A switched capacitor voltage converter

Abstract

The application relates to a switched capacitor voltage converter. The application adds inductors and a plurality of switching tubes between two branches of a traditional parallel switched capacitor converter structure. By controlling the on and off of the switching tubes, the charges on the parasitic capacitors of one branch are completely transferred to the other branch through the inductors within a period after the main switching tube is turned off. The voltage difference across the main switching tube becomes zero. Thus, the voltage difference across the main switching tube is zero at the moment when the main switching tube is turned on, thereby reducing the switching loss when the switching tube is switched and improving the conversion efficiency of the switched capacitor voltage converter.

Description

Technical Field

[0001] This application belongs to the field of switching power supply technology, specifically relating to a switched capacitor voltage converter. Background Technology

[0002] Switched capacitor voltage converters are widely used in various power management applications as a basic power conversion structure. They can convert an input DC voltage into another DC voltage output.

[0003] like Figure 1 The diagram shows a conventional dual-parallel 2:1 switched capacitor voltage converter. Branch A of this circuit transfers charge from the input to the output through the first switch Q1A to the fourth switch Q4A and the first capacitor CFA. Similarly, branch B transfers charge from the input to the output through the fifth switch Q1B to the eighth switch Q4B and the second capacitor CFB. Ultimately, the output voltage VOUT = VIN / 2 and the output current IOUT = 2*IIN are achieved.

[0004] Conversion efficiency is a crucial indicator of switched-capacitor voltage converters (SVCs), determining their load-carrying capacity and temperature rise. Higher conversion efficiency results in greater load-carrying capacity and lower temperature rise. The main losses in SVCs originate from: 1) conduction losses of the individual transistors in the circuit; 2) switching losses during transistor switching; and 3) drive losses of the individual transistors. Improving conversion efficiency hinges on minimizing these losses. Switching losses are directly proportional to the voltage difference across the transistors during switching; a larger voltage difference leads to greater losses. Therefore, current SVCs suffer from low conversion efficiency and high switching losses during transistor switching, limiting their overall conversion effectiveness. Summary of the Invention

[0005] This application addresses the aforementioned problems, particularly the switching losses, by proposing a switched capacitor voltage converter that reduces the voltage difference across each switching transistor to almost zero during switching, thereby reducing switching losses and improving conversion efficiency.

[0006] To address the aforementioned problems, this application adds an inductor and several switching transistors between the two branches of a traditional switched-capacitor converter structure. By controlling the on and off states of these switching transistors, for a period of time after the main switching transistor is turned off, the charge on the parasitic capacitance of one branch is completely transferred to the other branch through the inductor, and the voltage difference across the main switching transistor becomes zero. Thus, at the instant each main switching transistor is turned on, the voltage difference across each main switching transistor is zero, thereby reducing the switching losses during switching and improving the conversion efficiency of the switched-capacitor converter.

[0007] This application provides a switched capacitor voltage converter, which is a dual-branch parallel 2:1 switched capacitor voltage converter, including an inductor branch and two branches. The two branches include a first branch and a second branch. The input voltage is converted into a different output voltage after passing through the two branches. The inductor branch connects the first branch and the second branch. The switching transistors in the first branch and the second branch are the main switching transistors. The inductor branch is used to transfer the charge on the parasitic capacitance of one branch to the other branch after the main switching transistors are turned off, so that the voltage difference across the main switching transistors becomes zero, so that the voltage difference across the main switching transistors is zero at the moment of turning on each main switching transistor.

[0008] In some embodiments, the first branch includes a first switch, a second switch, a third switch, a fourth switch, and a first capacitor, and the second branch includes a fifth switch, a sixth switch, a seventh switch, an eighth switch, and a second capacitor.

[0009] The first terminals of the first and fifth switching transistors are both input terminals of the switched-capacitor voltage converter, connected to an external input voltage. The second terminal of the first switching transistor is connected to the first terminal of the second switching transistor and the first terminal of the first capacitor. The second terminal of the fifth switching transistor is connected to the first terminal of the sixth switching transistor and the first terminal of the second capacitor. The second terminal of the second switching transistor is connected to the first terminal of the third switching transistor, and the second terminal of the sixth switching transistor is connected to the first terminal of the seventh switching transistor. The second terminal of the third switching transistor is connected to the second terminal of the first capacitor and the first terminal of the fourth switching transistor, and the second terminal of the seventh switching transistor is connected to the second terminal of the second capacitor and the first terminal of the eighth switching transistor. The second terminals of the fourth and eighth switching transistors are grounded. The connection of the second terminals of the second, third, sixth, and seventh switching transistors forms the output terminal of the switched-capacitor voltage converter.

[0010] In some embodiments, the inductor branch includes a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, and an inductor; the connection point of the first capacitor, the third switch, and the fourth switch is the first connection point, the connection point of the second capacitor, the seventh switch, and the eighth switch is the second connection point, the first end of the ninth switch is connected to the first connection point, the second end of the ninth switch is connected to the first end of the tenth switch and the first end of the inductor, and the second end of the tenth switch is grounded; the second end of the inductor is connected to the first end of the eleventh switch and the first end of the twelfth switch, the second end of the eleventh switch is grounded, and the second end of the twelfth switch is connected to the second connection point.

