Clock Gating

VLSI Concept · Timing

Clock Gating

Don't toggle the clock into logic that isn't doing anything.

Clock gating inserts a gate (an integrated clock-gating cell, ICG) that blocks the clock from reaching a block of flip-flops when that block isn't needed this cycle — cutting dynamic power because unused logic simply doesn't switch. It's one of the single biggest power-saving techniques in modern chip design.

Typical savingsCan cut dynamic power on gated blocks by 30-50%+ when idle often.

Why it mattersMost of a chip is idle most of the time — gating the clock to idle logic is close to "free" power savings.

Common mistakeGating logic incorrectly and accidentally gating away a state update the design actually needed — a functional bug, not just a power one.

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