Patent Publication Number: US-2023155494-A1

Title: Switched capacitor voltage converter

Description:
CROSS REFERENCE TO THE RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 202111337104.8, filed on Nov. 12, 2021, which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present application belongs to the field of switching power supply, and particularly relates to a switched capacitor voltage converter. 
     BACKGROUND 
     Dickson switched capacitor voltage converter has a basic power conversion structure and is widely used in a variety of power management applications to convert one direct current (DC) voltage to another DC voltage and output. 
       FIG.  1    shows a conventional Dickson 4:1 switched capacitor voltage converter, a branch A of a circuit of the Dickson 4:1 switched capacitor voltage converter transfers electric charges from an input terminal to an output terminal via a first switch transistor Q 1 A -an eighth switch transistor Q 8 A, a first capacitor CF 1 A, a second capacitor CF 2 A and a third capacitor CF 3 A. In the same way, a branch B of the Dickson 4:1 switched capacitor voltage converter transfers electric charges from the input terminal to the output terminal via a ninth switch transistor Q 1 B- a  sixteenth switch transistor Q 8 B, a fourth capacitor CF 1 B, a fifth capacitor CF 2 B and a sixth capacitor CF 3 B, so as to finally realize an output voltage VOUT=VIN/4 and an output current IOUT=4 ∗ IIN. 
     Conversion efficiency is an important index of a switched capacitor voltage converter, the conversion efficiency determines a load capacity and temperature rise of the switched capacitor voltage converter. The higher the conversion efficiency, the greater the load capacity of the switched capacitor voltage converter and the lower the temperature rise. The main losses of the switched capacitor voltage converter come from: 1) Conduction loss of each switch transistor in the circuit; 2) Switching loss when each switch transistor is switched; 3) Driving loss of each switch transistor. A key to improving the conversion efficiency is how to reduce the above-mentioned losses. The switching loss is proportional to the voltage difference between both terminals of each switch transistor when switched, and the greater the voltage difference, the greater the switching loss. Therefore, the current switched capacitor voltage converter has problems of low conversion efficiency and large switching loss, which limits the conversion efficiency of the switched capacitor voltage converters. 
     SUMMARY 
     In order to overcome the above-mentioned problems, and particularly to the switching loss, embodiments of the present application provide a switched capacitor voltage converter, a voltage difference between both terminals of each switch transistor when switched is decreased to be close to zero or is zero, thereby reducing switching loss and improving conversion efficiency. 
     In order to solve the above-mentioned problems, an inductor and several switch transistors are added between two branches of a conventional Dickson switched capacitor voltage converter to obtain the switched capacitor voltage converter of embodiments of the present application, in the switched capacitor voltage converter of the embodiments of the present application, by controlling the turning on and off of these switch transistors, an electric charge or electric charges on parasitic capacitors of one branch are completely transferred to another branch via the inductor within a short period of time after all the primary switch transistors are turned off, so that the voltage difference between both terminals of each of the primary switch transistors becomes zero, and then the primary switch transistors are started to be turned on, the voltage difference between both terminals of each of the primary switch transistors is zero at the moment when the primary switch transistors are turned on respectively, thereby reducing the switching loss of the switch transistors and improving the conversion efficiency of the switched capacitor voltage converter. 
     The technical solution of embodiments of the present application relates to a switched capacitor voltage converter, including an inductive branch and two branches, the two branches include a first branch and a second branch, and an input voltage, upon travelling via the two branches, is converted into another voltage and output. 
     The inductive branch is connected between the first branch and the second branch, and switch transistors in the first branch and the second branch are primary switch transistors. 
     The inductive branch is configured to transfer an electric charge or electric charges on parasitic capacitors of one branch to another branch of the two branches after all the primary switch transistors are turned off, so that a voltage difference between both terminals of each of the primary switch transistors becomes zero, and then the each of the primary switch transistors is turned on, the voltage difference between both terminals of the each of the primary switch transistors is zero at an instant when the each of primary switch transistors is turned on respectively. 
     Furthermore, the first branch includes a first switch transistor, a second switch transistor, a third switch transistor, a fourth switch transistor, a fifth switch transistor, a sixth switch transistor, a seventh switch transistor, an eighth switch transistor, a first capacitor, a second capacitor and a third capacitor; and the second branch includes a ninth switch transistor, a tenth switch transistor, an eleventh switch transistor, a twelfth switch transistor, a thirteenth switch transistor, a fourteenth switch transistor, a fifteenth switch transistor, a sixteenth switch transistor, a fourth capacitor, a fifth capacitor and a sixth capacitor. 
     A first terminal of the first switch transistor and a first terminal of the ninth switch transistor are connected an input terminal of the switched capacitor voltage converter, the input terminal is connected to an external input voltage, a second terminal of the first switch transistor is connected to a first terminal of the second switch transistor and a first terminal of the first capacitor, and a second terminal of the ninth switch transistor is connected to a first terminal of the tenth switch transistor and a first terminal of the fourth capacitor. 
     A second terminal of the second switch transistor is connected to a first terminal of the third switch transistor and a first terminal of the second capacitor, and a second terminal of the tenth switch transistor is connected to a first terminal of the eleventh switch transistor and a first terminal of the fifth capacitor. 
     A second terminal of the third switch transistor is connected to a first terminal of the fourth switch transistor and a first terminal of the third capacitor, and a second terminal of the eleventh switch transistor is connected to a first terminal of the twelfth switch transistor and a first terminal of the sixth capacitor. 
     A second terminal of the fourth switch transistor is connected to a first terminal of the fifth switch transistor and a first terminal of the seventh switch transistor, and a second terminal of the twelfth switch transistor is connected to a first terminal of the thirteenth switch transistor and a first terminal of the fifteenth switch transistor. 
     A second terminal of the fifth switch transistor is connected to a second terminal of the first capacitor, a second terminal of the third capacitor and a first terminal of the sixth switch transistor, a second terminal of the seventh switch transistor is connected to a second terminal of the second capacitor and a first terminal of the eighth switch transistor, and a second terminal of the sixth switch transistor and a second terminal of the eighth switch transistor are grounded. 
     A second terminal of the thirteenth switch transistor is connected to a second terminal of the fourth capacitor, a second terminal of the sixth capacitor and a first terminal of the fourteenth switch transistor, and a second terminal of the fifteenth switch transistor is connected to a second terminal of the fifth capacitor and a first terminal of the sixteenth switch transistor, and a second terminal of the fourteenth switch transistor and a second terminal of the sixteenth switch transistor are grounded. 
     The second terminal of the fourth switch transistor, the first terminal of the fifth switch transistor, the first terminal of the seventh switch transistor, the second terminal of the twelfth switch transistor, the first terminal of the thirteenth switch transistor and the first terminal of the fifteenth switch transistor are connected to an output terminal of the switched capacitor voltage converter. 
     Furthermore, the inductive branch includes a seventeenth switch transistor, an eighteenth switch transistor, a nineteenth switch transistor, a twentieth switch transistor, a twenty-first switch transistor, a twenty-second switch transistor and the inductor. 
     The second terminal of the first capacitor, the second terminal of the third capacitor, the second terminal of the fifth switch transistor and the first terminal of the sixth switch transistor are connected to a first connection point, and the second terminal of the second capacitor, the second terminal of the seventh switch transistor and the first terminal of the eighth switch transistor are connected to a second connection point. 
     The second terminal of the fourth capacitor, the second terminal of the sixth capacitor, the second terminal of the thirteenth switch transistor and the first terminal of the fourteenth switch transistor are connected to a third connection point, and the second terminal of the fifth capacitor, the second terminal of the fifteenth switch transistor and the first terminal of the sixteenth switch transistor are connected to a fourth connection point. 
     A first terminal of the seventeenth switch transistor is connected to the second connection point, a second terminal of the seventeenth switch transistor is connected to a first terminal of the inductor, a first terminal of the eighteenth switch transistor and a first terminal of the nineteenth switch transistor; a second terminal of the eighteenth switch transistor is grounded, and a second terminal of the nineteenth switch transistor is connected to the third connection point. 
     A second terminal of the inductor is connected to a first terminal of the twentieth switch transistor, a first terminal of the twenty-first switch transistor and a first terminal of the twenty-second switch transistor, and a second terminal of the twentieth switch transistor is connected to the fourth connection point; and a second terminal of the twenty-first switch transistor is grounded, and a second terminal of the twenty-second switch transistor is connected to the first connection point. 
