Feedback control for hybrid regulator including a buck converter and a switched capacitor converter

Abstract

A feedback system that can control hybrid regulator topologies that have multiple converters or regulators connected in series is described. The hybrid regulator can include at least two regulators: a switched inductor regulator and a switched-capacitor regulator. The feedback system can simplify feedback design for the hybrid regulator that can include multiple converter stages and can control the feedback to improve the efficiency of a hybrid regulator.

We claim: 
     
       1. A voltage regulator system comprising:
 a hybrid regulator configured to convert an input voltage to an output voltage, wherein the hybrid regulator comprises a plurality of voltage regulators including at least a switched-inductor regulator and a switched-capacitor regulator, 
 wherein the switched-inductor regulator is configured to provide a non-zero amount of charge for a first portion of a first switching period and deliver no charge in a second portion of the first switching period until a subsequent cycle, thereby providing a first predetermined amount of charge per the first switching period, and 
 wherein the switched-capacitor regulator is configured to provide a second predetermined amount of charge per a second switching period; and 
 a first feedback system configured to: 
 compare the output voltage to a reference voltage to determine a first operating frequency for the switched-inductor regulator; 
 determine a second operating frequency for the switched-capacitor regulator based on the first predetermined amount of charge provided by the switched-inductor regulator per the first switching period and the second predetermined amount of charge per the second switching period; 
 cause the switched-inductor regulator to operate at the first operating frequency, and 
 cause the switched-capacitor regulator to operate at the second operating frequency; and 
 a second feedback system that is configured to determine a difference between a parasitic voltage drop and a target voltage drop of the switched-capacitor regulator and cause the switched-inductor regulator to adjust current provided to the switched-capacitor regulator based on the difference. 
 
     
     
       2. The voltage regulator system of  claim 1 , wherein the first feedback system is configured to cause the switched-inductor regulator to operate at the first operating frequency by providing a first periodic signal having the first operating frequency to the switched-inductor regulator. 
     
     
       3. The voltage regulator system of  claim 2 , wherein the first feedback system comprises a frequency divider that is configured to receive a second periodic signal generated by the a feedback control and to generate the first periodic signal having the first operating frequency, and wherein the first feedback system is configured to provide the second periodic signal to the switched-capacitor regulator. 
     
     
       4. The voltage regulator system of  claim 1 , wherein the switched-inductor regulator comprises a multi-phase switched-inductor regulator having a plurality of regulator cells, and wherein the first feedback system is configured to cause the switched-inductor regulator to operate at the first operating frequency by providing a plurality of periodic signals having the first operating frequency to the switched-inductor regulator, wherein the plurality of periodic signals are out-of-phase from one another. 
     
     
       5. The voltage regulator system of  claim 1 , wherein the first feedback system comprises a feedback control that is configured to generate a first periodic signal, based on the reference voltage and the output voltage, having the second operating frequency. 
     
     
       6. The voltage regulator system of  claim 1 , wherein the second feedback system is configured to cause the switched-inductor regulator to adjust the current provided to the switched-capacitor regulator by adjusting one or more of the first switching period, an active period, and a duty cycle D of the switched-inductor regulator. 
     
     
       7. The voltage regulator system of  claim 1 , wherein the first operating frequency is a fraction of the second operating frequency. 
     
     
       8. The voltage regulator system of  claim 1 , further comprising a plurality of bypass switches, wherein one of the bypass switches is configured to couple an input node of a first voltage regulator and an output node of a second voltage regulator in the hybrid regulator. 
     
     
       9. An electronic system comprising:
 a load chip comprising a power domain, wherein the power domain comprises an input voltage terminal and a ground terminal; and 
 a voltage regulator system of  claim 1 , wherein the voltage regulator system is configured to provide the output voltage of the hybrid regulator to the input voltage terminal of the load chip. 
 
     
     
       10. A method of providing an output voltage based on an input voltage, the method comprising:
 providing a hybrid regulator configured to convert the input voltage to the output voltage, wherein the hybrid regulator comprises a plurality of voltage regulators including at least a switched-inductor regulator and a switched-capacitor regulator, wherein the switched-inductor regulator is configured to provide a non-zero amount of charge for a first portion of a first switching period and deliver no charge in a second portion of the first switching period until a subsequent cycle of the switched-inductor regulator, and wherein the switched-capacitor regulator is configured to provide a second predetermined amount of charge per a second switching period; and 
 comparing, at a first feedback system, output voltage to a reference voltage to determine a first operating frequency for the switched-inductor regulator; 
 determining, by the first feedback system, a second operating frequency for the switched-capacitor regulator based on the first predetermined amount of charge provided by the switched-inductor regulator per the first switching period and the second predetermined amount of charge provided by the switched-capacitor regulator per a second switching period; 
 causing, by the first feedback system, the switched-inductor regulator to operate at the first operating frequency; 
 causing, by the first feedback system, the switched-capacitor regulator to operate at the second operating frequency; and  
 determine, by a second feedback system, a difference between a parasitic voltage drop and a target voltage drop of the switched-capacitor regulator and cause the switched-inductor regulator to adjust current provided to the switched-capacitor regulator based on the difference. 
 
