A high-voltage output controllable charge pump power supply system

Abstract

The application provides a charge pump power supply system with controllable high-voltage output, and belongs to the technical field of power management.The charge pump power supply system introduces a resistance feedback modulation module and a digital control circuit matched with the resistance feedback modulation module on the basis of a conventional charge circuit, utilizes the switching characteristics of a transmission gate to accurately control the size of output feedback, and then controls the pulse width variation of oscillation of an oscillator to achieve the purpose of controlling output voltage, simplifies the modulation circuit, improves the integration of the charge pump modulation circuit, greatly reduces the overall power consumption on the basis of maintaining the performance and functions of the charge pump.The application improves the controllability of the charge pump power supply circuit and enriches the application mode of the charge pump circuit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power management, and relates to a charge pump power supply system with controllable high-voltage output, which can be applied to a power module of a speed sensor, used for providing stable power supply voltage for other circuits, and capable of outputting adjustable voltage according to the requirements of the powered circuit, simplifying the circuit structure and reducing the cost. BACKGROUND

[0002] With the gradual entry of smart phones and ultra-thin tablet computers and other mobile devices into millions of households, size, power consumption and controllability gradually become important indicators for evaluating the advantages and disadvantages of a mobile device. Therefore, under the premise of realizing functions and performance, how to reduce the power consumption of the circuit and improve the controllability has become a problem to be solved. As an extremely important heart part in the circuit, the power management circuit is the main development direction of high integration and high controllability in vehicle-mounted and handheld mobile devices. Among many power management circuits, the LDO (Low Dropout Regulaor) can only generate a voltage lower than the power supply voltage, the inductance energy storage DC-DC (Direct Current-Direct Current) converter has poor anti-electromagnetic interference performance due to the existence of inductance, and the external circuit is relatively complex, which is not convenient for size reduction and high integration; and the charge pump does not have the above problems. The charge pump has the advantages of low electromagnetic interference, simple peripheral circuit, and high voltage in theory through the increase of the number of stages, and since its advent, it has been a regular of power management circuit research, and is very common in high-voltage application occasions.

[0003] The traditional charge pump circuit often adopts a fixed output voltage mode, and the voltage is only related to the number of stages, which is often set at the beginning of the design, and the controllability of the charge pump as a pure analog circuit is poor, which will limit the application of the circuit and cannot meet the adjustable power supply voltage required by the powered circuit due to the change of the working state in the current diversified circuit design environment of the power supply circuit, and the traditional charge pump voltage modulation circuit often uses PWM (Pulse Width Modulation) and PFM (Pulse Frequency Modulation) modulation mode, which is relatively complex and requires more circuits, which makes the integration of the charge pump poor, and thus some additional circuit power consumption is also brought. Therefore, the charge pump circuit can combine the charge pump circuit and the digital circuit, and the output voltage of the charge pump circuit can be adjusted through the adjustable programmable characteristics and the characteristics of realizing complex operation of the digital circuit; at the same time, the combination with the digital circuit brings different possibilities for the charge pump circuit, and simplifies the overall modulation circuit, so that the charge pump realizes stable power supply with the least circuit, improves the integration, reduces the overall power consumption, and increases the practicability of the circuit. SUMMARY

[0004] In order to solve the above problems in the prior art, the application provides a high-voltage output controllable charge pump power supply system, which introduces a resistance feedback modulation module and a digital control circuit matched therewith on the basis of a traditional charge circuit, utilizes the switching characteristics of a transmission gate to accurately control the size of the output feedback, and then controls the pulse width variation of the oscillator to achieve the purpose of controlling the output voltage, and simplifies the modulation circuit, improves the integration of the charge pump modulation circuit, greatly reduces the overall power consumption on the basis of maintaining the performance and function of the charge pump.

[0005] In order to achieve the above functions, the technical scheme of the application is as follows:

[0006] A high-voltage output controllable charge pump power supply system comprises a resistance feedback array, an error amplifier, a voltage comparator, a digital control circuit, a charge pump circuit and a clock generating circuit.