     Furthermore, the first branch includes a first switch transistor, a second switch transistor, a third switch transistor, a fourth switch transistor, a fifth switch transistor, a sixth switch transistor, a seventh switch transistor, an eighth switch transistor, a first sub-switch transistor, a first capacitor, a second capacitor, a third capacitor and a first sub-capacitor; and the second branch includes a ninth switch transistor, a tenth switch transistor, an eleventh switch transistor, a twelfth switch transistor, a thirteenth switch transistor, a fourteenth switch transistor, a fifteenth switch transistor, a sixteenth switch transistor, a second sub-switch transistor, a fourth capacitor, a fifth capacitor, a sixth capacitor and a second sub-capacitor. 
     A first terminal of the first switch transistor and a first terminal of the ninth switch transistor are connected an input terminal of the switched capacitor voltage converter, the input terminal is connected to an external input voltage, a second terminal of the first switch transistor is connected to a first terminal of the second switch transistor and a first terminal of the first capacitor, and a second terminal of the ninth switch transistor is connected to a first terminal of the tenth switch transistor and a first terminal of the fourth capacitor. 
     A second terminal of the second switch transistor is connected to a first terminal of the third switch transistor and a first terminal of the second capacitor, a second terminal of the tenth switch transistor is connected to a first terminal of the eleventh switch transistor and a first terminal of the fifth capacitor, a second terminal of the third switch transistor is connected to a first terminal of the fourth switch transistor and a first terminal of the third capacitor, and a second terminal of the eleventh switch transistor is connected to a first terminal of the twelfth switch transistor and a first terminal of the sixth capacitor. 
     A second terminal of the fourth switch transistor is connected to a first terminal of the fifth switch transistor and a first terminal of the first sub-capacitor, a second terminal of the twelfth switch transistor is connected to a first terminal of the thirteenth switch transistor and a first terminal of the second sub-capacitor, a second terminal of the fifth switch transistor is connected to a first terminal of the sixth switch transistor and a first terminal of the eighth switch transistor, a second terminal of the sixth switch transistor is connected to a second terminal of the first sub-capacitor, a second terminal of the second capacitor and a first terminal of the seventh switch transistor, a second terminal of the eighth switch transistor is connected to a first terminal of the first sub-switch transistor, a second terminal of the first capacitor and a second terminal of the third capacitor, and a second terminal of the seventh switch transistor and a second terminal of the first sub-switch transistor are grounded. 
     A second terminal of the thirteenth switch transistor is connected to a first terminal of the fourteenth switch transistor and a first terminal of the sixteenth switch transistor, a second terminal of the fourteenth switch transistor is connected to a second terminal of the second sub-capacitor, a second terminal of the fifth capacitor and a first terminal of the fifteenth switch transistor, a second terminal of the sixteenth switch transistor is connected to a first terminal of the second sub-switch transistor, a second terminal of the fourth capacitor and a second terminal of the sixth capacitor, and a second terminal of the fifteenth switch transistor and a second terminal of the second sub-switch transistor are grounded. 
     The second terminal of the fifth switch transistor, the first terminal of the sixth switch transistor, the first terminal of the eighth switch transistor, the second terminal of the thirteenth switch transistor, the first terminal of the fourteenth switch transistor and the first terminal of the sixteenth switch transistor are connected to the output terminal of the switched capacitor voltage converter. 
     Furthermore, the second terminal of the first capacitor, the second terminal of the third capacitor, the second terminal of the eighth switch transistor and the first terminal of the first sub-switch transistor are connected to a first connection node; the second terminal of the second capacitor, the second terminal of the first sub-capacitor, the second terminal of the sixth switch transistor and the first terminal of the seventh switch transistor are connected to a second connection node; the second terminal of the fourth capacitor, the second terminal of the sixth capacitor, the second terminal of the sixteenth switch transistor and the first terminal of the second sub-switch transistor are connected to a third connection node; and the second terminal of the fifth capacitor, the second terminal of the second sub-capacitor, the second terminal of the fourteenth switch transistor and the first terminal of the fifteenth switch transistor are connected to a fourth connection node. 
     The first connection node is connected to a first terminal of the seventeenth switch transistor, a second terminal of the seventeenth switch transistor is connected to a first terminal of the inductor, a first terminal of the eighteenth switch transistor and a first terminal of the nineteenth switch transistor, a second terminal of the eighteenth switch transistor is grounded, and a second terminal of the nineteenth switch transistor is connected to the fourth connection node. 
     A second terminal of the inductor is connected to a first terminal of the twentieth switch transistor, a first terminal of the twenty-first switch transistor and a first terminal of the twenty-second switch transistor, a second terminal of the twentieth switch transistor is connected to the third connection node, a second terminal of the twenty-first switch transistor is grounded, and a second terminal of the twenty-second switch transistor is connected to the second connection node. 
     Furthermore, a first working cycle of the switched capacitor voltage converter includes four phases as follows. 
     A first phase: the first switch transistor, the third switch transistor, the fifth switch transistor, the eighth switch transistor, the tenth switch transistor, the twelfth switch transistor, the fourteenth switch transistor, the fifteenth switch transistor, the seventeenth switch transistor, the nineteenth switch transistor and the twenty-first switch transistor are turned on, and remaining switch transistors are turned off; the input voltage is connected to the output terminal via the first capacitor, the third capacitor is connected in series to the output terminal and then connected in parallel to the second capacitor, the sixth capacitor is connected in parallel to the output terminal, and the fifth capacitor is connected in series to the output terminal and then connected in parallel to the fourth capacitor; and a current on the inductor is zero. 
     A second phase: the seventeenth switch transistor, the nineteenth switch transistor, the twentieth switch transistor and the twenty-second switch transistor are turned on, and remaining switch transistors are turned off; the current on the inductor increases and then decreases until to zero, and the second phase ends when the current on the inductor decreases to zero. 
     A third phase: the second switch transistor, the fourth switch transistor, the sixth switch transistor, the seventh switch transistor, the ninth switch transistor, the eleventh switch transistor, the thirteenth switch transistor, the sixteenth switch transistor, the eighteenth switch transistor, the twentieth switch transistor and the twenty-second switch transistor are turned on, and remaining switch transistors are turned off; the third capacitor is connected in parallel to the output terminal, the second capacitor is connected in series to the output terminal and then connected in parallel to the first capacitor, the input voltage is connected to the output terminal via the fourth capacitor, and the sixth capacitor is connected in series to the output terminal and then connected in parallel to the fifth capacitor; and the current on the inductor is zero. 
     A fourth phase: the seventeenth switch transistor, the nineteenth switch transistor, the twentieth switch transistor and the twenty-second switch transistor are turned on, and remaining switch transistors are turned off; the current on the inductor increases and then decreases until to zero, and the fourth phase ends and the first phase starts when the inductive current decreases to zero. 
     Furthermore, a second working cycle of the switched capacitor voltage converter includes four phases as follows. 
     A first phase: the first switch transistor, the third switch transistor, the fifth switch transistor, the eighth switch transistor, the tenth switch transistor, the twelfth switch transistor, the fourteenth switch transistor, the fifteenth switch transistor, the eighteenth switch transistor and the twenty-first switch transistor are turned on, and remaining switch transistors are turned off; and the input voltage is connected to the output terminal via the first capacitor, the third capacitor is connected in series to the output terminal and then connected in parallel to the second capacitor, the sixth capacitor is connected in parallel to the output terminal, and the fifth capacitor is connected in series to the output terminal and then connected in parallel to the fourth capacitor; and a current on the inductor is zero. 
     A second phase: the seventeenth switch transistor, the nineteenth switch transistor, the twentieth switch transistor and the twenty-second switch transistor are turned on, and remaining switch transistors are turned off; the current on the inductor increases and then decreases until to zero, and the second phase ends when the current on the inductor decreases to zero. 
