Adaptive Clocking Using Supply Tracking Clock Modulator With Background-Calibrated Supply Sensitivity

Adaptive clocking (AC) has shown promising results for digital systems when there is a supply droop. However, coping with clock buffer delay and coarsely quantized clock frequency still remains a challenge. To solve these issues, we propose a supply tracking clock modulator placed after the clock buffer, which continuously changes the clock frequency to the supply. A prototype fabricated in 28-nm CMOS allows 36% higher system clock frequency and 25% higher power efficiency in a 15% supply droop, than a normal system without AC.