Autotuning of Integrated Inductive Voltage Regulator Using On-Chip Delay Sensor to Tolerate Process and Passive Variations

This paper demonstrates autotuning of the coefficients of the feedback loop of an inductive integrated voltage regulator (IVR) using an on-chip delay sensor. The proposed approach improves the effective performance of the digital core under variations in the on-die/package integrated passives and transistor process. A 130-nm CMOS test-chip is designed containing a multisampled 125-MHz IVR with a wirebond inductor, on-die capacitor, and all-digital proportional-integral-differential (PID) controller powering a parallel Advanced Encryption Standard (AES) engine. The autotuning is performed using a Vernier delay line based on-chip delay sensor and an all-digital tuning engine. The measurement results demonstrate up to 5.2% improvement in the maximum operating frequency of the AES core using performance-based autotuning.