     A third phase: the second switch transistor, the fourth switch transistor, the sixth switch transistor, the seventh switch transistor, the ninth switch transistor, the eleventh switch transistor, the thirteenth switch transistor, the sixteenth switch transistor, the eighteenth switch transistor and the twenty-first switch transistor are turned on, and remaining switch transistors are turned off; and the third capacitor is connected in parallel to the output terminal, the second capacitor is connected in series to the output terminal and then connected in parallel to the first capacitor, the input voltage is connected to the output terminal via the fourth capacitor, and the sixth capacitor is connected in series to the output terminal and then connected in parallel to the fifth capacitor; and the current on the inductor is zero. 
     A fourth phase: the seventeenth switch transistor, the nineteenth switch transistor, the twentieth switch transistor and the twenty-second switch transistor are turned on, and remaining switch transistors are turned off; the current on the inductor increases and then decreases until to zero, the fourth phase ends and the first phase starts when the current on the inductor decreases to zero. 
     The inductor and the several switch transistors are added between two branches of a conventional Dickson switched capacitor voltage converter to obtain the switched capacitor voltage converter of the embodiments of the present application, in the switched capacitor voltage converter of the embodiments of the present application, by controlling the turning on and off of these switch transistors, the electric charges on the parasitic capacitors of one branch are completely transferred to another branch via the inductor during the dead time when all the primary switch transistors are turned off, thereby achieving zero voltage switching of all the primary switch transistors. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of a circuit structure of a conventional Dickson 4:1 switched capacitor voltage converter. 
         FIG.  2    is a schematic diagram of a circuit structure of a Dickson 4:1 switched capacitor voltage converter of an embodiment of the present application. 
         FIG.  3    is a first working sequence diagram of a Dickson 4:1 switched capacitor voltage converter of an embodiment of the present application. 
         FIG.  4    is a diagram showing a working state of a first phase in the first working sequence as shown in  FIG.  3   . 
         FIG.  5    is a diagram showing a working state of a second phase in the first working sequence as shown in  FIG.  3   . 
         FIG.  6    is a diagram showing a working state of a third phase in the first working sequence as shown in  FIG.  3   . 
         FIG.  7    is a diagram showing a working state of a fourth phase in the first working sequence as shown in  FIG.  3   . 
         FIG.  8    is a second working sequence diagram of a Dickson 4:1 switched capacitor voltage converter of an embodiment of the present application. 
         FIG.  9    is a diagram showing a working state of a first phase in the second working sequence as shown in  FIG.  8   . 
         FIG.  10    is a diagram showing a working state of a second phase in the second working sequence as shown in  FIG.  8   . 
         FIG.  11    is a diagram showing a working state of a third phase in the second working sequence as shown in  FIG.  8   . 
         FIG.  12    is a diagram showing a working state of a fourth phase in the second working sequence as shown in  FIG.  8   . 
         FIG.  13    is a schematic diagram of a circuit structure of a Dickson 5:1 switched capacitor voltage converter of another embodiment of the present application. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     To describe the technical solutions in embodiments of the present application more clearly, the following briefly describes the accompanying drawings required for describing the embodiments. It should be noted that, the embodiments of the present application and the features in the different embodiments may be combined with each other under the condition that they do not conflict with each other. 
       FIG.  2    is a schematic diagram of a circuit structure of a Dickson 4:1 switched capacitor voltage converter of an embodiment of the present application, the Dickson 4:1 switched capacitor voltage converter includes an inductive branch and two branches, and the two branches include a first branch and a second branch. 
     The first branch includes a first switch transistor Q 1 A, a second switch transistor Q 2 A, a third switch transistor Q 3 A, a fourth switch transistor Q 4 A, a fifth switch transistor Q 5 A, a sixth switch transistor Q 6 A, a seventh switch transistor Q 7 A, an eighth switch transistor Q 8 A, a first capacitor CF 1 A, a second capacitor CF 2 A and a third capacitor CF 3 A, and the second branch includes a ninth switch transistor Q 1 B, a tenth switch transistor Q 2 B, an eleventh switch transistor Q 3 B, a twelfth switch transistor Q 4 B, a thirteenth switch transistor Q 5 B, a fourteenth switch transistor Q 6 B, a fifteenth switch transistor Q 7 B, a sixteenth switch transistor Q 8 B, a fourth capacitor CF 1 B, a fifth capacitor CF 2 B and a sixth capacitor CF 3 B. All switch transistors in the first branch and the second branch are primary switch transistors, each of the primary switch transistors has a parasitic capacitor, for example, each of the first switch transistor Q 1 A, the second switch transistor Q 2 A, the third switch transistor Q 3 A, the fourth switch transistor Q 4 A, the fifth switch transistor Q 5 A, the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the eighth switch transistor Q 8 A, the ninth switch transistor Q 1 B, the tenth switch transistor Q 2 B, the eleventh switch transistor Q 3 B, the twelfth switch transistor Q 4 B, the thirteenth switch transistor Q 5 B, the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B and the sixteenth switch transistor Q 8 B has a parasitic capacitor. 
     An VIN presents an input voltage, the VIN is connected to GND via a capacitor CIN, the VIN is connected to a node C 1 PA via the first switch transistor Q 1 A, the node C 1 PA is connected to a node C 2 PA via the second switch transistor Q 2 A, the node C 1 PA is connected to a first connection node C 1 NA via the first capacitor CF 1 A, the node C 2 PA is connected to a node C 3 PA via the third switch transistor Q 3 A, the node C 2 PA is connected to a second connection node C 2 NA via the second capacitor CF 2 A, a node C 3 PA is connected to an output voltage VOUT via the fourth switch transistor Q 4 A, the node C 3 PA is connected to the first connection node C 1 NA via the third capacitor CF 3 A, the fifth switch transistor Q 5 A is connected between the output voltage VOUT and the first connection node C 1 NA, the first connection node C 1 NA is connected to GND via the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A is connected between the output voltage VOUT and the second connection node C 2 NA, and the second connection node C 2 NA is connected to GND via the eighth switch transistor Q 8 A. 
     Similarly, the VIN is connected to a node C 1 PB via the ninth switch transistor Q 1 B, the node C 1 PB is connected to a node C 2 PB via the tenth switch transistor Q 2 B, the node C 1 PB is connected to a third connection node C 1 NB via the fourth capacitor CF 1 B, the node C 2 PB is connected to a node C 3 PB via the eleventh switch transistor Q 3 B, the node C 2 PB is connected to a fourth connection node C 2 NB via the fifth capacitor CF 2 B, the node C 3 PB is connected to the output voltage VOUT via the twelfth switch transistor Q 4 B, the node C 3 PB is connected to the third connection node C 1 NB via the sixth capacitor CF 3 B, the thirteenth switch transistor Q 5 B is connected between the output voltage VOUT and the third connection node C 1 NB, the third connection node C 1NB is connected to GND via the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B is connected between the output voltage VOUT and the fourth connection node C 2 NB, and the fourth connection node C 2 NB is connected to GND via the sixteenth switch transistor Q 8 B. 
     The output voltage VOUT is connected to GND via a capacitor COUT, and there is a load resistance ROUT between VOUT and GND. 
     The inductive branch is connected between the first branch and the second branch of the Dickson 4:1 switched capacitor voltage converter, and the inductive branch includes a seventeenth switch transistor QX 1 A, an eighteenth switch transistor QX 2 A, a nineteenth switch transistor QX 3 A, a twentieth switch transistor QX 1 B, a twenty-first switch transistor QX 2 B, a twenty-second switch transistor QX 3 B and an inductor L 0 . The second connection node C 2 NA is connected to a node LXA via the seventeenth switch transistor QX 1 A, a third connection node C 1 NB is connected to the node LXA via the nineteenth switch transistor QX 3 A, the node LXA is connected to GND via the eighteenth switch transistor QX 2 A, the fourth connection node C 2 NB is connected to a node LXB via the twentieth switch transistor QX 1 B, the first connection node C 1 NA is connected to the node LXB via the twenty-second switch transistor QX 3 B, the node LXB is connected to GND via the twenty-first switch transistor QX 2 B, and the node LXA and the node LXB are connected via the inductor L 0 . 
       FIG.  3    shows a working sequence of a two-branch Dickson 4:1 switched voltage converter of an embodiment of the present application, there are four working states of phase 1 (T 4 -T 1 ), phase 2 (T 1 -T 2 ), phase 3 (T 2 -T 3 ) and phase 4 (T 3 -T 4 ) in sequence within one working cycle. 