[0011] In some embodiments, the inductor branch includes a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, and an inductor; the connection point of the first terminal of the first capacitor, the second terminal of the first switch, and the first terminal of the second switch is connected to the first terminal of the ninth switch, the second terminal of the ninth switch is connected to the first terminal of the tenth switch and the first terminal of the inductor, and the second terminal of the tenth switch is connected to the output terminal of the switched capacitor voltage converter; the connection point of the second terminal of the fifth switch, the first terminal of the sixth switch, and the first terminal of the second capacitor is connected to the second terminal of the twelfth switch, the first terminal of the twelfth switch is connected to the second terminal of the inductor and the first terminal of the eleventh switch, and the second terminal of the eleventh switch is connected to the output terminal of the switched capacitor voltage converter.

[0012] In some embodiments, the inductor branch includes a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, and an inductor; the connection point of the first terminal of the first capacitor, the second terminal of the first switch, and the first terminal of the second switch is connected to the first terminal of the ninth switch, the second terminal of the ninth switch is connected to the first terminal of the tenth switch and the first terminal of the inductor, and the second terminal of the tenth switch is connected to the input terminal of the switched capacitor voltage converter; the connection point of the second terminal of the fifth switch, the first terminal of the sixth switch, and the first terminal of the second capacitor is connected to the second terminal of the twelfth switch, the first terminal of the twelfth switch is connected to the second terminal of the inductor and the first terminal of the eleventh switch, and the second terminal of the eleventh switch is connected to the input terminal of the switched capacitor voltage converter.

[0013] In some embodiments, one duty cycle of the switched capacitor voltage converter includes four phases arranged in sequence.

[0014] Phase 1: The first, third, sixth, eighth, tenth, and twelfth switches are all turned on, while the other switches are turned off. The input voltage is connected to the output terminal through the first capacitor, and the second capacitor is connected between the output terminal and ground. The inductor current is 0.

[0015] Second phase: The ninth and twelfth switches are turned on, and the other switches are turned off. The first connection point is connected to the second connection point through the ninth switch, the inductor, and the twelfth switch. The inductor current first increases and then decreases until the inductor current drops to 0, and the second phase ends.

[0016] Third phase: The second, fourth, fifth, seventh, ninth, and eleventh switches are all turned on, while the other switches are turned off. The first capacitor is connected between the output terminal and ground. The input voltage is connected to the output terminal through the second capacitor. The first connection point is grounded through the ninth switch, the inductor, and the eleventh switch. The inductor current is 0.

[0017] Fourth phase: The ninth and twelfth switches are turned on, and the other switches are turned off. The first connection point is connected to the second connection point through the ninth switch, the inductor, and the twelfth switch. The inductor current first increases and then decreases until the inductor current drops to 0. The fourth phase ends and the first phase begins.

[0018] In some embodiments, one duty cycle of the switched capacitor voltage converter includes four phases arranged in sequence.

[0019] Phase 1: The first, third, sixth, eighth, tenth, and eleventh switches are all turned on, while the other switches are turned off. The input voltage is connected to the output terminal through the first capacitor, and the second capacitor is connected between the output terminal and ground. The inductor current is 0.

[0020] Second phase: The ninth and twelfth switches are turned on, and the other switches are turned off. The first connection point is connected to the second connection point through the ninth switch, the inductor, and the twelfth switch. The inductor current first increases and then decreases until the inductor current drops to 0, and the second phase ends.

[0021] Third phase: The second, fourth, fifth, seventh, tenth, and eleventh switches are all turned on, while the other switches are turned off. The first capacitor is connected between the output terminal and ground. The input voltage is connected to the output terminal through the second capacitor. The two ends of the inductor are grounded through the tenth and eleventh switches, respectively. The inductor current is 0.

[0022] Fourth phase: The ninth and twelfth switches are turned on, and the other switches are turned off. The first connection point is connected to the second connection point through the ninth switch, the inductor, and the twelfth switch. The inductor current first increases and then decreases until the inductor current drops to 0. The fourth phase ends and the first phase begins.

[0023] This application adds an inductor and several switching transistors between the two branches of a conventional switched capacitor converter, controls the conduction and turn-off of these switching transistors, and completely transfers the charge on the parasitic capacitance of one branch to the other branch through the inductor during the dead time when all the main switching transistors are off, thereby achieving zero-voltage switching of all main switching transistors. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0025] Figure 1This is a schematic diagram of the circuit structure of a traditional dual-channel parallel 2:1 switched capacitor voltage converter.

[0026] Figure 2 A schematic diagram of the circuit structure of the first dual-channel parallel 2:1 switched capacitor voltage converter provided in this application.

[0027] Figure 3 This is the first working timing diagram provided for this application.

[0028] Figure 4 for Figure 3 The diagram shows the working state of the first phase in the first working timing sequence.

[0029] Figure 5 for Figure 3 The diagram shows the working state of the second phase in the first working sequence.

[0030] Figure 6 for Figure 3 The diagram shows the working state of the third phase in the first working timing sequence.

[0031] Figure 7 for Figure 3 The diagram shows the working state of the fourth phase in the first working timing sequence.

[0032] Figure 8 This is a second working timing diagram provided for this application.

[0033] Figure 9 for Figure 8 The diagram shows the working state of the first phase in the second working timing sequence.

[0034] Figure 10 for Figure 8 The diagram shows the working state of the second phase in the second working sequence.

[0035] Figure 11 for Figure 8 The diagram shows the working state of the third phase in the second working timing sequence.

