Overview
While clock gating stops dynamic power (switching), power gating addresses leakage power (static power). It involves using a 'sleep transistor' to disconnect a functional block from the power supply entirely.
Comparison with Clock Gating
- Clock Gating: Fast to enable/disable, saves dynamic power, but the block still 'leaks' electricity.
- Power Gating: Slower to wake up, saves both dynamic and static power, effectively turning the block 'off'.
Implementation
Used extensively in mobile SoCs to turn off unused CPU cores, GPU clusters, or specialized accelerators when they are not needed, extending battery life.