     Voltage patterns corresponding to Q 1 A, Q 2 A, Q 3 A, Q 4 A, Q 5 A, Q 6 , Q 7 A and Q 8 A present on-off states of the first switch transistor Q 1 A, the second switch transistor Q 2 A, the third switch transistor Q 3 A, the fourth switch transistor Q 4 A, the fifth switch transistor Q 5 A, the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A and the eighth switch transistor Q 8 A respectively. Voltage patterns corresponding to Q 1 B, Q 2 B, Q 3 B, Q 4 B, Q 5 B, Q 6 B, Q 7 B and Q 8 B present on-off states of the ninth switch transistor Q 1 B, the tenth switch transistor Q 2 B, the eleventh switch transistor Q 3 B, the twelfth switch transistor Q 4 B, the thirteenth switch transistor Q 5 B, the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B and the sixteenth switch transistor Q 8 B respectively. Voltage patterns corresponding to QX 1 A, QX 2 A, QX 3 A, QX 1 B, QX 2 B and QX 3 B present on-off states of the seventeenth switch transistor QX 1 A, the eighteenth switch transistor QX 2 A, the nineteenth switch transistor QX 3 A, the twentieth switch transistor QX 1 B, the twenty-first switch transistor QX 2 B and the twenty-second switch transistor QX 3 B respectively. Voltage patterns corresponding to C 1 NA and C 2 NB are voltage waveforms of the first connection node C 1 NA and the fourth connection node C 2 NB respectively, voltage patterns corresponding to C 2 NA and C 1 NB are voltage waveforms of the second connection node C 2 NA and the third connection node C 1 NB respectively, voltage patterns corresponding to LXA and LXB are voltage waveforms of nodes LXA and LXB respectively, and current pattern corresponding to I_L0 is a current waveform of the inductor L 0 . 
       FIG.  4    shows a working state of the Dickson switched capacitor converter in the phase 1 (T 0 -T 1 ). The first switch transistor Q 1 A, the third switch transistor Q 3 A, the fifth switch transistor Q 5 A and the eighth switch transistor Q 8 A are turned on, the second switch transistor Q 2 A, the fourth switch transistor Q 4 A, the sixth switch transistor Q 6 A and the seventh switch transistor Q 7 A are turned off, and the input voltage VIN is connected to the output voltage VOUT via the first capacitor CF 1 A, and the third capacitor CF 3 A is connected in series to the output voltage VOUT and then connected in parallel to the second capacitor CF 2 A; the ninth switch transistor Q 1 B, the eleventh switch transistor Q 3 B, the thirteenth switch transistor Q 5 B and the sixteenth switch transistor Q 8 B are turned off, the tenth switch transistor Q 2 B, the twelfth switch transistor Q 4 B, the fourteenth switch transistor Q 6 B and the fifteenth switch transistor Q 7 B are turned on, the sixth capacitor CF 3 B is connected in parallel to the output voltage VOUT, and the fifth capacitor CF 2 B is connected in series to the output voltage VOUT and then connected in parallel to the fourth capacitor CF 1 B. The seventeenth switch transistor QX 1 A, the nineteenth switch transistor QX 3 A and the twenty-first switch transistor QX 2 B are turned on, the twentieth switch transistor QX 1 B, the twenty-second switch transistor QX 3 B and the eighteenth switch transistor QX 2 A are turned off, and the second connection node C 2 NA is connected GND via the seventeenth switch transistor QX 1 A, the inductor L 0  and the twenty-first switch transistor QX 2 B respectively, the third connection node C 1 NB is connected to GND via the nineteenth switch transistor QX 3 A, the inductor L 0  and the twenty-first switch transistor QX 2 B respectively. When phase 4 ends and the phase 1 starts, a voltage of the second connection node C 2 NA is zero, a voltage of the first connection node C 1 NA is the output voltage VOUT, a voltage of the node C 2 PA and a voltage of the node C 3 PA are twice the output voltage: 2*VOUT, a voltage of the node C 1 PA is the input voltage VIN, a voltage difference between both terminals of each of the eighth switch transistor Q 8 A, the fifth switch transistor Q 5 A, the third switch transistor Q 3 A and the first switch transistor Q 1 A is zero before the eighth switch transistor Q 8 A, the fifth switch transistor Q 5 A, the third switch transistor Q 3 A and the first switch transistor Q 1 A are turned on respectively, and the respective voltage differences of the eighth switch transistor Q 8 A, the fifth switch transistor Q 5 A, the third switch transistor Q 3 A and the first switch transistor Q 1 A do not change before and after being switched on and off; a voltage of the fourth connection node C 2 NB is the output voltage VOUT, a voltage of the third connection node C 1 NB is zero, a voltage of the node C 3 PB is the output voltage VOUT, a voltage of the node C 1 PB and a voltage of the node C 2 PB are three times the output voltage: 3*VOUT, a voltage difference between both terminals of each of the fifteenth switch transistor Q 7 B, the fourteenth switch transistor Q 6 B, the twelfth switch transistor Q 4 B and the tenth switch transistor Q 2 B is zero before the fifteenth switch transistor Q 7 B, the fourteenth switch transistor Q 6 B, the twelfth switch transistor Q 4 B and the tenth switch transistor Q 2 B are turned on respectively, and the respective voltage differences of the fifteenth switch transistor Q 7 B, the fourteenth switch transistor Q 6 B, the twelfth switch transistor Q 4 B and the tenth switch transistor Q 2 B do not change before and after being switched on and off. In the phase 1, a voltage of the first connection node C 1 NA and a voltage of the fourth connection node C 2 NB are equal to the output voltage VOUT, a voltage of the second connection node C 2 NA and a voltage of the third connection node C 1 NB are equal to zero, a voltage of the node LXA and a voltage of the node LXB are equal to zero, and the current of the inductor L 0  is zero. 
       FIG.  5    shows a working state of the Dickson switched capacitor converter in the phase 2 (T 1 -T 2 ). The first switch transistor Q 1 A, the second switch transistor Q 2 A, the third switch transistor Q 3 A, the fourth switch transistor Q 4 A, the fifth switch transistor Q 5 A, the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the eighth switch transistor Q 8 A, the ninth switch transistor Q 1 B, the tenth switch transistor Q 2 B, the eleventh switch transistor Q 3 B, the twelfth switch transistor Q 4 B, the thirteenth switch transistor Q 5 B, the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B and the sixteenth switch transistor Q 8 B are turned off, the eighteenth switch transistor QX 2 A and the twenty-first switch transistor QX 2 B are turned off, the seventeenth switch transistor QX 1 A, the nineteenth switch transistor QX 3 A, the twentieth switch transistor QX 1 B and the twenty-second switch transistor QX 3 B are turned on. The second connection node C 2 NA and the third connection node C 1 NB are connected a first terminal of the inductor L 0  via the seventeenth switch transistor QX 1 A and the nineteenth switch transistor QX 3 A respectively, the fourth connection node C 2 NB and the first connection node C 1 NA are connected via a second terminal of the inductor L 0  via the twentieth switch transistor QX 1 B and the twenty-second switch transistor QX 3 B respectively. At the beginning of the phase 2, a voltage of the fourth connection node C 2 NB and a voltage of the first connection node C 1 NA are equal to the output voltage VOUT, and a voltage of the second connection node C 2 NA and a voltage of the third connection node C 1 NB are equal to zero. When the fourth connection node C 2 NB with a high-voltage and the first connection node C 1 NA with the high-voltage are connected to the second connection node C 2 NA with a zero-voltage and the third connection node C 1 NB with the zero-voltage via the inductor L 0 , the current of the inductor L 0  flows from the LXB to the LXA and starts to increase, a voltage of the fourth connection node C 2 NB and a voltage of the first connection node C 1 NA decrease, and a voltage of the second connection node C 2 NA and a voltage of the third connection node C 1 NB increase; and when the voltage of the fourth connection node C 2 NB, the voltage of the first connection node C 1 NA, the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB are equal, the current of the inductor L 0  reaches a maximum value and then starts to decrease . When the current of the inductor L 0  decreases to zero, the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA decrease to zero, and the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB increase to the output voltage VOUT; and meanwhile, the voltage of the node C 2 PB decreases to 2*VOUT, the voltage of the node C 1 PA decreases to 3*VOUT, the voltage of the node C 3 PA decreases to VOUT, the voltage of the node C 2 PA increases to 3*VOUT, the voltage of the node C 1 PB increases to the input voltage VIN, and the voltage of the node C 3 PB increases to 2*VOUT, at this time, the controller controls the switches to end the phase 2 state and start the phase 3. 