[0036] Figure 12 for Figure 8 The diagram shows the working state of the fourth phase in the second working timing sequence.

[0037] Figure 13 A schematic diagram of the circuit structure of the second type of dual-channel parallel 2:1 switched capacitor voltage converter provided in this application.

[0038] Figure 14 A schematic diagram of the circuit structure of the third type of dual-channel parallel 2:1 switched capacitor voltage converter provided in this application. Detailed Implementation

[0039] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, where there is no conflict, the embodiments and features described in the embodiments of this application can be combined with each other.

[0040] Figure 2 This is a schematic diagram of the circuit structure of a dual-branch parallel 2:1 switched capacitor voltage converter according to an embodiment of this application. The dual-branch parallel 2:1 switched capacitor voltage converter includes an inductor branch and two branches, which include a first branch and a second branch.

[0041] The first branch includes a first switch Q1A, a second switch Q2A, a third switch Q3A, a fourth switch Q4A, and a first capacitor CFA. The second branch includes a fifth switch Q1B, a sixth switch Q2B, a seventh switch Q3B, an eighth switch Q4B, and a second capacitor CFB. All switches in the first and second branches are main switches, and each main switch has parasitic capacitance. For example, the first switch Q1A, the second switch Q2A, the third switch Q3A, the fourth switch Q4A, the fifth switch Q1B, the sixth switch Q2B, the seventh switch Q3B, and the eighth switch Q4B all have parasitic capacitance.

[0042] The input voltage is VIN, which is grounded to GND through capacitor CIN. VIN is connected to node CFHA through the first switch Q1A. Node CFHA is connected to the output voltage VOUT through the second switch Q2A. Node CFHA is also connected to the first connection point CFLA through the first capacitor CFA. A third switch Q3A is connected between the output voltage VOUT and the first connection point CFLA. The first connection point CFLA is grounded to GND through the fourth switch Q4A.

[0043] Similarly, VIN is connected to node CFHB through the fifth switch Q1B, node CFHB is connected to the output voltage VOUT through the sixth switch Q2B, node CFHB is also connected to the second connection point CFLB through the second capacitor CFB, the seventh switch Q3B is connected between the output voltage VOUT and the second connection point CFLB, and the second connection point CFLB is grounded to GND through the eighth switch Q4B.

[0044] For example, the first terminal of the first switch Q1A and the first terminal of the fifth switch Q1B are both input terminals of the switched capacitor voltage converter, and the input terminals are connected to the external input voltage. The second terminal of the first switch Q1A is connected to the first terminal of the second switch Q2A and the first terminal of the first capacitor CFA. The second terminal of the fifth switch Q1B is connected to the first terminal of the sixth switch Q2B and the first terminal of the second capacitor CFB.

[0045] The second terminal of the second switch Q2A is connected to the first terminal of the third switch Q3A, and the second terminal of the sixth switch Q2B is connected to the first terminal of the seventh switch Q3B.

[0046] The second terminal of the third switch Q3A is connected to the second terminal of the first capacitor CFA and the first terminal of the fourth switch Q4A. The second terminal of the seventh switch Q3B is connected to the second terminal of the second capacitor CFB and the first terminal of the eighth switch Q4B.

[0047] The second terminal of the fourth switch Q4A and the second terminal of the eighth switch Q4B are grounded.

[0048] The second terminal of the second switch Q2A, the first terminal of the third switch Q3A, the second terminal of the sixth switch Q2B, and the first terminal of the seventh switch Q3B are connected to form the output terminal of the switched capacitor voltage converter.

[0049] The output voltage VOUT is connected to the first terminal of capacitor COUT, the second terminal of capacitor COUT is grounded, and a load resistor ROUT is connected between VOUT and GND.

[0050] The inductor branch is connected between the two branches of the dual-branch parallel 2:1 switched capacitor voltage converter. The inductor branch includes the ninth switch QX1A, the tenth switch QX2A, the eleventh switch QX2B, the twelfth switch QX1B, and the inductor L0.

[0051] The first connection point CFLA is connected to node LXA through the ninth switch QX1A, and node LXA is connected to GND through the tenth switch QX2A. The second connection point CFLB is connected to node LXB through the twelfth switch QX1B, and node LXB is connected to GND through the eleventh switch QX2B. Nodes LXA and LXB are connected through inductor L0.

[0052] Figure 3The operating timing diagram of the switching voltage converter in this embodiment of the application shows four operating states in sequence within one operating cycle: phase 1 (T0~T1), phase 2 (T1~T2), phase 3 (T2~T3), and phase 4 (T3~T4). The voltage diagrams corresponding to Q1A, Q3A, Q2B, and Q4B respectively represent the switching states of the first switch Q1A, the third switch Q3A, the sixth switch Q2B, and the eighth switch Q4B. The voltage diagrams corresponding to Q2A, Q4A, Q1B, and Q3B respectively represent the switching states of the second switch Q2A, the fourth switch Q4A, the fifth switch Q4B, and the sixth switch Q4B. The switching states of transistors Q1B and the seventh switch Q3B are represented by voltage diagrams corresponding to QX2A, QX1A, QX2B, and QX1B, respectively. The voltage diagrams corresponding to CFLA and CFLB are the voltage waveforms at the first connection point CFLA and the second connection point CFLB, respectively. The voltage diagrams corresponding to LXA and LXB are the voltage waveforms at nodes LXA and LXB, respectively. The current diagram corresponding to I_L0 is the current waveform of inductor L0.

