Switch-timing in a switched-capacitor power converter

Abstract

In a power converter, each gate-driving circuit uses charge from a selected pump capacitor operate a corresponding switch. The switches transitions between different states, each of which corresponds to a particular interconnection of pump capacitors. During clocked operations, the first switch closes, thereby establishing a connection with the first pump capacitor. Prior to the first switch closing, the second switch closes.

The invention claimed is: 
     
       1. An apparatus comprising a switched-capacitor power-converter, wherein said switched-capacitor power-converter comprises an input, an output, a first plurality of switches, a second plurality of switches, and gate-driving circuits, each of which corresponds to a switch from said first plurality of switches, wherein each gate-driving circuit uses charge from a selected pump capacitor from a plurality of pump capacitors to operate a corresponding one of said switches from said first plurality of switches, wherein said first plurality of switches comprises a first switch, wherein said second plurality of switches comprises a second switch, wherein, during clocked operation of said switched-capacitor power-converter, said first plurality of switches transitions between different states, each of which corresponds to a particular interconnection of said pump capacitors, said pump capacitors including a first pump capacitor, wherein, during clocked operations, said first switch closes, thereby establishing a connection with said first pump capacitor, wherein, prior to said first switch closing, said second switch closes, wherein as a result of closure of said second switch, said first pump capacitor is pre-charged by the time said first switch closes. 
     
     
       2. The apparatus of  claim 1 , wherein said second switch is connected such that, when said second switch closes, a voltage arises across said first pump capacitor. 
     
     
       3. The apparatus of  claim 1 , wherein said second switch connects to an anode of said first pump capacitor. 
     
     
       4. The apparatus of  claim 1 , wherein closing said second switch connects said first pump capacitor to a phase voltage. 
     
     
       5. The apparatus of  claim 4 , wherein said second switch and said first switch are synchronized in operation. 
     
     
       6. The apparatus of  claim 5 , wherein said first switch and said second switch close concurrently. 
     
     
       7. The apparatus of  claim 5 , wherein said second switch closes before said first switch closes. 
     
     
       8. The apparatus of  claim 7 , wherein there exists a fixed time interval between closing said second switch and closing said first switch. 
     
     
       9. The apparatus of  claim 1 , further comprising a pre-charging circuit configured to limit voltage across said switches from said first plurality of switches during power-up of said switched-capacitor power-converter. 
     
     
       10. The apparatus of  claim 1 , further comprising a phase generator comprising phase switches, wherein said second switch is one of said phase switches. 
     
     
       11. The apparatus of  claim 10 , wherein said phase generator is configured to provide first and second phase voltages, wherein said second switch provides said first phase voltage upon closure thereof, and wherein said phase generator further comprises a third switch that, when closed provides said second phase voltage, wherein said first plurality of switches comprises a first subset of switches and a second subset of switches, wherein switches in said first subset open and close together, wherein switches in said second subset open and close together at times that differ from times at which said switches in said first subset open and close together, wherein, said first switch is in said first subset, wherein said second switch is synchronized with switches in said first subset, and wherein said third switch is synchronized with switches in said third subset. 
     
     
       12. The apparatus of  claim 11 , wherein, as a result of being synchronized with switches in said first subset, said second switch closes prior to closure of all switches in said first subset, and wherein, as a result of being synchronized with switches in said second subset, said third switch closes prior to closure of all switches ins said first subset. 
     
     
       13. The apparatus of  claim 1 , further comprising a control block that comprises circuitry that is configured to provide a first plurality of drive signals and to provide a second plurality of drive signals, wherein each drive signal from said first plurality of drive signals is connected to a one of the gate-driving circuit circuits that drives a gate of a transistor from a first plurality of transistors, wherein each drive signal from said second plurality of drive signals is connected to a one of the gate-driving circuit circuits that drives a gate of a transistor from a second plurality of transistors, wherein said drive signals from said first plurality of drive signals cooperate to cause all transistors that are in said first plurality of transistors to close together following closure of said second switch, and wherein said drive signals from said second plurality of drive signals is configured to cause all transistors in said second plurality of transistors to close together following closure of a third switch from said second plurality of switches. 
     
     
       14. The apparatus of  claim 13 , wherein said circuitry comprises a level shifter that is configured to receive first and second voltages and to transform said first and second voltages into third and fourth voltages, wherein said level shifter is configured to present a voltage difference that is equal to a difference between said third and fourth voltage to a the gate terminal of a the transistor that is from said first plurality of transistors. 
     
     
       15. The apparatus of  claim 1 , further comprising a phase generator comprising said second plurality of switches, said phase generator being configured to provide a time varying voltage level to one terminal of each of said pump capacitors, wherein said phase generator is configured to generate a voltage level for at least one pump capacitor in a first charge-transfer path using a voltage from a pump capacitor in a second charge-transfer path. 
     
     
       16. An apparatus comprising a switched-capacitor power-converter that comprises first and second pluralities of switches and gate-driving circuits corresponding to said switches in said first plurality of switches, said gate-driving circuits being configured to rely on charge on pump capacitors to cause said switches from said first plurality of switches to transition between states, wherein, said switched-capacitor power-converter undergoes clocked operation that consists of consecutive clock cycles during each of which a switch from said second plurality of switches connects to a first pump capacitor from the pump capacitors and then a first switch from said first plurality of switches connects to said first pump capacitor. 
     
     
       17. The apparatus of  claim 16 , wherein, when said switch from said second plurality of switches connects to said first pump capacitor, said first pump capacitor begins to charge. 
     