[0007] The resistance feedback array is connected in series by a variable resistance array and a fixed resistance, the fixed resistance is an ordinary resistance, the variable resistance is connected in parallel by a transmission gate switch and a resistance, and the variable resistance array is connected in series by a plurality of variable resistances, and the size of the variable resistance array resistance is determined by the switching characteristics of the transmission gate.

[0008] The digital control circuit is programmed by Verilog HDL (Hardware Description Language) and has operation control function. The error amplifier adopts a folded common-gate common-source structure; the voltage comparator adopts a hysteresis comparator structure; the clock generation circuit adopts a ring oscillator, frequency divider and non-overlapping clock structure. The charge pump circuit adopts a cross-coupled charge pump structure, which, in cooperation with the non-overlapping clock, can improve the pumping efficiency as much as possible under high integration.

[0009] The digital control circuit is connected with the variable resistance array of the resistance feedback array. After the digital control circuit performs a fitting operation on the working state and temperature of the powered system, the variable resistance array of the resistance feedback array is controlled to change the feedback ratio of the resistance feedback array and the size of the feedback voltage. The sampling output end of the resistance feedback array is connected with the negative end of the error amplifier, and the error amplifier compares the feedback voltage and the reference voltage and generates an error amplification signal. The output end of the error amplifier is connected with the clock generation circuit, and the error amplification signal generated by the error amplifier is used to correct the clock pulse with different duty cycles generated by the control clock generation circuit. The clock generation circuit is connected with the charge pump circuit, and the working state of the charge pump circuit is controlled by the clock pulse with different duty cycles, so as to finally control the output voltage of the charge pump. The voltage comparator is connected with the digital control circuit, and the voltage comparator generates the working state signal of the charge pump by comparing the size of the feedback voltage and the reference voltage, and transmits the working state signal to the digital control circuit, so that the powered system can start to work after the voltage of the charge pump is stabilized.

[0010] Compared with the prior art, the beneficial effects of the present application are as follows:

[0011] (1) The supply voltage of the charge pump circuit is controlled by the digital circuit, which improves the controllability of the charge pump supply circuit and enriches the application mode of the charge pump circuit.

[0012] (2) The structure of the charge pump modulation circuit is simplified, the integration degree of the circuit is improved, and the stability and practicability of the circuit are improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a circuit system structure diagram of the present application.

[0014] Figure 2 It is a resistance feedback array structure schematic diagram provided by the present application.

[0015] Figure 3 It is an output stable charge pump circuit structure schematic diagram provided by the present application. DETAILED DESCRIPTION

[0016] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and technical solutions.

[0017] like Figure 1 As shown, a low-power, controllable charge pump power supply system includes a resistive feedback array, an error amplifier, a voltage comparator, a digital control circuit, a charge pump circuit, and a clock generation circuit. The resistive feedback array feeds a feedback voltage Vf to the inverting terminal of the error amplifier. The error amplifier amplifies the error between Vf and the reference voltage VREF, and the output voltage serves as the enable terminal of the clock generation circuit, determining whether to generate a clock signal, and thus whether the charge pump operates, ultimately controlling the charge pump's output voltage. Furthermore, the feedback voltage Vf is compared with the reference voltage VREF by the voltage comparator. The comparison result is then passed to the digital control circuit, which outputs an enable signal to subsequent circuits (not shown in the figure). This ensures that other powered circuits only begin operating after the charge pump has finished charging.

[0018] like Figure 2 The diagram shows a resistive feedback array structure provided by this invention. The resistive feedback array includes a fixed resistor Rf and a variable resistor array Rx consisting of five series-connected variable resistors (the transmission gate switch and the resistor are connected in parallel). The variable resistor array controls the resistance value of the variable resistor array Rx by controlling the transmission gate switch of the variable resistors through a digital control circuit, thereby controlling the feedback ratio of the output voltage VCP. Assuming the fixed resistor Rf is 4R, the resistances in the variable resistor array Rx are R, 2R, 4R, 2R, and R. Thus, by opening and closing the transmission gate switch, precise control of the resistance ratio for various targets can be achieved. Its voltage division principle is as follows:

[0019]

[0020] Where Vf is the feedback voltage, VCP is the output voltage of the entire charge pump power supply system, Rx is the total resistance of the variable sampling resistor, and Rf is the fixed resistor.

