Power Management

Which describes the idea behind adaptive voltage scaling (AVS)?

  1. ARunning every chip at a high voltage set for the slowest chip
  2. BChanging voltage randomly every time
  3. CMeasuring each chip's speed and temperature on chip and approaching the minimum voltage at which it works, trimming wasted voltage margin
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Answer: C. Measuring each chip's speed and temperature on chip and approaching the minimum voltage at which it works, trimming wasted voltage margin

Manufacturing variation makes some chips of the same product fast and others slow. Running every chip at a voltage that works even for the slowest wastes power on fast chips, whose voltage is higher than necessary. With AVS, on-chip ring oscillators or delay-measuring circuits check actual speed, and voltage is adjusted to just what that chip needs, accounting for temperature and aging.

  • A. That is the traditional, margin-heavy approach.
  • B. Voltage is not changed randomly.
  • C. Correct. It exploits chip-to-chip variation.
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More Power Management questions

  1. Which is NOT a reason chips need margin in their supply voltage?
  2. What is an advantage of placing the regulators that generate CPU supply voltages inside the chip or package rather than on the motherboard (integrated regulators)?
  3. Why is the energy-delay product (EDP) sometimes preferred over energy alone in evaluating low-power designs?
  4. What is the closest efficiency of a linear regulator (LDO) producing 1.0 V from a 1.8 V input (ignoring the regulator's own quiescent current)?
  5. A device drawing 300 mA on average runs from a 3000 mAh battery. Roughly how many hours does it run (ignoring voltage drop and similar)?