       FIG.  6    shows a operation of the Dickson switched-capacitor converter in phase 3 (T 2 -T 3 ). The first switch transistor Q 1 A, the third switch transistor Q 3 A, the fifth switch transistor Q 5 A and the eighth switch transistor Q 8 A are turned off, the second switch transistor Q 2 A, the fourth switch transistor Q 4 A, the sixth switch transistor Q 6 A and the seventh switch transistor Q 7 A are turned on, the third capacitor CF 3 A is connected in parallel to the output voltage VOUT, and the second capacitor CF 2 A is connected in series to the output voltage VOUT and then connected in parallel to the first capacitor CF 1 A. The ninth switch transistor Q 1 B, the eleventh switch transistor Q 3 B, the thirteenth switch transistor Q 5 B and the sixteenth switch transistor Q 8 B are turned on, the tenth switch transistor Q 2 B, the twelfth switch transistor Q 4 B, the fourteenth switch transistor Q 6 B and the fifteenth switch transistor Q 7 B are turned off, the input voltage VIN is connected to the output voltage VOUT via the fourth capacitor CF 1B, and the sixth capacitor CF 3 B is connected in series to the output voltage VOUT and then connected in parallel to the fifth capacitor CF 2 B. The seventeenth switch transistor QX 1 A, the nineteenth switch transistor QX 3 A and the twenty-first switch transistor QX 2 B are turned off, the twentieth switch transistor QX 1 B, the twenty-second switch transistor QX 3 B and the eighteenth switch transistor QX 2 A are turned on, and the fourth connection node C 2 NB is connected to GND via the twentieth switch transistor QX 1 B, the inductor L 0  and the eighteenth switch transistor QX 2 A respectively, and the first connection node C 1 NA is connected to GND via the twenty-second switch transistor QX 3 B, the inductor L 0  and the eighteenth switch transistor QX 2 A respectively. When the phase 2 ends and the phase 3 starts, the voltage of the first connection node C 1 NA is zero, a voltage of the second connection node C 2 NA is the output voltage VOUT, a voltage of the node C 1 PA and a voltage of the node C 2 PA are three times the output voltage: 3*VOUT, a voltage of the node C 3 PA is the output voltage VOUT, a voltage difference between both terminals of each the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the second switch transistor Q 2 A and the fourth switch transistor Q 4 A is zero before the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the second switch transistor Q 2 A and the fourth switch transistor Q 4 A are turned on respectively, and the respective voltage differences of the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the second switch transistor Q 2 A and the fourth switch transistor Q 4 A do not change before and after being switched on and off; the voltage of the third connection node C 1 NB is the output voltage VOUT, the voltage of the fourth connection node C 2 NB is zero, the voltage of the node C 2 PB and the voltage of the node C 3 PB are three times the output voltage: 3*VOUT, the voltage of the node C 1 PB is the input voltage VIN, a voltage difference between both terminals of each of the thirteenth switch transistor Q 5 B, the sixteenth switch transistor Q 8 B, the eleventh switch transistor Q 3 B and the ninth switch transistor Q 1 B is zero before the thirteenth switch transistor Q 5 B, the sixteenth switch transistor Q 8 B, the eleventh switch transistor Q 3 B and the ninth switch transistor Q 1 B are turned on respectively, and the respective voltage differences of the thirteenth switch transistor Q 5 B, the sixteenth switch transistor Q 8 B, the eleventh switch transistor Q 3 B and the ninth switch transistor Q 1 B do not change before and after being switched on and off. In the phase 3, the voltage of the third connection node C 1 NB and the voltage of the second connection node C 2 NA are equal to the output voltage VOUT, the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA are equal to zero, the voltage of the node LXA and the voltage of the node LXB are equal to zero, and the current of the inductor L 0  is zero. 
       FIG.  7    shows a working state of the Dickson switched capacitor converter in the phase 4 (T 3 -T 4 ). The first switch transistor Q 1 A, the second switch transistor Q 2 A, the third switch transistor Q 3 A, the fourth switch transistor Q 4 A, the fifth switch transistor Q 5 A, the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the eighth switch transistor Q 8 A, the ninth switch transistor Q 1 B, the tenth switch transistor Q 2 B, the eleventh switch transistor Q 3 B, the twelfth switch transistor Q 4 B, the thirteenth switch transistor Q 5 B, the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B and the sixteenth switch transistor Q 8 B are turned off, the eighteenth switch transistor QX 2 A and the twenty-first switch transistor QX 2 B are turned off, the seventeenth switch transistor QX 1 A, the nineteenth switch transistor QX 3 A, the twentieth switch transistor QX 1 B and the twenty-second switch transistor QX 3 B are turned on, the second connection node C 2 NA and the third connection node C 1 NB are connected a first terminal of the inductor L 0  via the seventeenth switch transistor QX 1 A and the nineteenth switch transistor QX 3 A respectively, the fourth connection node C 2 NB and the first connection node C 1 NA are connected via a second terminal of the inductor L 0  via the twentieth switch transistor QX 1 B and the twenty-second switch transistor QX 3 B respectively. At the beginning of the phase 4, a voltage of the second connection node C 2 NA and a voltage of the third connection node C 1 NB are equal to the output voltage VOUT, and a voltage of the fourth connection node C 2 NB and a voltage of the first connection node C 1 NA are equal to zero. When the second connection node C 2 NA with the high-voltage and the third connection node C 1 NB with the high-voltage are connected to the fourth connection node C 2 NB with the zero-voltage and the first connection node C 1 NA with the zero-voltage via the inductor L 0 , the current of the inductor L 0  flows from the node LXA to the node LXB and starts to increase, a voltage of the second connection node C 2 NA and a voltage of the third connection node C 1 NB decrease, and a voltage of the fourth connection node C 2 NB and a voltage of the first connection node C 1 NA increase, and when the voltage of the second connection node C 2 NA, the voltage of the third connection node C 1 NB, the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA are equal, the current of the inductor L 0  reaches the maximum value and then starts to decrease. When the current of the inductor L 0  decreases to zero, the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB decrease to zero, and the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA increase to the output voltage VOUT, and meanwhile, the voltage of the node C 2 PA decreases to 2*VOUT, the voltage of the node C 1 PB decreases to 3*VOUT, the voltage of the node C 3 PB decreases to VOUT, the voltage of the node C 2 PB increases to 3*VOUT, the voltage of the node C 1 PA increases to the input node voltage VIN, and the voltage of the node C 3 PA increases to 2*VOUT, at this time, the controller controls the switches to end the phase 4 and start the phase 1. 
     As described above, by controlling the seventeenth switch transistor QX 1 A, the eighteenth switch transistor QX 2 A, the nineteenth switch transistor QX 3 A, the twentieth switch transistor QX 1 B, the twenty-first switch transistor QX 2 B and the twenty-second switch transistor QX 3 B, when the Dickson switched capacitor voltage converter of the embodiments of the present application works in the phase 2, electric charges on the first connection node C 1 NA, the node C 1 PA, the node C 3 PA, the fourth connection node C 2 NB and the node C 2 PB can be completely transferred to the third connection node C 1 NB, the node C 1 PB, the node C 3 PB, the second connection node C 2 NA and the node C 2 PA via the inductor L 0 , so that, in the phase 3, a voltage difference between both terminals of each of the second switch transistor Q 2 A, the fourth switch transistor Q 4 A, the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the ninth switch transistor Q 1 B, the eleventh switch transistor Q 3 B, the thirteenth switch transistor Q 5 B and the sixteenth switch transistor Q 8 B is zero before the second switch transistor Q 2 A, the fourth switch transistor Q 4 A, the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the ninth switch transistor Q 1 B, the eleventh switch transistor Q 3 B, the thirteenth switch transistor Q 5 B and the sixteenth switch transistor Q 8 B are turned on respectively. In the phase 4, the electric charges on the third connection node C 1 NB, the node C 1 PB, the node C 3 PB, the second connection node C 2 NA and the node C 2 PA are completely transferred to the first connection node C 1 NA, the node C 1 PA, the node C 3 PA, the fourth connection node C 2 NB and the node C 2 PB via the inductor L 0 , so that, in the phase 1, a voltage difference between both terminals of each of the tenth switch transistor Q 2 B, the twelfth switch transistor Q 4 B, the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B, the first switch transistor Q 1 A, the third switch transistor Q 3 A, the fifth switch transistor Q 5 A and the eighth switch transistor Q 8 A is zero before the tenth switch transistor Q 2 B, the twelfth switch transistor Q 4 B, the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B, the first switch transistor Q 1 A, the third switch transistor Q 3 A, the fifth switch transistor Q 5 A and the eighth switch transistor Q 8 A are turned on respectively. In this way, a voltage difference between both terminals of each of the first switch transistor Q1A-the eighth switch transistor Q 8 A and the ninth switch transistor Q1B-the sixteenth switch transistor Q 8 B is zero each time before these switch transistors are turned on respectively, thereby greatly reducing the switching loss and improving the conversion efficiency of the Dickson switched capacitor voltage converter. 
