Power Management

Which describes power gating?

  1. AStopping only the clock supply to circuit blocks
  2. BSwitching off the power supply to unused circuit blocks, eliminating nearly all their leakage power too
  3. CDoubling the supply voltage to speed up processing
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Answer: B. Switching off the power supply to unused circuit blocks, eliminating nearly all their leakage power too

Clock gating stops switching and so cuts dynamic power, but leakage continues as long as power is connected. Power gating turns off a large transistor switch placed between the block and the supply, cutting power itself, so leakage nearly disappears too. Smartphone SoCs aggressively power off idle CPU cores, GPUs and accelerators.

  • A. That is clock gating.
  • B. Correct. Its key feature is cutting static power too.
  • C. It is a power-saving technique.
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More Power Management questions

  1. Which correctly pairs a caveat of power-gated blocks with its countermeasure?
  2. Which correctly compares clock gating and power gating?
  3. In power gating, why are a block's power switches often turned on gradually in sequence rather than all at once?
  4. What is the role of the isolation cells placed between a powered-off block and running blocks?
  5. What is the role of a level shifter inserted when passing signals between two blocks running at different supply voltages?