     
       18. The apparatus of  claim 16 , wherein said switch from said second plurality of switches connects to both said first pump capacitor and a second pump capacitor, and wherein, after said switch from said second plurality of switches has closed, a second switch from said first plurality of switches connects to a second pump capacitor. 
     
     
       19. The apparatus of  claim 16 , wherein while said switch from said second plurality of switches is connected to said first pump capacitor, a second pump capacitor is being discharged. 
     
     
       20. An apparatus comprising a switched-capacitor power-converter that comprises first and second pluralities of switches and gate-driving circuits corresponding to said switches in said first plurality of switches, said gate-driving circuits being configured to rely on charge stored on pump capacitors to cause said switches from said first plurality of switches to transition between states, wherein, said switched-capacitor power-converter undergoes clocked operation that consists of consecutive clock cycles, each of which includes a portion during which at most a second switch from said second plurality of switches is connected to said pump capacitors. 
     
     
       21. An apparatus comprising:
 a switched-capacitor power-converter comprising an input port and an output port, a first and a second plurality of switches to be interconnected with a plurality of capacitors, and gate-driving circuits, a particular gate-driving circuit of the gate-driving circuits to correspond to a switch from the first plurality of switches,   wherein the particular gate-driving circuit uses charge from a selected donor capacitor of the plurality of capacitors to operate a corresponding one of the switches from the first plurality of switches,   wherein the first plurality of switches comprises a first switch and the second plurality of switches comprises a second switch,   wherein, during clocked operation of the switched-capacitor power-converter, the first plurality of switches transitions between different states, a particular state of the different states to correspond to a particular interconnection of the plurality of capacitors,   wherein, during the clocked operation of the switched-capacitor power-converter, the first switch closes to establish a connection with a first donor capacitor of the plurality of capacitors,   wherein, prior to the first switch closing, the second switch closes, and   wherein the first donor capacitor is to be at least partially charged by the time the first switch closes.   
     
     
       22. The apparatus of claim 21, wherein the first donor capacitor is to be charged upon closure of the second switch. 
     
     
       23. The apparatus of claim 21, wherein the first donor capacitor is to be pre-charged by the time the first switch closes. 
     
     
       24. The apparatus of claim 21, wherein the donor capacitor comprises a pump capacitor. 
     
     
       25. The apparatus of claim 21, wherein the donor capacitor comprises a voltage-following capacitor. 
     
     
       26. The apparatus of claim 21, wherein the selected donor capacitor comprises the first donor capacitor. 
     
     
       27. The apparatus of claim 21, and further comprising a controller to generate control signals, the control signals to include at least a first plurality of drive signals and a second plurality of drive signals, wherein the first plurality of drive signals to facilitate contemporaneous closure of the first plurality of switches upon closure of the second switch, and wherein the second plurality of drive signals to facilitate contemporaneous closure of the second plurality of switches upon closure of an additional switch of the second plurality of switches. 
     
     
       28. The apparatus of claim 27, wherein the first plurality of drive signals and the second plurality of drive signals are non-overlapping. 
     
     
       29. The apparatus of claim 21, wherein the first plurality of switches comprises at least a first subset of switches and a second subset of switches, wherein switches in the first subset of switches to open and close together at times that differ from times at which switches in the second subset to open and close together. 
     
     
       30. The apparatus of claim 29, wherein the second switch is to be synchronized with the switches in the first subset of switches. 
     
     
       31. The apparatus of claim 21, wherein the first switch and the second switch to close concurrently. 
     
     
       32. The apparatus of claim 21, wherein the first switch to close after or prior to closure of the second switch. 
     
     
       33. The apparatus of claim 21, wherein the clocked operation to include a fixed time interval between closure of the second switch and closure of the first switch. 
     
     
       34. An apparatus comprising:
 a switched-capacitor power-converter having a first plurality of switches and a second plurality of switches, the first plurality of switches to comprise a first subset of switches and a second subset of switches; and   a plurality of gate drivers coupled to corresponding switches of the first or the second plurality of switches to facilitate one or more state transitions of the corresponding switches based, at least in part, on charge stored on respective capacitors, a particular capacitor of the respective capacitors to be coupled to a negative node of a corresponding gate driver of the plurality of gate drivers,   wherein the switched-capacitor power-converter to carry out a clocked operation via consecutive clock cycles,   wherein, during the clocked operation, the first and the second subsets of switches to close concurrently and the second subset of switches to open prior to opening of all switches in the first plurality of switches, and   wherein the clocked operation to implement a time interval during which signals with respect to the first and the second plurality of switches are non-overlapping.   
     
     
       35. The apparatus of claim 34, wherein the time interval to occur between the one or more state transitions. 
     
     
       36. The apparatus of claim 34, wherein the respective capacitors comprise one or more donor capacitors. 
     
     
       37. The apparatus of claim 34, wherein the respective capacitors comprise one or more voltage-following capacitors. 
     
     
       38. The apparatus of claim 34, wherein the respective capacitors comprise one or more pump capacitors. 
     
     
       39. The apparatus of claim 34, wherein the first or the second plurality of switches to include one or more Zener-type diodes. 
     
     
       40. The apparatus of claim 34, wherein, during the clocked operation, a voltage across the one or more Zener-type diodes to be respectively clamped to a substantially constant voltage. 
     
     
       41. The apparatus of claim 34, and further comprising an inductive element to facilitate at least partial control of a charge flow within the switched-capacitor power-converter.