Non-Volatile Wideband Frequency Tuning of a Ring-Oscillator by Charge Trapping in High-k Gate Dielectric in 22nm CMOS

Abstract

Process and parametric variation negatively impact the performance and yield of analog and digital circuits in advanced nodes. To alleviate this effect, we propose a technique to electrically adjust the threshold voltage of CMOS transistors in a post-fabrication setting in a non-volatile manner. This technique, which relies on self-heating assisted trapping of charge in high-k gate dielectric (e.g. HfOx) used in advanced CMOS nodes, does not require any extra fabrication step. In this letter, we use charge trapping for wideband non-volatile frequency tuning of a ring oscillator. We have demonstrated that the frequency of the ring oscillator can shift from 2075MHz to 1746MHz, when a supply voltage of 0.8V is used. This work serves as a foundation for non-volatile tuning, reconfiguration, and obfuscation of chips and IP blocks. The chip was fabricated in GlobalFoundries 22nm Fully-Depleted Silicon-on-Insulator (FDSOI) CMOS process.