     The Dickson switched capacitor voltage converter in  FIG.  2    can also work according to the working sequence as shown in  FIG.  8   , and there are four working states of phase 1 (T 0 -T 1 ), phase 2 (T 1 -T 2 ), phase 3 (T 2 -T 3 ) and phase 4 (T 3 -T 4 ) in sequence within one working cycle, and the main difference from  FIG.  3    is the control sequence of the seventeenth switch transistor QX 1 A, the twentieth switch transistor QX 1 B, the eighteenth switch transistor QX 2 A, the twenty-first switch transistor QX 2 B, the nineteenth switch transistor QX 3 A and the twenty-second switch transistor QX 3 B. This control method can also achieve the effect of decreasing the respective voltage differences between both terminals of the first switch transistor QIA-the eighth switch transistor Q 8 A and the ninth switch transistor Q1B-the sixteenth switch transistor Q 8 B to zero before these switch transistors are turned on. 
       FIG.  9    shows a working state of the Dickson switched capacitor converter in the phase 1 (T 0 -T 1 ). The first switch transistor Q 1 A, the third switch transistor Q 3 A, the fifth switch transistor Q 5 A and the eighth switch transistor Q 8 A are turned on, the second switch transistor Q 2 A, the fourth switch transistor Q 4 A, the sixth switch transistor Q 6 A and the seventh switch transistor Q 7 A are turned off, the input voltage VIN is connected to the output voltage VOUT via the first capacitor CF 1 A, and the third capacitor CF 3 A is connected in series to the output voltage VOUT and then connected in parallel to the second capacitor CF 2 A. The ninth switch transistor Q 1 B, the eleventh switch transistor Q 3 B, the thirteenth switch transistor Q 5 B and the sixteenth switch transistor Q 8 B are turned off, the tenth switch transistor Q 2 B, the twelfth switch transistor Q 4 B, the fourteenth switch transistor Q 6 B and the fifteenth switch transistor Q 7 B are turned on, the sixth capacitor CF 3 B is connected in parallel to the output voltage VOUT, and the fifth capacitor CF 2 B is connected in series to the output voltage VOUT and then connected in parallel to the fourth capacitor CF 1 B. The eighteenth switch transistor QX 2 A and the twenty-first switch transistor QX 2 B are turned on, the seventeenth switch transistor QX 1 A, the twentieth switch transistor QX 1 B, the nineteenth switch transistor QX 3 A and the twenty-second switch transistor QX 3 B are turned off, and the node LXA and the node LXB are connected to GND via the eighteenth switch transistor QX 2 A and the twenty-first switch transistor QX 2 B respectively. When the phase 4 ends and the phase 1 starts, a voltage of the second connection node C 2 NA is zero, a voltage of the first connection node C 1 NA is the output voltage VOUT, a voltage of the node C 2 PA and a voltage of the node C 3 PA are twice the output voltage 2*VOUT, a voltage of the node C 1 PA is the input voltage VIN, a voltage difference between both terminals of each of the eighth switch transistor Q 8 A, the fifth switch transistor Q 5 A, the third switch transistor Q 3 A and the first switch transistor Q 1 A is zero before the eighth switch transistor Q 8 A, the fifth switch transistor Q 5 A, the third switch transistor Q 3 A and the first switch transistor Q 1 A are turned on respectively, and the respective voltage differences of the eighth switch transistor Q 8 A, the fifth switch transistor Q 5 A, the third switch transistor Q 3 A and the first switch transistor Q 1 A do not change before and after being switched on and off. The voltage of the fourth connection node C 2 NB is the output voltage VOUT, the voltage of the third connection node C 1 NB is zero, the voltage of the node C 3 PB is the output voltage VOUT, the voltage of the node C 1 PB and the voltage of the node C 2 PB are three times the output voltage: 3*VOUT, a voltage difference between both terminals of each of the fifteenth switch transistor Q 7 B, the fourteenth switch transistor Q 6 B, the twelfth switch transistor Q 4 B and the tenth switch transistor Q 2 B is zero before the fifteenth switch transistor Q 7 B, the fourteenth switch transistor Q 6 B, the twelfth switch transistor Q 4 B and the tenth switch transistor Q 2 B are turned on respectively, and the respective voltage differences of the fifteenth switch transistor Q 7 B, the fourteenth switch transistor Q 6 B, the twelfth switch transistor Q 4 B and the tenth switch transistor Q 2 B do not change before and after being switched on and off. In the phase 1, the voltage of the first connection node C 1 NA and the voltage of the fourth connection node C 2 NB are equal to the output voltage VOUT, the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB are equal to zero, the voltage of the node LXA and the voltage of the node LXB are equal to zero, and the inductor L 0  current is zero. 
       FIG.  10    shows a working state of the Dickson switched capacitor converter in the phase 2 (T 1 -T 2 ). The first switch transistor Q 1 A, the second switch transistor Q 2 A, the third switch transistor Q 3 A, the fourth switch transistor Q 4 A, the fifth switch transistor Q 5 A, the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the eighth switch transistor Q 8 A, the ninth switch transistor Q 1 B, the tenth switch transistor Q 2 B, the eleventh switch transistor Q 3 B, the twelfth switch transistor Q 4 B, the thirteenth switch transistor Q 5 B, the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B and the sixteenth switch transistor Q 8 B are turned off, the eighteenth switch transistor QX 2 A and the twenty-first switch transistor QX 2 B are turned off, the seventeenth switch transistor QX 1 A, the nineteenth switch transistor QX 3 A, the twentieth switch transistor QX 1 B and the twenty-second switch transistor QX 3 B are turned on, and the second connection node C 2 NA and the third connection node C 1 NB are connected to a first terminal of the inductor L 0  via the seventeenth switch transistor QX 1 A and the nineteenth switch transistor QX 3 A respectively, and the fourth connection node C 2 NB and the first connection node C 1 NA are connected to a second terminal of the inductor L 0  via the twentieth switch transistor QX 1 B and the twenty-second switch transistor QX 3 B respectively. At the beginning of the phase 2, the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA are equal to the output voltage VOUT, and the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB are equal to zero. When the fourth connection node C 2 NB with the high-voltage and the first connection node C 1 NA with the high-voltage are connected to the second connection node C 2 NA with the zero-voltage and the third connection node C 1 NB with the zero-voltage via the inductor L 0 , the current of the inductor L 0  flows from the LXB to the LXA and starts to increase, the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA decrease, and the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB increase. When the voltage of the fourth connection node C 2 NB, the voltage of the first connection node C 1 NA, the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB are equal, the current of the inductor L 0  reaches the maximum value and then starts to decrease. When the current of the inductor L 0  decreases to zero, the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA decrease to zero, and the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB increase to the output voltage VOUT, and meanwhile, the voltage of the node C 2 PB decreases to 2*VOUT, the voltage of the node C 1 PA decreases to 3*VOUT, the voltage of the node C 3 PA decreases to VOUT, the voltage of the node C 2 PA increases to 3*VOUT, the voltage of the node C 1 PB increases to the input node voltage VIN, and the voltage of the node C 3 PB increases to 2*VOUT, at this time, the controller controls the switches to end the phase 2 and start the phase 3. 
