energygating

Energy gating is a technique used in electronics to reduce power consumption in integrated circuits. It works by selectively shutting off power to inactive parts of a chip. This is particularly useful for devices with intermittent workloads, such as mobile phones, where certain components are not constantly in use.

The core principle behind energy gating involves placing switches, often transistors, in the power supply lines to specific circuit blocks. When a block is not needed, these switches are opened, disconnecting it from the power source. This prevents leakage current, which is a small amount of current that flows even when a transistor is supposed to be off, from dissipating power unnecessarily.

Implementing energy gating requires careful design to ensure that power can be restored to the gated blocks quickly and without corrupting their state. This often involves saving the state of the block before powering it down and restoring it upon reactivation. Different levels of granularity exist, from gating entire functional units to gating individual transistors. The trade-off is typically between the amount of power saved and the overhead associated with the gating and de-gating process, which includes the time and power required to manage the switches and restore state. Advanced techniques may use multiple voltage domains or power gating arrays to achieve more sophisticated power management.