[0053] Figure 4The diagram shows the operating state of the switched-capacitor converter in phase 1 (T0~T1) according to an embodiment of this application. The first switch Q1A and the third switch Q3A are turned on, while the second switch Q2A and the fourth switch Q4A are turned off. The input voltage VIN is connected through the first capacitor CFA and the output capacitor COUT. The fifth switch Q1B and the seventh switch Q3B are turned off, while the sixth switch Q2B and the eighth switch Q4B are turned on. The second capacitor CFB and the output capacitor COUT are connected in parallel. The tenth switch QX2A and the twelfth switch QX1B are turned on, while the ninth switch QX1A and the eleventh switch QX2B are turned off. The second connection point CFLB is connected to GND through the twelfth switch QX1B, the inductor L0, and the tenth switch QX2A. At the start of phase 1, the voltage at the first connection point CFLA is the output voltage VOUT, and the voltage at node CFHA is the input voltage VIN. Before the third switch Q3A and the first switch Q1A are turned on, the voltage difference between the third switch Q3A and the first switch Q1A is zero, and the voltage difference between the third switch Q3A and the first switch Q1A remains unchanged before and after they are turned on. The voltage at the second connection point CFLB is zero, and the voltage at node CFHB is the output voltage VOUT. Before the eighth switch Q4B and the sixth switch Q2B are turned on, the voltage difference between the eighth switch Q4B and the sixth switch Q2B is zero, and the voltage difference between the eighth switch Q4B and the sixth switch Q2B remains unchanged before and after they are turned on. In phase 1, the voltage at the first connection point CFLA is equal to the output voltage VOUT, the voltage at the second connection point CFLB is zero, the voltages at nodes LXA and LXB are both zero, and the current in inductor L0 is zero.

[0054] Figure 5The diagram shows the operating state of the switched capacitor converter in phase 2 (T1~T2) according to an embodiment of this application. The first switch Q1A, second switch Q2A, third switch Q3A, fourth switch Q4A, fifth switch Q1B, sixth switch Q2B, seventh switch Q3B, eighth switch Q4B, tenth switch QX2A, and eleventh switch QX2B are all off. The ninth switch QX1A and twelfth switch QX1B are on. The first connection point CFLA is connected to the second connection point CFLB through the ninth switch QX1A, inductor L0, and twelfth switch QX1B. At the start of Phase 2, the voltage at the first connection point CFLA equals the output voltage VOUT, and the voltage at the second connection point CFLB is zero. After the first connection point CFLA is connected to the second connection point CFLB through inductor L0, the current in inductor L0 flows from node LXA to node LXB, and the current in inductor L0 begins to increase. The voltage at the first connection point CFLA decreases, and the voltage at the second connection point CFLB increases. When the voltages at the first and second connection points CFLA and CFLB are equal, the current in inductor L0 reaches its maximum, and then begins to decrease. When the current in inductor L0 drops to zero, the voltage at the first connection point CFLA drops to zero, the voltage at node CFHA drops to the output voltage VOUT, the voltage at the second connection point CFLB rises to the output voltage VOUT, and the voltage at node CFHB rises to the input voltage VIN. At this point, the controller ends Phase 2 and begins Phase 3.

[0055] Figure 6The diagram shows the operating state of the switched-capacitor converter in phase 3 (T2~T3) according to an embodiment of this application. The first switch Q1A and the third switch Q3A are off, while the second switch Q2A and the fourth switch Q4A are on. The first capacitor CFA and the output capacitor COUT are connected in parallel. The fifth switch Q1B and the seventh switch Q3B are on, while the sixth switch Q2B and the eighth switch Q4B are off. The input voltage VIN is connected to the output capacitor COUT through the second capacitor CFB. The ninth switch QX1A and the eleventh switch QX2B are on, while the twelfth switch QX1B and the tenth switch QX2A are off. The first connection point CFLA is connected to GND through the ninth switch QX1A, the inductor L0, and the eleventh switch QX2B. At the start of phase 3, the voltage at the first connection point CFLA is zero, the voltage at node CFHA is the output voltage VOUT, and before the fourth switch Q4A and the second switch Q2A are turned on, the voltage difference across the fourth switch Q4A and the second switch Q2A are both zero. The voltage differences across the fourth switch Q4A and the second switch Q2A remain unchanged before and after they are turned on. The voltage at the second connection point CFLB is the output voltage VOUT, the voltage at node CFHB is the input voltage VIN, and before the seventh switch Q3B and the fifth switch Q1B are turned on, the voltage difference across the seventh switch Q3B and the fifth switch Q1B are both zero. The voltage differences across the seventh switch Q3B and the fifth switch Q1B remain unchanged before and after they are turned on. In phase 3, the voltage at the first connection point CFLA is zero, the voltage at the second connection point CFLB is equal to the output voltage VOUT, the voltages at nodes LXA and LXB are both zero, and the current in inductor L0 is zero.

