Hierarchical Power Distribution with 20 Power Domains in 90-nm Low-Power Multi-CPU Processor

Hierarchical power distribution with a power tree has been developed. The key features are power tree management rules and a distributed common power-domain implementation. The hierarchical power distribution supports a fine-grained power gating with dozens of power domains, which is analogous to a fine-grained clock gating. Leakage currents of a 1,000,000-gate power domain were effectively reduced to 1/4,000 in multi-CPU SoCs with minimal area overhead.