Implementation and verification practices of DVFS and power gating

Abstract

Reducing the power supply voltage is an effective technique to reduce dynamic power. Power shut-off (PSO) is also a well-known approach to reduce leakage power. In practice, one may employ multi-supply voltage or dynamic voltage and frequency scaling (DVFS) techniques accompanied with power gating and multi-depth sleep modes to reduce both of dynamic and leakage power consumption. As the voltage domains (power domains) and sleep modes (power modes) are increased dramatically, it is difficult to plan interface logics such as level shifters and isolation cells completely by manual for each power domain. In this paper, we present an interface planning methodology, and take a DVFS and power gating design with over 50 power domains and 80 power modes to demonstrate the verification challenges and our solutions. Besides, we propose a “seamless” interface control circuit for PSO and DVFS designs. By using the circuit, the designs in the power on domain don't feel any data change when the opposite power domain is powered off.