[0056] Figure 7The diagram shows the operating state of the switched capacitor converter in phase 4 (T3~T4) according to an embodiment of this application. The first switch Q1A, second switch Q2A, third switch Q3A, fourth switch Q4A, fifth switch Q1B, sixth switch Q2B, seventh switch Q3B, eighth switch Q4B, tenth switch QX2A, and eleventh switch QX2B are all off. The ninth switch QX1A and twelfth switch QX1B are on. The first connection point CFLA is connected to the second connection point CFLB through the ninth switch QX1A, inductor L0, and twelfth switch QX1B. At the start of phase 4, the voltage at the first connection point CFLA is zero, and the voltage at the second connection point CFLB is equal to the output voltage VOUT. After the first connection point CFLA is connected to the second connection point CFLB through inductor L0, the current in inductor L0 flows from node LXB to node LXA, and the current in inductor L0 begins to increase. The voltage at the second connection point CFLB decreases, and the voltage at the first connection point CFLA increases. When the voltages at the first and second connection points CFLA and CFLB are equal, the current in inductor L0 reaches its maximum, and then begins to decrease. When the current in inductor L0 drops to zero, the voltage at the second connection point CFLB drops to zero, the voltage at node CFHB drops to the output voltage VOUT, the voltage at the first connection point CFLA rises to the output voltage VOUT, and the voltage at node CFHA rises to the input voltage VIN. At this point, the controller ends phase 4 and restarts phase 1.

[0057] As described above, the switched capacitor voltage converter of this application, by controlling the ninth switch QX1A, the tenth switch QX2A, the eleventh switch QX2B, and the twelfth switch QX1B, in the operating state of phase 2, transfers all the charge of the first connection point CFLA and node CFHA to the second connection point CFLB and node CFHB through the inductor L0, so that in the operating state of phase 3, before the second switch Q2A, the fourth switch Q4A, the fifth switch Q1B, and the seventh switch Q3B are turned on, the voltage difference across the second switch Q2A, the fourth switch Q4A, the fifth switch Q1B, and the seventh switch Q3B are all zero. In phase 4, the charge at the second connection point CFLB and node CFHB is transferred to the first connection point CFLA and node CFHA through inductor L0. This ensures that in phase 1, before the first switch Q1A, the third switch Q3A, the sixth switch Q2B, and the eighth switch Q4B are turned on, the voltage difference across the first switch Q1A, the third switch Q3A, the sixth switch Q2B, and the eighth switch Q4B are all zero. Before the first switch Q1A, second switch Q2A, third switch Q3A, fourth switch Q4A, fifth switch Q1B, sixth switch Q2B, seventh switch Q3B, and eighth switch Q4B are turned on, the voltage differences across the first switch Q1A, second switch Q2A, third switch Q3A, fourth switch Q4A, fifth switch Q1B, sixth switch Q2B, seventh switch Q3B, and eighth switch Q4B are all zero. This reduces the switching losses of the switches and improves the conversion efficiency of the switched capacitor voltage converter.

[0058] Figure 2 The switched capacitor voltage converter shown in the embodiment of this application can also be configured as follows: Figure 8 The working sequence shown has four working states in sequence within one working cycle: phase 1 (T0~T1), phase 2 (T1~T2), phase 3 (T2~T3), and phase 4 (T3~T4). Figure 3The main difference lies in the control timing of the ninth switch QX1A, the twelfth switch QX1B, the tenth switch QX2A, and the eleventh switch QX2B. This control method can also achieve the effect of reducing the voltage difference across the first switch Q1A, the second switch Q2A, the third switch Q3A, the fourth switch Q4A, the fifth switch Q1B, the sixth switch Q2B, the seventh switch Q3B, and the eighth switch Q4B to zero before the first switch Q1A, the second switch Q2A, the third switch Q3A, the fourth switch Q4A, the fifth switch Q1B, the sixth switch Q2B, the seventh switch Q3B, and the eighth switch Q4B are turned on.

[0059] Figure 9 The diagram shows the operating state of the switched-capacitor converter in phase 1 (T0~T1) according to an embodiment of this application. The first switch Q1A and the third switch Q3A are turned on, while the second switch Q2A and the fourth switch Q4A are turned off. The input voltage VIN is connected through the first capacitor CFA and the output capacitor COUT. The fifth switch Q1B and the seventh switch Q3B are turned off, while the sixth switch Q2B and the eighth switch Q4B are turned on. The second capacitor CFB and the output capacitor COUT are connected in parallel. The tenth switch QX2A and the eleventh switch QX2B are turned on, while the ninth switch QX1A and the twelfth switch QX1B are turned off. Node LXA is connected to GND through the tenth switch QX2A, and node LXB is connected to GND through the eleventh switch QX2B. At the start of phase 1, the voltage at the first connection point CFLA is the output voltage VOUT, and the voltage at node CFHA is the input voltage VIN. Before the third switch Q3A and the first switch Q1A are turned on, the voltage difference between the third switch Q3A and the first switch Q1A is zero, and the voltage difference between the third switch Q3A and the first switch Q1A remains unchanged before and after they are turned on. The voltage at the second connection point CFLB is zero, and the voltage at node CFHB is the output voltage VOUT. Before the eighth switch Q4B and the sixth switch Q2B are turned on, the voltage difference between the eighth switch Q4B and the sixth switch Q2B is zero, and the voltage difference between the eighth switch Q4B and the sixth switch Q2B remains unchanged before and after they are turned on. In phase 1, the voltage at the first connection point CFLA is equal to the output voltage VOUT, the voltage at the second connection point CFLB is zero, the voltages at nodes LXA and LXB are both zero, and the current in inductor L0 is zero.