       FIG.  11    shows a working state of the Dickson switched capacitor converter in the phase 3 (T 2 -T 3 ). The first switch transistor Q 1 A, the third switch transistor Q 3 A, the fifth switch transistor Q 5 A and the eighth switch transistor Q 8 A are turned off, the second switch transistor Q 2 A, the fourth switch transistor Q 4 A, the sixth switch transistor Q 6 A and the seventh switch transistor Q 7 A are turned on, the third capacitor CF 3 A is connected in parallel to the output voltage VOUT, and the second capacitor CF 2 A is connected in series to the output voltage VOUT and then connected in parallel to the first capacitor CF 1 A. The ninth switch transistor Q 1 B, the eleventh switch transistor Q 3 B, the thirteenth switch transistor Q 5 B and the sixteenth switch transistor Q 8 B are turned on, the tenth switch transistor Q 2 B, the twelfth switch transistor Q 4 B, the fourteenth switch transistor Q 6 B and the fifteenth switch transistor Q 7 B are turned off, the input voltage VIN is connected to the output voltage VOUT via the fourth capacitor CF 1 B, and the sixth capacitor CF 3 B is connected in series to the output voltage VOUT and then connected in parallel to the fifth capacitor CF 2 B. The seventeenth switch transistor QX 1 A, the nineteenth switch transistor QX 3 A, the twentieth switch transistor QX 1 B and the twenty-second switch transistor QX 3 B are turned off, the eighteenth switch transistor QX 2 A and the twenty-first switch transistor QX 2 B are turned on, the node LXA is connected to GND via the eighteenth switch transistor QX 2 A, and the node LXB is connected to GND via the twenty-first switch transistor QX 2 B. When the phase 2 ends and the phase 3 starts, the voltage of the first connection node C 1 NA is zero, the voltage of the second connection node C 2 NA is the output voltage VOUT, the voltage of the node C 1 PA and the voltage of the node C 2 PA are three times the output voltage: 3*VOUT, the voltage of the node C 3 PA is the output voltage VOUT, a voltage difference between both terminals of each of the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the second switch transistor Q 2 A and the fourth switch transistor Q 4 A is zero before the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the second switch transistor Q 2 A and the fourth switch transistor Q 4 A are turned on respectively, and the respective voltage differences of the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the second switch transistor Q 2 A and the fourth switch transistor Q 4 A do not change before and after being switched on and off. The voltage of the third connection node C 1 NB is the output voltage VOUT, the voltage of the fourth connection node C 2 NB is zero, the voltage of the node C 2 PB and the voltage of the node C 3 PB are three times the output voltage: 3*VOUT, the voltage of the node C 1 PB is the input voltage VIN, a voltage difference between both terminals of each of the thirteenth switch transistor Q 5 B, the sixteenth switch transistor Q 8 B, the eleventh switch transistor Q 3 B and the ninth switch transistor Q 1 B is zero before the thirteenth switch transistor Q 5 B, the sixteenth switch transistor Q 8 B, the eleventh switch transistor Q 3 B and the ninth switch transistor Q 1 B turned on respectively, and the respective voltage differences of the thirteenth switch transistor Q 5 B, the sixteenth switch transistor Q 8 B, the eleventh switch transistor Q 3 B and the ninth switch transistor Q 1 B do not change before and after being switched on and off. In the phase 3, the voltage of the third connection node C 1 NB and the voltage of the second connection node C 2 NA are equal to the output voltage VOUT, the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA are equal to zero, the voltage of the node LXA and the voltage of the node LXB are equal to zero, and the current of the inductor L 0  is zero. 
       FIG.  12    shows a working state of the Dickson switched capacitor converter in the phase 4 (T 3 -T 4 ). The first switch transistor Q 1 A, the second switch transistor Q 2 A, the third switch transistor Q 3 A, the fourth switch transistor Q 4 A, the fifth switch transistor Q 5 A, the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the eighth switch transistor Q 8 A, the ninth switch transistor Q 1 B, the tenth switch transistor Q 2 B, the eleventh switch transistor Q 3 B, the twelfth switch transistor Q 4 B, the thirteenth switch transistor Q 5 B, the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B and the sixteenth switch transistor Q 8 B are turned off, the eighteenth switch transistor QX 2 A and the twenty-first switch transistor QX 2 B are turned off, the seventeenth switch transistor QX 1 A, the nineteenth switch transistor QX 3 A, the twentieth switch transistor QX 1 B and the twenty-second switch transistor QX 3 B are turned on, the second connection node C 2 NA and the third connection node C 1 NB are connected to a first terminal of the inductor L 0  via the seventeenth switch transistor QX 1 A and the nineteenth switch transistor QX 3 A respectively, and the fourth connection node C 2 NB and the first connection node C 1 NA are connected to a second terminal of the inductor L 0  via the twentieth switch transistor QX 1 B and the twenty-second switch transistor QX 3 B respectively. At the beginning of the phase 4, the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB are equal to the output voltage VOUT, and the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA are equal to zero, and when the second connection node C 2 NA with the high-voltage and the third connection node C 1 NB with the high-voltage are connected to the fourth connection node C 2 NB with the zero-voltage and the first connection node C 1 NA with the zero-voltage via the inductor L 0 , the current of the inductor L 0  flows from the node LXA to the node LXB and starts to increase, the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB decrease, and the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA increase, when the voltage of the second connection node C 2 NA, the voltage of the third connection node C 1 NB, the voltage of the nodes the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA are equal, the current of the inductor L 0  reaches the maximum value and then starts to decrease. When the current of the inductor L 0  decrease s to zero, the voltage of the second connection node C 2 NA and the voltage of the third connection node C 1 NB decrease to zero, the voltage of the fourth connection node C 2 NB and the voltage of the first connection node C 1 NA increase to the output voltage VOUT; and meanwhile, the voltage of the node C 2 PA decreases to 2*VOUT, the voltage of the node C 1 PB decreases to 3*VOUT, the voltage of the node C 3 PB decreases to VOUT, the voltage of the node C 2 PB increases to 3*VOUT, the voltage of the node C 1 PA increases to the input node voltage VIN , and the voltage of the node C 3 PA increases to 2*VOUT, at this time, the controller controls the switches to end the phase 4 and start the phase 1. 
     According to the Dickson switched capacitor voltage converter of embodiments of the present application, by controlling the seventeenth switch transistor QX 1 A, the eighteenth switch transistor QX 2 A, the nineteenth switch transistor QX 3 A, the twentieth switch transistor QX 1 B, the twenty-first switch transistor QX 2 B and the twenty-second switch transistor QX 3 B according to above-mentioned two control sequences, the electric charges on the first connection node C 1 NA, the node C 1 PA, the node C 3 PA, the fourth connection node C 2 NB and the node C 2 PB are completely transferred to the third connection node C 1 NB, the node C 1 PB, the node C 3 PB, the second connection node C 2 NA and the node C 2 PA via the inductor L 0  in the phase 2, so that, in the phase 3, the voltage difference between both terminals of each of the second switch transistor Q 2 A, the fourth switch transistor Q 4 A, the sixth switch transistor Q 6 A, the seventh switch transistor Q 7 A, the ninth switch transistor Q 1 B, the eleventh switch transistor Q 3 B, the thirteenth switch transistor Q 5 B and the sixteenth switch transistor Q 8 B is zero before these switch transistors are turned on respectively. In the phase 4, the electric charges on the third connection node C 1 NB, the node C 1 PB, the node C 3 PB, the second connection node C 2 NA and the node C 2 PA are completely transferred to the first connection node C 1 NA, the node C 1 PA, the node C 3 PA, the fourth connection node C 2 NB and the node C 2 PB via the inductor L 0 , so that, in the phase 1, the voltage difference between both terminals of each of the tenth switch transistor Q 2 B, the twelfth switch transistor Q 4 B, the fourteenth switch transistor Q 6 B, the fifteenth switch transistor Q 7 B, the first switch transistor Q 1 A, the third switch transistor Q 3 A, the fifth switch transistor Q 5 A and the eighth switch transistor Q 8 A is zero before these switch transistors are turned on respectively. In this way, the voltage difference between both terminals of each of the first switch transistor QIA-the eighth switch transistor Q 8 A and the ninth switch transistor Q1B-the sixteenth switch transistor Q 8 B is zero before these switch transistor are turned on respectively, thereby greatly reducing the switching loss and improving the conversion efficiency of the Dickson switched capacitor voltage converter. 
