High-Speed Ring Oscillator Using Skewed Delay Scheme Integrated by Metal-Oxide TFTs

• Published in: IEEE transactions on electron devices Vol. 67; no. 12; pp. 5526 - 5531
• Main Authors: Xu, Wen-Xing, Chen, Jun-Wei, Zhou, Lei, Xu, Miao, Wang, Lei, Wu, Wei-Jing, Liu, Yu-Rong, Peng, Jun-Biao
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bootstrap; Buffers; Capacitance; Clocks; Delays; High speed; indium-zinc-oxide (IZO) thin-film transistors (TFTs); Inverters; Logic gates; Metal oxides; Oscillators; ring oscillator (RO); Semiconductor devices; skewed delay (SD); Thin film transistors
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2020.3029539

This article presents a novel design of high-speed ring oscillator (RO) in <inline-formula> <tex-math notation="LaTeX">{n} </tex-math></inline-formula>-type-only indium-zinc-oxide (IZO) thin-film transistor (TFT) technology. The proposed ROs combine the advantage of the skewed delay (SD) scheme and the bootstrap inverter to achieve a higher oscillation frequency. The design of improved output buffers with stronger driving capability is also included. For comparison, the proposed seven-stage SD ROs and the conventional bootstrap RO are fabricated on the same glass. It is measured that the oscillation frequencies of the SD ROs with <inline-formula> <tex-math notation="LaTeX">-{t}_{{\text {pd}}} </tex-math></inline-formula> and 0 SD are improved by more than 45% and 25% within the supply voltage ranges from 6 V up to 20 V. In addition, the measured output swings of the proposed boost buffers are improved by more than 50% with input frequencies higher than megahertz.