[0060] Figure 10The diagram shows the operating state of the switched capacitor converter in phase 2 (T1~T2) according to an embodiment of this application. The first switch Q1A, second switch Q2A, third switch Q3A, fourth switch Q4A, fifth switch Q1B, sixth switch Q2B, seventh switch Q3B, eighth switch Q4B, tenth switch QX2A, and eleventh switch QX2B are all off. The ninth switch QX1A and twelfth switch QX1B are on. The first connection point CFLA is connected to the second connection point CFLB through the ninth switch QX1A, inductor L0, and twelfth switch QX1B. At the start of Phase 2, the voltage at the first connection point CFLA equals the output voltage VOUT, and the voltage at the second connection point CFLB is zero. After the first connection point CFLA is connected to the second connection point CFLB through inductor L0, the current in inductor L0 flows from node LXA to node LXB, and the current in inductor L0 begins to increase. The voltage at the first connection point CFLA decreases, and the voltage at the second connection point CFLB increases. When the voltages at the first and second connection points CFLA and CFLB are equal, the current in inductor L0 reaches its maximum, and then begins to decrease. When the current in inductor L0 drops to zero, the voltage at the first connection point CFLA drops to zero, the voltage at node CFHA drops to the output voltage VOUT, the voltage at the second connection point CFLB rises to the output voltage VOUT, and the voltage at node CFHB rises to the input voltage VIN. At this point, the controller ends Phase 2 and begins Phase 3.

[0061] Figure 11The diagram shows the operating state of the switched-capacitor converter in phase 3 (T2~T3) according to an embodiment of this application. The second switch Q2A and the fourth switch Q4A are turned on, while the first switch Q1A and the third switch Q3A are turned off. The first capacitor CFA and the output capacitor COUT are connected in parallel. The sixth switch Q2B and the eighth switch Q4B are turned off, while the fifth switch Q1B and the seventh switch Q3B are turned on. The input voltage VIN is connected to the output capacitor COUT through the second capacitor CFB. The tenth switch QX2A and the eleventh switch QX2B are turned on, while the ninth switch QX1A and the twelfth switch QX1B are turned off. Node LXA is connected to GND through the tenth switch QX2A, and node LXB is connected to GND through the eleventh switch QX2B. At the start of phase 3, the voltage at the first connection point CFLA is zero, and the voltage at node CFHA is the output voltage VOUT. Before the fourth switch Q4A and the first switch Q1A are turned on, the voltage difference across both switches is zero, and this difference remains unchanged before and after they are turned on. At the second connection point CFLB, the voltage is the output voltage VOUT, and the voltage at node CFHB is the input voltage VIN. Before the seventh switch Q3B and the fifth switch Q1B are turned on, the voltage difference across both switches is zero, and this difference remains unchanged before and after they are turned on. In phase 3, the voltage at the first connection point CFLA is zero, the voltage at the second connection point CFLB is equal to the output voltage VOUT, the voltages at nodes LXA and LXB are both zero, and the current in inductor L0 is zero.

[0062] Figure 12The diagram shows the operating state of the switched capacitor converter in phase 4 (T3~T4) according to an embodiment of this application. The first switch Q1A, second switch Q2A, third switch Q3A, fourth switch Q4A, fifth switch Q1B, sixth switch Q2B, seventh switch Q3B, eighth switch Q4B, tenth switch QX2A, and eleventh switch QX2B are all off. The ninth switch QX1A and twelfth switch QX1B are on. The first connection point CFLA is connected to the second connection point CFLB through the ninth switch QX1A, inductor L0, and twelfth switch QX1B. At the start of phase 4, the voltage at the first connection point CFLA is zero, and the voltage at the second connection point CFLB is equal to the output voltage VOUT. After the first connection point CFLA is connected to the second connection point CFLB through inductor L0, the current in inductor L0 flows from node LXB to node LXA, and the current in inductor L0 begins to increase. The voltage at the second connection point CFLB decreases, and the voltage at the first connection point CFLA increases. When the voltages at the first and second connection points CFLA and CFLB are equal, the current in inductor L0 reaches its maximum, and then begins to decrease. When the current in inductor L0 drops to zero, the voltage at the second connection point CFLB drops to zero, the voltage at node CFHB drops to the output voltage VOUT, the voltage at the first connection point CFLA rises to the output voltage VOUT, and the voltage at node CFHA rises to the input voltage VIN. At this point, the controller ends phase 4 and begins phase 1.

[0063] The switched capacitor voltage converter in this embodiment controls the ninth switch QX1A, the tenth switch QX2A, the twelfth switch QX1B, and the eleventh switch QX2B through the above two control timing sequences. In phase 2, the charge at the first connection point CFLA and node CFHA is completely transferred to the second connection point CFLB and node CFHB through inductor L0. In phase 4, the charge at the second connection point CFLB and node CFHB is completely transferred to the first connection point CFLA and node CFHA through inductor L0, thereby allowing the first switch Q1A, the second switch Q2A, and the eleventh switch QX2B to operate smoothly. Before the switching transistors Q3A, Q4A, Q1B, Q2B, Q3B, and Q4B are turned on, the voltage differences across the first switching transistor Q1A, the second switching transistor Q2A, the third switching transistor Q3A, the fourth switching transistor Q4A, the fifth switching transistor Q1B, the sixth switching transistor Q2B, the seventh switching transistor Q3B, and the eighth switching transistor Q4B are all zero. This reduces the switching losses of the switching transistors and improves the conversion efficiency of the switched capacitor voltage converter.