     The Dickson switched capacitor voltage converter and control method of the embodiments of the present application are applicable not only to the two-branch Dickson 4:1 switched capacitor voltage converter of the above embodiments, but also to other Dickson switched capacitor voltage converters, such as the Dickson 5:1 switched capacitor voltage converter as shown in  FIG.  13   . 
       FIG.  13    is a schematic diagram of a circuit structure of a Dickson 5:1 switched capacitor voltage converter of an embodiment of the present application, the Dickson 5:1 switched capacitor voltage converter includes an inductive branch, a first branch and a second branch. 
     The first branch includes a first switch transistor Q 1 A, a second switch transistor Q 2 A, a third switch transistor Q 3 A, a fourth switch transistor Q 4 A, a fifth switch transistor Q 5 A, a sixth switch transistor Q 6 A, a seventh switch transistor Q 7 A, an eighth switch transistor Q 8 A, a first sub-switch transistor Q 9 A, a first capacitor CF 1 A, a second capacitor CF 2 A, a third capacitor CF 3 A and a first sub-capacitor CF 4 A; the second branch includes a ninth switch transistor Q 1 B, a tenth switch transistor Q 2 B, an eleventh switch transistor Q 3 B, a twelfth switch transistor Q 4 B, a thirteenth switch transistor Q 5 B, a fourteenth switch transistor Q 6 B, a fifteenth switch transistor Q 7 B, a sixteenth switch transistor Q 8 B, a second sub-switch transistor Q 9 B, a fourth capacitor CF 1 B, a fifth capacitor CF 2 B, a sixth capacitor CF 3 B and a second sub-capacitor CF 4 B. All switch transistors and sub-switch transistors in the first branch and the second branch are primary switch transistors, each of the primary switch transistors has a parasitic capacitor. 
     A first terminal of the first switch transistor Q 1 A and a first terminal of the ninth switch transistor Q 1 B are connected an input terminal of the Dickson 5:1 switched capacitor voltage converter, and the input terminal is connected to an external input voltage. A second terminal of the first switch transistor Q 1 A is connected to a first terminal of the second switch transistor Q 2 A and a first terminal of the first capacitor CF 1 A, and a second terminal of the ninth switch transistor Q 1 B is connected to a first terminal of the tenth switch transistor Q 2 B and a first terminal of the fourth capacitor CF 1 B. A second terminal of the second switch transistor Q 2 A is connected to a first terminal of the third switch transistor Q 3 A and a first terminal of the second capacitor CF 2 A, and a second terminal of the tenth switch transistor Q 2 B is connected to a first terminal of the eleventh switch transistor Q 3 B and a first terminal of the fifth capacitor CF 2 B. A second terminal of the third switch transistor Q 3 A is connected to a first terminal of the fourth switch transistor Q 4 A and a first terminal of the third capacitor CF 3 A, and a second terminal of the eleventh switch transistor Q 3 B is connected to a first terminal of the twelfth switch transistor Q 4 B and a first terminal of the sixth capacitor CF 3 B. 
     A second terminal of the fourth switch transistor Q 4 A is connected to a first terminal of the fifth switch transistor Q 5 A and a first terminal of the first sub-capacitor CF 4 A, and a second terminal of the twelfth switch transistor Q 4 B is connected to a first terminal of the thirteenth switch transistor Q 5 B and a first terminal of the second sub-capacitor CF 4 B. A second terminal of the fifth switch transistor Q 5 A is connected to a first terminal of the sixth switch transistor Q 6 A and a first terminal of the eighth switch transistor Q 8 A, a second terminal of the sixth switch transistor Q 6 A is connected to a second terminal of the first sub-capacitor CF 4 A, a second terminal of the second capacitor CF 2 A and a first terminal of the seventh switch transistor Q 7 A, a second terminal of the eighth switch transistor Q 8 A is connected to a first terminal of the first sub-switch transistor Q 9 A, a second terminal of the first capacitor CF 1 A and a second terminal of the third capacitor CF 3 A, and a second terminal of the seventh switch transistor Q 7 A and a second terminal of the first sub-switch transistor Q 9 A are grounded. 
     A second terminal of the thirteenth switch transistor Q 5 B is connected to a first terminal of the fourteenth switch transistor Q 6 B and a first terminal of the sixteenth switch transistor Q 8 B, and a second terminal of the fourteenth switch transistor Q 6 B is connected to a second terminal of the second sub-capacitor CF 4 B, a second terminal of the fifth capacitor CF 2 B and a first terminal of the fifteenth switch transistor Q 7 B. A second terminal of the sixteenth switch transistor Q 8 B is connected to a first terminal of the second sub-switch transistor Q 9 B, a second terminal of the fourth capacitor CF 1 B and a second terminal of the sixth capacitor CF 3 B. A second terminal of the fifteenth switch transistor Q 7 B and a second terminal of the second sub-switch transistor Q 9 B are grounded. 
     The second terminal of the fifth switch transistor Q 5 A, the first terminal of the sixth switch transistor Q 6 A, the first terminal of the eighth switch transistor Q 8 A, the second terminal of the thirteenth switch transistor Q 5 B, the first terminal of the fourteenth switch transistor Q 6 B and the first terminal of the sixteenth switch transistor Q 8 B are connected to the output terminal of the Dickson 5:1 switched capacitor voltage converter. 
     The inductive branch includes a seventeenth switch transistor QX 1 A, an eighteenth switch transistor QX 2 A, a nineteenth switch transistor QX 3 A, a twentieth switch transistor QX 1 B, a twenty-first switch transistor QX 2 B, a twenty-second switch transistor QX 3 B and the inductor L 0 . 
     The second terminal of the first capacitor CFIA, the second terminal of the third capacitor CF 3 A, the second terminal of the eighth switch transistor Q 8 A and the first terminal of the first sub-switch transistor Q 9 A are connected to a first connection node C 1 NA; the second terminal of the second capacitor CF 2 A, the second terminal of the first sub-capacitor CF 4 A, the second terminal of the sixth switch transistor Q 6 A and the first terminal of the seventh switch transistor Q 7 A are connected to a second connection node C 2 NA; the second terminal of the fourth capacitor CF 1 B, the second terminal of the sixth capacitor CF 3 B, the second terminal of the sixteenth switch transistor Q 8 B and the first terminal of the second sub-switch transistor Q 9 B are connected to a third connection node C 1 NB; and the second terminal of the fifth capacitor CF 2 B, the second terminal of the second sub-capacitor CF 4 B, the second terminal of the fourteenth switch transistor Q 6 B and the first terminal of the fifteenth switch transistor Q 7 B are connected to a fourth connection node C 2 NB. 
     The first connection node C 1 NA is connected to the node LXA via the seventeenth switch transistor QX 1 A, the fourth connection node C 2 NB is connected to the node LXA via the nineteenth switch transistor QX 3 A, the node LXA is connected to the ground via the eighteenth switch transistor QX 2 A, the third connection node C 1 NB is connected the node LXB via the twentieth switch transistor QX 1 B, the second connection node C 2 NA is connected to the node LXB via the twenty-second switch transistor QX 3 B, the node LXB is connected the ground via the twenty-first switch transistor QX 2 B, and the node LXA and the node LXB are connected via the inductor L 0 . 
     In all embodiments of the present application, all switch transistors in the first branch and the second branch are primary switch transistors, each of the primary switch transistors has a parasitic capacitor. 
     The type and number of switch transistors are not limited to the six N-transistors in the above examples, but may be switch transistors or diodes of other number and other type. 
     In all embodiments of the present application, all switch transistors and sub- switch transistors in the first branch and the second branch are primary switch transistors, each of the primary switch transistors has a parasitic capacitor. 
     The control sequence is not limited to the above two control sequences, and other control sequences may be used to control the switch transistors to transfer the electric charges on one branch completely to another branch via the inductor within a short period of time when the primary switch transistors are turned off, so that the effect of zero voltage switching is also achieved, thereby improving the conversion efficiency of the Dickson switched capacitor voltage converter. 
     Since the specific implementation modes of the circuit structure are various, and the corresponding control methods are also various, they cannot be exemplified one by one in the present application, after those skilled in the art understand the contents of the present application, various modifications, variations or equivalents of the above described examples may be readily conceived, but still be controlled by the limitations set forth in the claims and any equivalents thereof.