     
     
       11. The method of  claim 10 , wherein causing the switched-inductor regulator to operate at the first operating frequency comprises providing a first periodic signal having the first operating frequency to the switched-inductor regulator. 
     
     
       12. The method of  claim 11 , further comprising:
 receiving, at a frequency divider in the first feedback system, the a second periodic signal generated by the a feedback control; 
 generating, by the frequency divider, the first periodic signal having the first operating frequency; and 
 providing the second periodic signal to the switched-capacitor regulator. 
 
     
     
       13. The method of  claim 10 , wherein the switched-inductor regulator comprises a multi-phase switched-inductor regulator having a plurality of regulator cells, and wherein causing the switched-inductor regulator to operate at the first operating frequency comprises providing a plurality of periodic signals having the first operating frequency to the switched-inductor regulator, wherein the plurality of periodic signals are out-of-phase from one another. 
     
     
       14. The method of  claim 10 , further comprising generating, at a feedback control in the first feedback system, a first periodic signal having the second operating frequency based on the reference voltage and the output voltage. 
     
     
       15. The method of  claim 10 , wherein causing the switched-inductor regulator to adjust the current provided to the switched-capacitor regulator is performed by adjusting one or more of: the first switching period, an active period, and/or a duty cycle D of the switched-inductor regulator. 
     
     
       16. The method of  claim 10 , wherein the hybrid regulator system comprises a plurality of bypass switche, wherein one of the bypass switches is configured to couple an input node and an output node of the one of the voltage regulators in the hybrid regulator. 
     
     
       17. A system for controlling a hybrid regulator that is configured to convert an input voltage to an output voltage, wherein the hybrid regulator comprises a plurality of voltage regulators including at least a switched-inductor regulator and a switched-capacitor regulator, the system comprising:
 a first feedback system configured to:
 compare the output voltage to a reference voltage to determine a first operating frequency for the switched-inductor regulator; 
 determine a second operating frequency for the switched-capacitor regulator based on (i) a first predetermined amount of charge provided by the switched-inductor regulator per a first switching period and (ii) a second predetermined amount of charge provided by the switched capacitor regulator per a second switching period, wherein the first predetemined amount of charge includes a non-zero amount of charge for a first portion of the first switch period and no charge in a second portion of the first switching period until a subsequent cycle; 
 cause the switched-inductor regulator to operate at the first operating frequency, and 
 cause the switched-capacitor regulator to operate at the second operating frequency; and 
   a second feedback system that is configured to:
 determine a difference between a parasitic voltage drop and a target voltage drop of the switched-capacitor regulator and cause the switched-inductor regulator to adjust current provided to the switched-capacitor regulator based on the difference.  
   
     
     
       18. The system of claim 17, wherein the first feedback system is configured to cause the switched-inductor regulator to operate at the first operating frequency by providing a first periodic signal having the first operating frequency to the switched-inductor regulator.  
     
     
       19. The system of claim 18, wherein the first feedback system comprises a frequency divider that is configured to receive a second periodic signal generated by a feedback control and to generate the first periodic signal having the first operating frequency, and wherein the feedback system is configured to provide the second periodic signal to the switched-capacitor regulator.  
     
     
       20. The system of claim 17, wherein the systems further comprises the switched inductor regulator and wherein the switched-inductor regulator comprises a multi-phase switched-inductor regulator having a plurality of regulator cells, and wherein the first feedback system is configured to cause the switched-inductor regulator to operate at the first operating frequency by providing a plurality of periodic signals having the first operating frequency to the switched-inductor regulator, wherein the plurality of periodic signals are out-of-phase from one another.  
     
     
       21. The system of claim 17, wherein the first feedback system comprises a feedback control that is configured to generate a first periodic signal, based on the reference voltage and the output voltage, having the second operating frequency.  
     
     
       22. The system of claim 17, wherein the second feedback system is configured to cause the switched-inductor regulator to adjust the current provided to the switched-capacitor regulator by adjusting one or more of the first switching period, an active period, and a duty cycle D of the switched-inductor regulator.  
     
     
       23. The system of claim 17, wherein the first operating frequency is a fraction of the second operating frequency.  
     
     
       24. The system of claim 17, wherein the system further comprises a plurality of bypass switches, wherein one of the bypass switches is configured to couple an input node of a first voltage regulator and an output node of a second voltage regulator in the hybrid regulator.  
     