[0021] like Figure 3As shown, the application provides an output stable charge pump circuit structure schematic diagram, the charge pump circuit will generate a higher output voltage VCP than the input through frequent charge transfer, and when the charge pump loses the clock signal, it will stop working, thereby reducing the circuit power consumption, improving the working efficiency of the charge pump. The charge pump circuit includes 8 NMOS transistors (MN1, MN2, MN3, MN4, MN5, MN6, MN7, MN8), 8 PMOS transistors (MP1, MP2, MP3, MP4, MP5, MP6, MP7, MP8) and 8 flying capacitors (C1, C2, C3, C4, C5, C6, C7, C8). It can be divided into four identical voltage doublers. Take the first stage as an example (MN1, MN2, MP1, MP2, C1, C2 form a voltage doubler), wherein MN1, MN2, MP1 and MP2 are connected as switches according to the cross-coupled connection mode, MN1 and MP1 source level are connected to each other and intersect at A1 point, and the two ends of capacitor C1 are connected to clock signal CLK and A1 point respectively; MN2 and MP2 source level are connected to each other and intersect at B1 point, and the two ends of capacitor C2 are connected to clock signal ~CLK and B1 point respectively; the drain level of MN1 and the drain level of MN2 are connected, the drain level of MP1 and the drain level of MP2 are connected, the gate of MN1 and MP1 is connected to B1 point, and the gate of MN2 and MP2 is connected to A1 point, finally forming a cross-coupled mechanism. Four voltage doublers are connected in turn, the left end of the first stage is connected to the input voltage VDD, and the right end of the last stage is connected to the output voltage VCP. Because the transistors are used as switches, the width-length ratio of PMOS transistors is twice that of NMOS transistors, and the size of the capacitor also needs to be considered comprehensively.

[0022] The working principle of the charge pump circuit is as follows:

[0023] The working principle of the charge pump circuit is the transfer and superposition of charges, so according to the law of conservation of charge:

[0024] Q (1) = Q (2)

[0025] The final output voltage of the circuit is derived step by step. It is assumed that in the first switching stage, CLK is high and CLK is low, and in the second switching stage, CLK is low and CLK is high. Charge analysis can be divided into four steps to simulate the charge process from input to output:

[0026] Step i) Charge transfer between capacitors C1 and C4;

[0027] Step ii) Charge transfer between capacitors C4 and C5;

[0028] Step iii) Charge transfer between capacitors C5 and C8;

[0029] Step iv) Charge transfer between C8 and load capacitor COUT (not labeled in the figure).

[0030] So the charge balance analysis for the first stage of CLK is given as:

[0031]

[0032] Let C1 = C4 = C, we have

[0033]

[0034] where, V1 represents the voltage output of the first voltage doubler on the left. V2 represents the voltage output of the second voltage doubler on the left.

[0035] Step ii) Charge balance analysis between C4 and C5:

[0036]

[0037] Let C4 = C5 = C, we have

[0038]

[0039] where, V3 represents the voltage output of the third voltage doubler on the left.

[0040] Step iii) Charge balance analysis between C5 and C8:

[0041]

[0042] Let C5 = C8 = C, we have

[0043]

[0044] where, VCP represents the output voltage of the whole circuit.

[0045] Step iv) Charge balance analysis between C8 and COUT:

[0046]

[0047] Let C8 = COUT = C, we have the final formula for the output voltage

[0048]

[0049] where, I L is the load current of the charge pump, f is the working frequency of the circuit, C is the capacitance value of the flying capacitor, how to balance the performance of the charge pump circuit, in the above formula has a clear quantitative.

