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

This article presents a novel design of high-speed ring oscillator (RO) in ${n}$ -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 $-{t}_{{\text {pd}}}$ 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.