     
       25. The system of claim 17, wherein the first feedback system is connected to the switched-inductor regulator and the switched-capacitor regulator.  
     
     
       26. The system of claim 17, wherein the second feedback system is connected to the switched-inductor regulator and the switched-capacitor regulator.  
     
     
       27. A method for controlling a hybrid regulator that is configured to convert an input voltage to an output voltage, wherein the hybrid regulator comprises a plurality of voltage regulators including at least a switched-inductor regulator and a switched-capacitor regulator, the method comprising:
 comparing, at a first feedback system, the output voltage to a reference voltage to determine a first operating frequency for the switched-inductor regulator;   determining, by the first feedback system, a second operating frequency for the switched-capacitor regulator based on (i) a first predetermined amount of charge provided by the switched-inductor regulator per a first switching period and (ii) a second predetermined amount of charge provided by the switched capacitor regulator per a second switching period, wherein the first predetemined amount of charge includes a non-zero amount of charge for a first portion of the first switch period and no charge in a second portion of the first switching period until a subsequent cycle;   causing, by the first feedback system, the switched-inductor regulator to operate at the first operating frequency;   causing, by the first feedback system, the switched-capacitor regulator to operate at the second operating frequency; and   determine, by a second feedback system, a difference between a parasitic voltage drop and a target voltage drop of the switched-capacitor regulator and cause the switched-inductor regulator to adjust current provided to the switched-capacitor regulator based on the difference.    
     
     
       28. The method of claim 27, wherein causing the switched-inductor regulator to operate at the first operating frequency comprises providing a first periodic signal having the first operating frequency to the switched-inductor regulator.  
     
     
       29. The method of claim 28, further comprising:
 receiving, at a frequency divider in the first feedback system, a second periodic signal generated by a feedback control;   generating, by the frequency divider, the first periodic signal having the first operating frequency; and   providing the second periodic signal to the switched-capacitor regulator.    
     
     
       30. The method of claim 27, wherein causing the switched-inductor regulator to adjust the current provided to the switched-capacitor regulator is performed by adjusting one or more of: the first switching period, an active period, and/or a duty cycle D of the switched-inductor regulator.  
     
     
       31. The method of claim 27, wherein the hybrid regulator system comprises a plurality of bypass switches, wherein one of the bypass switches is configured to couple an input node and an output node of the one of the voltage regulators in the hybrid regulator.  
     
     
       32. The method of claim 27, wherein the first feedback system is connected to the switched-inductor regulator and the switched-capacitor regulator.  
     
     
       33. The method of claim 27, wherein the second feedback system is connected to the switched-inductor regulator and the switched-capacitor regulator.  
     
     
       34. The method of claim 27, wherein the switched-inductor regulator comprises a multi-phase switched-inductor regulator having a plurality of regulator cells, and wherein causing the switched-inductor regulator to operate at the first operating frequency comprises providing a plurality of periodic signals having the first operating frequency to the switched-inductor regulator, wherein the plurality of periodic signals are out-of-phase from one another.  
     
     
       35. The method of claim 27, further comprising generating, at a feedback control in the first feedback system, a first periodic signal having the second operating frequency based on the reference voltage and the output voltage.  
     
     
       36. A voltage regulator system comprising:
 a plurality of voltage converters arranged in series between an input voltage and an output voltage, wherein the plurality of voltage converters includes a switched-capacitor regulator and a switched-inductor regulator;   at least one bypass switch arranged to selectively couple an input node of at least one of the plurality of voltage converters and an output node of the at least one of the plurality of voltage converters; and   a feedback system that is configured to determine a difference between a parasitic voltage drop and a target voltage drop of the switched-capacitor regulator and cause the switched-inductor regulator to adjust current provided to the switched-capacitor regulator based on the difference.    
     
     
       37. The voltage regulator system of 36, wherein the at least one bypass switch is controlled based on at least one of the following: the input voltage, the output voltage, a conversion ratio of a switched capacitor regulator in the plurality of voltage converters, and a parasitic switched capacitor voltage drop of the switched capacitor regulator.  
     
     
       38. The voltage regulator system of 36, wherein a separate bypass switch is provided for each of the plurality of voltage converters.  
     
     
       39. The voltage regulator system of 36, wherein the at least one bypass switch includes two bypass switches that collectively couple an input node of one converter stage and an output node of another converter stage.  
     
     
       40. The voltage regulator system of 36, wherein at least one of the plurality of voltage converters comprises a reconfigurable converter that has multiple inputs and multiple outputs, and one or more switch matrices that can choose an input from the multiple inputs and an output from the multiple outputs.  
     
     
       41. The voltage regulator system of 40, wherein the reconfigurable converter comprises a switched capacitor converter that can reconfigure a step-down ratio of the switched capacitor converters across a plurality of values including at least two of 2:1, 3:1, 4:1, and 5:1.