Claims

1. A high-voltage output controllable charge pump power supply system, characterized in that, The system includes a resistor feedback array, an error amplifier, a voltage comparator, a digital control circuit, a charge pump circuit, and a clock generation circuit; The aforementioned resistor feedback array consists of a variable resistor array and a fixed resistor connected in series; wherein, the variable resistor is formed by a transmission gate switch and a resistor connected in parallel, and the variable resistor array is formed by several variable resistors connected in series. The resistance of the variable resistor array is determined by utilizing the switching characteristics of the transmission gate. The digital control circuit is connected to the variable resistor array of the resistive feedback array. After performing a fitting calculation on the operating state and temperature of the powered system, the digital control circuit controls the variable resistor array of the resistive feedback array to change the feedback ratio of the resistive feedback array, thereby changing the magnitude of the feedback voltage. The sampling output terminal of the resistive feedback array is connected to the negative terminal of the error amplifier. The error amplifier compares the feedback voltage and the reference voltage and generates an error amplification signal. The output terminal of the error amplifier is connected to the clock generation circuit. The error amplification signal generated by the error amplifier is used to correct the clock pulses generated by the clock generation circuit with different duty cycles. The clock generation circuit is connected to the charge pump circuit. The clock pulses with different duty cycles control the operating state of the charge pump circuit, ultimately controlling the output voltage of the charge pump. The voltage comparator is connected to the digital control circuit. The voltage comparator generates the operating state signal of the charge pump by comparing the magnitude of the feedback voltage and the reference voltage, and transmits it to the digital control circuit. After the charge pump voltage stabilizes, the powered system starts to work.

2. The high-voltage output controllable charge pump power supply system according to claim 1, characterized in that, The digital control circuit is generated by Verilog HDL programming and has arithmetic control functions; the error amplifier adopts a folded common-gate common-source structure; the voltage comparator adopts a hysteresis comparator structure; the clock generation circuit adopts a ring oscillator, frequency divider and non-overlapping clock structure; the charge pump circuit adopts a cross-coupled charge pump structure.

3. A high-voltage output controllable charge pump power supply system according to claim 1 or 2, characterized in that, The charge pump circuit includes 8 NMOS transistors, 8 PMOS transistors, and 8 flying capacitors; the 8 NMOS transistors are MN1, MN2, MN3, MN4, MN5, MN6, MN7, and MN8; the 8 PMOS transistors are MP1, MP2, MP3, MP4, MP5, MP6, MP7, and MP8; and the 8 flying capacitors are C1, C2, C3, C4, C5, C6, C7, and C8. The charge pump circuit consists of four identical voltage multipliers. MN1, MN2, MP1, MP2, C1, and C2 form the first-stage voltage multiplier. In the first-stage voltage multiplier, MN1, MN2, MP1, and MP2 are connected as switches in a cross-coupled configuration. The sources of MN1 and MP1 are interconnected at point A1, and the two ends of capacitor C1 are connected to the clock signal CLK and point A1, respectively. The sources of MN2 and MP2 are interconnected at point B1, and the two ends of capacitor C2 are connected to the clock signal CLK and point B1, respectively. The drains of MN1 and MN2 are connected, as are the drains of MP1 and MP2. The gates of MN1 and MP1 are connected to point B1, and the gates of MN2 and MP2 are connected to point A1, thus forming a cross-coupled mechanism. The four voltage multipliers are connected sequentially. The left end of the first-stage voltage multiplier is connected to the input voltage VDD, and the right end of the last-stage voltage multiplier is connected to the output voltage VCP.

4. The high-voltage output controllable charge pump power supply system according to claim 3, characterized in that, The aspect ratio of the PMOS transistor is twice that of the NMOS transistor.

5. A high-voltage output controllable charge pump power supply system according to claim 1, 2, or 4, characterized in that, The aforementioned resistance feedback array includes a fixed resistor Rf and a variable resistor array Rx consisting of five series-connected variable resistors. The variable resistor array uses a digital control circuit to control the transmission gate switch of the variable resistors, thereby controlling the resistance value of the variable resistor array Rx and consequently the feedback ratio of the output voltage VCP. Assuming the fixed resistor Rf is 4R, the resistances in the variable resistor array Rx are R, 2R, 4R, 2R, and R. By opening and closing the transmission gate switch, precise control of the resistance ratio for various targets can be achieved. Its voltage division principle is as follows: Where Vf is the feedback voltage, VCP is the output voltage of the entire charge pump power supply system, Rx is the total resistance of the variable sampling resistor, and Rf is the fixed resistor.

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