[0064] The structure and control method of the switched capacitor voltage converter in this application are not only applicable to the dual-branch parallel 2:1 switched capacitor voltage converter of the above example, but can also be applied to switched capacitor voltage converters with other structures.

[0065] Of course, the inductor current in this application can be implemented in various ways. The type and number of switching transistors used are not limited to the four N-type transistors in the example above; other types of transistors or diodes can also be used. The added inductor and switch are not limited to being connected between the first connection point CFLA and the second connection point CFLB; they can also be connected to, for example... Figure 13 and Figure 14 Between nodes CFHA and CFHB in the system.

[0066] like Figure 13 The diagram shown is a circuit structure schematic of another switched-capacitor voltage converter according to another embodiment of this application. The switched-capacitor voltage converter includes an inductor branch, a first branch, and a second branch. Figure 13 The circuit structures of the first and second branches of the switched capacitor voltage converter in the embodiment are respectively... Figure 2 The circuit structures of the first and second branches of the switched capacitor voltage converter in this embodiment are the same. Figure 13 The inductor branch of the switched capacitor voltage converter in this embodiment has the following circuit connection relationship.

[0067] The connection point CFHA between the first terminal of the first capacitor CFA, the second terminal of the first switching transistor Q1A, and the first terminal of the second switching transistor Q2A is connected to the first terminal of the ninth switching transistor QX1A. The second terminal of the ninth switching transistor QX1A is connected to the first terminal of the tenth switching transistor QX2A and the first terminal of the inductor L0. The second terminal of the tenth switching transistor QX2A is connected to the output terminal.

[0068] The connection point CFHB between the second terminal of the fifth switch Q1B, the first terminal of the sixth switch Q2B, and the first terminal of the second capacitor CFB is connected to the second terminal of the twelfth switch QX1B. The first terminal of the twelfth switch QX1B is connected to the second terminal of the inductor L0 and the first terminal of the eleventh switch QX2B. The second terminal of the eleventh switch QX2B is connected to the output terminal.

[0069] like Figure 14 The diagram shown is a circuit structure schematic of another switched-capacitor voltage converter according to another embodiment of this application. The switched-capacitor voltage converter includes an inductor branch, a first branch, and a second branch. Figure 14 The circuit structures of the first and second branches of the switched capacitor voltage converter in the embodiment are respectively... Figure 2 The circuit structures of the first and second branches of the switched capacitor voltage converter in this embodiment are the same. Figure 14 The inductor branch of the switched capacitor voltage converter in this embodiment has the following circuit connection relationship.

[0070] The connection point CFHA between the first terminal of the first capacitor CFA, the second terminal of the first switch Q1A, and the first terminal of the second switch Q2A is connected to the first terminal of the ninth switch QX1A. The second terminal of the ninth switch QX1A is connected to the first terminal of the tenth switch QX2A and the first terminal of the inductor L0. The second terminal of the tenth switch QX2A is connected to the input terminal.

[0071] The connection point CFHB between the second terminal of the fifth switch Q1B, the first terminal of the sixth switch Q2B, and the first terminal of the second capacitor CFB is connected to the second terminal of the twelfth switch QX1B. The first terminal of the twelfth switch QX1B is connected to the second terminal of the inductor L0 and the first terminal of the eleventh switch QX2B. The second terminal of the eleventh switch QX2B is connected to the input terminal.

[0072] In all embodiments of this application, the switching transistors on the first branch and the second branch are main switching transistors, and all main switching transistors have parasitic capacitance.

[0073] The control timing is not limited to the two timings mentioned above. Other control timings can also be used to control these switching transistors so that during the time period when the main switching transistor is off, the charge of one branch is completely transferred to the other branch through the inductor, achieving the same zero-voltage switching effect, thereby improving the conversion efficiency of the switched capacitor voltage converter.

[0074] Because the specific implementation of the circuit structure is diverse, the corresponding control methods are also diverse. This application cannot provide examples for each one. Therefore, after those skilled in the art understand the content of this application, they can easily conceive of various modifications, variations or equivalents of the above examples, but they should still be subject to the limitations set forth in the claims and any equivalents.

Claims

1. A switched capacitor voltage converter, characterized in that, The switched capacitor voltage converter is a dual-branch parallel 2:1 switched capacitor voltage converter, including an inductor branch and two branches. The two branches include a first branch and a second branch. The input voltage is converted into another voltage output after passing through the two branches. The inductor branch connects the first branch and the second branch. The switching transistors in the first branch and the second branch are the main switching transistors. The inductor branch is used to transfer the charge on the parasitic capacitance of one branch to another branch after all the main switching transistors are turned off, so that the voltage difference across the main switching transistors becomes zero, so that the voltage difference across each main switching transistor is zero at the moment when each main switching transistor is turned on. The first branch includes a first switch, a second switch, a third switch, a fourth switch, and a first capacitor; the second branch includes a fifth switch, a sixth switch, a seventh switch, an eighth switch, and a second capacitor. The first terminal of the first switch and the first terminal of the fifth switch are both input terminals of the switched capacitor voltage converter. The input terminals are connected to an external input voltage. The second terminal of the first switch is connected to the first terminal of the second switch and the first terminal of the first capacitor. The second terminal of the fifth switch is connected to the first terminal of the sixth switch and the first terminal of the second capacitor. The second terminal of the second switch is connected to the first terminal of the third switch, and the second terminal of the sixth switch is connected to the first terminal of the seventh switch. The second terminal of the third switch is connected to the second terminal of the first capacitor and the first terminal of the fourth switch, and the second terminal of the seventh switch is connected to the second terminal of the second capacitor and the first terminal of the eighth switch. The second terminal of the fourth switch and the second terminal of the eighth switch are grounded; The second terminal of the second switch, the first terminal of the third switch, the second terminal of the sixth switch, and the first terminal of the seventh switch are connected to form the output terminal of the switched capacitor voltage converter.

