Process Variation Sensing and Compensation Employing a Ring Oscillator-Based Architecture in SkyWater 130nm Technology

This paper presents a fully digital process variation compensator designed and validated using the open-source SkyWater 130nm PDK. The architecture integrates a current-starved ring oscillator, a frequency-to-digital converter (FDC), and a digital comparator to detect and classify standard process corners in real time. A digitally controlled ramp generator serves as a test to validate the compensation mechanism under extracted post-layout conditions. Simulations across SS, TT, FF, SF, and FS corners demonstrate reliable corner classification and successful compensation of analog mismatch, with all corrected outputs converging to a reference response. Operation is validated within a temperature window of 10°C-40°C to ensure robust classification without frequency band overlap. The results confirm the suitability of the proposed architecture for adaptive, variation-tolerant ICs fabricated through open-source PDKs and Multi Project Wafer (MPW) flows.