes, thereby greatly reducing output voltage ripple and effectively reducing the resulting EMI. Due to the reduction in ripple and noise, the quality of the charge pump power supply is improved, which is beneficial to improving the performance and signal-to-noise ratio of subsequent circuits (such as analog circuits and RF circuits) that rely on this power supply. There is no need to set a voltage hysteresis window; voltage regulation is achieved through precise current addition and subtraction and continuous frequency adjustment, which theoretically can achieve higher output voltage control accuracy. The entire control loop is mainly composed of basic analog circuit modules such as a current mirror, a voltage-to-current converter, and a current-controlled oscillator, making it very suitable for monolithic integration on standard CMOS technology. It should be understood that the above are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A low-ripple charge pump circuit based on a current-controlled oscillator, characterized in that, include: The core unit of the charge pump receives a clock signal at its clock input and generates a pump boost voltage at its output. A voltage-to-current conversion unit, whose input terminal is connected to the output terminal of the charge pump core unit, is used to convert the pumped voltage into a first current. A current synthesis unit is used to receive a reference current and a first current, and to subtract the reference current from the first current to obtain a control current; A current-controlled oscillator receives the control current at its control input terminal and generates the clock signal at its output terminal; the oscillation frequency of the current-controlled oscillator is proportional to the control current.

2. The low-ripple charge pump circuit based on a current-controlled oscillator according to claim 1, characterized in that, The voltage-to-current conversion unit includes a MOS transistor, the pump-up voltage is connected to the gate of the MOS transistor, and the drain current of the MOS transistor constitutes the first current.

3. The low-ripple charge pump circuit based on a current-controlled oscillator according to claim 1, characterized in that, The current synthesis unit uses a current mirror structure to perform the subtraction operation between the reference current and the first current.

4. The low-ripple charge pump circuit based on a current-controlled oscillator according to claim 1, characterized in that, The charge pump circuit constitutes a negative feedback closed-loop control system; when the pump-up voltage increases, the first current increases, the control current decreases, and the output frequency of the current-controlled oscillator decreases, thereby causing the pump-up voltage to decrease; when the pump-up voltage decreases, the first current decreases, the control current increases, and the output frequency of the current-controlled oscillator increases, thereby causing the pump-up voltage to rise again.

5. The low-ripple charge pump circuit based on a current-controlled oscillator according to claim 1, characterized in that, The average value of the pump-up voltage is set by the value of the reference current.

6. A voltage control method for a charge pump applied to the circuit of claim 1, characterized in that, Includes the following steps: The output voltage of the charge pump is converted into a first current; The control current is obtained by subtracting the fixed reference current from the first current. A clock signal proportional to the control current is generated based on the control current. The charge pump is driven by the clock signal.

7. The voltage control method for a charge pump according to claim 6, characterized in that, The step of converting the output voltage of the charge pump into a first current is achieved by a voltage-to-current conversion circuit, wherein the output voltage is applied to the gate of a MOS transistor, and the drain current of the MOS transistor is used as the first current.

8. The voltage control method for a charge pump according to claim 6, characterized in that, The method constitutes a negative feedback closed-loop control process; when the output voltage increases, the first current increases, the control current decreases, and the frequency of the clock signal decreases, thereby causing the output voltage to drop; when the output voltage decreases, the first current decreases, the control current increases, and the frequency of the clock signal increases, thereby causing the output voltage to rise again.

9. The voltage control method for a charge pump according to claim 6, characterized in that, The average value of the output voltage is set by setting the value of the reference current.

10. An electronic device, characterized in that, Includes a low-ripple charge pump circuit based on a current-controlled oscillator as described in any one of claims 1 to 5.

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