2. The switched capacitor voltage converter according to claim 1, characterized in that, The inductor branch includes a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, and an inductor; The connection point of the second terminal of the first capacitor, the second terminal of the third switch, and the first terminal of the fourth switch is the first connection point; the connection point of the second terminal of the second capacitor, the second terminal of the seventh switch, and the first terminal of the eighth switch is the second connection point; the first terminal of the ninth switch is connected to the first connection point; the second terminal of the ninth switch is connected to the first terminal of the tenth switch and the first terminal of the inductor; and the second terminal of the tenth switch is grounded. The second end of the inductor is connected to the first end of the eleventh switch and the first end of the twelfth switch. The second end of the eleventh switch is grounded, and the second end of the twelfth switch is connected to the second connection point.

3. The switched capacitor voltage converter according to claim 1, characterized in that, The inductor branch includes a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, and an inductor; The connection point of the first terminal of the first capacitor, the second terminal of the first switching transistor, and the first terminal of the second switching transistor is connected to the first terminal of the ninth switching transistor. The second terminal of the ninth switching transistor is connected to the first terminal of the tenth switching transistor and the first terminal of the inductor. The second terminal of the tenth switching transistor is connected to the output terminal of the switched capacitor voltage converter. The connection point of the second terminal of the fifth switch, the first terminal of the sixth switch, and the first terminal of the second capacitor is connected to the second terminal of the twelfth switch. The first terminal of the twelfth switch is connected to the second terminal of the inductor and the first terminal of the eleventh switch. The second terminal of the eleventh switch is connected to the output terminal of the switched capacitor voltage converter.

4. The switched capacitor voltage converter according to claim 1, characterized in that, The inductor branch includes a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, and an inductor; The connection point of the first terminal of the first capacitor, the second terminal of the first switching transistor, and the first terminal of the second switching transistor is connected to the first terminal of the ninth switching transistor. The second terminal of the ninth switching transistor is connected to the first terminal of the tenth switching transistor and the first terminal of the inductor. The second terminal of the tenth switching transistor is connected to the input terminal of the switched capacitor voltage converter. The connection point of the second terminal of the fifth switch, the first terminal of the sixth switch, and the first terminal of the second capacitor is connected to the second terminal of the twelfth switch. The first terminal of the twelfth switch is connected to the second terminal of the inductor and the first terminal of the eleventh switch. The second terminal of the eleventh switch is connected to the input terminal of the switched capacitor voltage converter.

5. The switched capacitor voltage converter according to claim 2, characterized in that, One operating cycle of the switched capacitor voltage converter includes four phases arranged in sequence, namely: First phase: The first, third, sixth, eighth, tenth, and twelfth switches are all turned on, and the other switches are turned off. The input voltage is connected to the output terminal through the first capacitor, and the second capacitor is connected between the output terminal and ground. The inductor current is 0. Second phase: The ninth and twelfth switches are turned on, and the other switches are turned off. The first connection point is connected to the second connection point through the ninth switch, the inductor, and the twelfth switch. The inductor current first increases and then decreases until the inductor current drops to 0, at which point the second phase ends. Third phase: The second, fourth, fifth, seventh, ninth, and eleventh switches are all turned on, while the other switches are turned off. The first capacitor is connected between the output terminal and ground. The input voltage is connected to the output terminal through the second capacitor. The first connection point is grounded through the ninth switch, the inductor, and the eleventh switch. The inductor current is 0. Fourth phase: The ninth and twelfth switches are turned on, and the other switches are turned off. The first connection point is connected to the second connection point through the ninth switch, the inductor, and the twelfth switch. The inductor current first increases and then decreases until the inductor current drops to 0. The fourth phase ends and the first phase begins.

6. The switched capacitor voltage converter according to claim 2, characterized in that, One operating cycle of the switched capacitor voltage converter includes four phases arranged in sequence, namely: First phase: The first, third, sixth, eighth, tenth, and eleventh switches are all turned on, and the other switches are turned off. The input voltage is connected to the output terminal through the first capacitor, and the second capacitor is connected between the output terminal and ground. The inductor current is 0. Second phase: The ninth and twelfth switches are turned on, and the other switches are turned off. The first connection point is connected to the second connection point through the ninth switch, the inductor, and the twelfth switch. The inductor current first increases and then decreases until the inductor current drops to 0, at which point the second phase ends. Third phase: The second, fourth, fifth, seventh, tenth, and eleventh switches are all turned on, and the other switches are turned off. The first capacitor is connected between the output terminal and ground. The input voltage is connected to the output terminal through the second capacitor. The two ends of the inductor are grounded through the tenth and eleventh switches, respectively. The inductor current is 0. Fourth phase: The ninth and twelfth switches are turned on, and the other switches are turned off. The first connection point is connected to the second connection point through the ninth switch, the inductor, and the twelfth switch. The inductor current first increases and then decreases until the inductor current drops to 0. The fourth phase ends and the first phase begins.

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