Gate my clock

Understanding the latch in integrated clock gating cells

This medium-difficulty question tests your understanding of Integrated Clock Gating (ICG) — a critical power-optimization technique in ASIC design where the control logic for gating clock signals must be carefully sequenced to avoid glitches and metastability. It probes whether you understand why a level-sensitive latch is a purposeful exception to the usual prohibition on latches in synchronous design.

Candidates who solve this typically reason about the timing relationship between the enable signal, the clock edge, and the final gated output. The key is recognizing that the latch serves a specific architectural role in stabilizing or capturing the control signal at a precise point in the clock cycle. Strong answers explain the hazard or race condition that the latch prevents, and why that particular timing behavior is necessary for correct gate operation.

• Clock gating enable timing and setup/hold requirements
• Metastability and glitch avoidance in control paths
• Level-sensitive vs. edge-triggered latching in synchronous contexts