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

• Published in: IEEE electron device letters Vol. 42; no. 1; pp. 110 - 113
• Main Authors: Nouri, Sepideh, Iyer, Subramanian S.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Analog circuits; Broadband; charge-trapping; circuit tuning; CMOS; Digital electronics; Frequency measurement; high-k dielectric; Logic gates; Nodes; non-volatile; oscillator; Programming; Reconfiguration; Ring oscillators; Silicon-on-insulator; SOI; Threshold voltage; Transistors; Trapping; Tuning
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2020.3036080

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.