Time delayed converter reshuffling
Dynamic power management techniques and voltage converter architectures are described to provide a secure and efficient on-chip power delivery system. In aspects of the embodiments, converter-gating is used to adaptively turn individual interleaved switched-capacitor stages of a voltage converter on and off based on workload information to improve voltage conversion efficiency. Further, as a countermeasure against machine learning based differential power analysis attacks, for example, control signals provided to a number of the interleaved switched-capacitor stages are delayed to reduce the risk of low power trace entropy (PTE). A higher PTE value is maintained regardless of the phase difference between an attacker's sampling rate and the operating frequency, providing an additional layer of security.
1. A switched capacitor voltage converter, comprising:
a plurality of switched capacitor stages configured to provide power from a power source to a circuit load;
a feedback loop electrically coupled to an output of the plurality of switched capacitor stages;
stage control logic configured to determine an active number of the plurality of switched capacitor stages based on an output signal from the feedback loop;
scrambling logic configured to randomly adjust an activity pattern for control signals provided to the plurality of switched capacitor stages based on the active number of the plurality of switched capacitor stages to disrupt a correlation between the power provided from the power source to the circuit load; and
time delay logic configured to delay at least a subset of the control signals provided to the plurality of switched capacitor stages.
2. The switched capacitor voltage converter of claim 1 , wherein:
the scrambling logic comprises an N-bit random scrambler, wherein N is a number of the plurality of switched capacitor stages;
a first subset of the control signals is provided to a first subset of the plurality of switched capacitor stages;
the time delay logic delays a second subset of the control signals to provide a delayed subset of control signals; and
the delayed subset of control signals is provided to a second subset of the plurality of switched capacitor stages.
3. The switched capacitor voltage converter of claim 1 , wherein:
the scrambling logic comprises an N/2-bit random scrambler, wherein N is a number of the plurality of switched capacitor stages;
the control signals are provided to a first subset of the plurality of switched capacitor stages;
the time delay logic delays the control signals to provide a delayed subset of control signals; and
the delayed subset of control signals is provided to a second subset of the plurality of switched capacitor stages.
4. The switched capacitor voltage converter of claim 3 , wherein the scrambling logic comprises an N/P-bit random scrambler, wherein N is a number of the plurality of switched capacitor stages and P is a multiple of 2.
5. The switched capacitor voltage converter of claim 1 , wherein the time delay logic increases a power trace entropy (PTE) of an input power profile of the switched capacitor voltage converter.
6. The switched capacitor voltage converter of claim 1 , further comprising a low dropout regulator coupled to an output of the plurality of switched capacitor stages.
7. The switched capacitor voltage converter of claim 1 , wherein the stage control logic is further configured to adjust the active number of the plurality of switched capacitor stages based on a load demand.
8. The switched capacitor voltage converter of claim 1 , wherein the stage control logic is further configured to:
reconfigure at least one of the plurality of switched capacitor stages that is inactive to provide a decoupling capacitor at an output of the switched capacitor voltage converter; and
reconfigure at least one of the plurality of switched capacitor stages to increase a charge transfer ratio of the switched capacitor voltage converter.
9. A method of providing power from a power source to a circuit load using a switched capacitor voltage converter, comprising:
sampling, through a feedback loop, an output voltage of the switched capacitor voltage converter provided to the circuit load, the switched capacitor voltage converter having a plurality of switched capacitor stages;
determining an active number of the plurality of switched capacitor stages based on the output voltage;
randomly adjusting, by scrambling logic, an activity pattern for control signals provided to the plurality of switched capacitor stages based on the active number of the plurality of switched capacitor stages to disrupt a correlation between the power provided from the power source to the circuit load; and
delaying at least a subset of the control signals provided to the plurality of switched capacitor stages.
10. The method of claim 9 , wherein:
a first subset of the control signals is provided to a first subset of the plurality of switched capacitor stages;
the delaying comprises delaying a second subset of the control signals to provide a delayed subset of control signals; and
the delayed subset of control signals is provided to a second subset of the plurality of switched capacitor stages.
11. The method of claim 9 , wherein:
the control signals are provided to a first subset of the plurality of switched capacitor stages;
the delaying comprises delaying the control signals to provide a delayed subset of control signals; and
the delayed subset of control signals is provided to a second subset of the plurality of switched capacitor stages.
12. The method of claim 9 , wherein the scrambling logic comprises an N/P-bit random scrambler, wherein N is a number of the plurality of switched capacitor stages and P is a multiple of 2.
13. The method of claim 9 , wherein the delaying increases a power trace entropy (PTE) of an input power profile of the switched capacitor voltage converter.
14. The method of claim 9 , further comprising reconfiguring at least one of the plurality of switched capacitor stages that is inactive to provide a decoupling capacitor at an output of the switched capacitor voltage converter.
15. The method of claim 9 , further comprising reconfiguring at least one of the plurality of switched capacitor stages to increase a charge transfer ratio of the switched capacitor voltage converter.
16. A switched capacitor voltage converter, comprising:
a plurality of switched capacitor stages;
stage control logic configured to determine an active number of the plurality of switched capacitor stages;
scrambling logic configured to randomly adjust an activity pattern for control signals provided to the plurality of switched capacitor stages based on the active number of the plurality of switched capacitor stages; and
time delay logic configured to delay at least a subset of the control signals provided to the plurality of switched capacitor stages, wherein the time delay logic increases a power trace entropy (PTE) of an input power profile of the switched capacitor voltage converter.
17. The switched capacitor voltage converter of claim 16 , wherein the scrambling logic comprises an N/P-bit random scrambler, wherein N is a number of the plurality of switched capacitor stages and P is a multiple of 2.
18. The switched capacitor voltage converter of claim 16 , wherein:
the scrambling logic comprises an N-bit random scrambler, wherein N is a number of the plurality of switched capacitor stages;
a first subset of the control signals is provided to a first subset of the plurality of switched capacitor stages;
the time delay logic delays a second subset of the control signals to provide a delayed subset of control signals; and
the delayed subset of control signals is provided to a second subset of the plurality of switched capacitor stages.
19. The switched capacitor voltage converter of claim 16 , wherein:
the scrambling logic comprises an N/2-bit random scrambler, wherein N is a number of the plurality of switched capacitor stages;
the control signals are provided to a first subset of the plurality of switched capacitor stages;
the time delay logic delays the control signals to provide a delayed subset of control signals; and
the delayed subset of control signals is provided to a second subset of the plurality of switched capacitor stages.
20. The switched capacitor voltage converter of claim 19 , wherein the stage control logic is further configured to:
reconfigure at least one of the plurality of switched capacitor stages that is inactive to provide a decoupling capacitor at an output of the switched capacitor voltage converter; and
reconfigure at least one of the plurality of switched capacitor stages to increase a charge transfer ratio of the switched capacitor voltage converter.