Rail-to-Rail Timing Signals Generation Using InGaZnO TFTs For Flexible X-Ray Detector

Autor: Pydi Ganga Bahubalindruni, Bhawna Tiwari, Maria Pereira, Ana Santa, Jorge Martins, Ana Rovisco, Vitor Tavares, Rodrigo Martins, Elvira Fortunato, Pedro Barquinha
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: IEEE Journal of the Electron Devices Society, Vol 8, Pp 157-162 (2020)
Druh dokumentu: article
ISSN: 2168-6734
DOI: 10.1109/JEDS.2020.2971277
Popis: This paper reports on-chip rail-to-rail timing signals generation thin-film circuits for the first time. These circuits, based on a-IGZO thin-film transistors (TFTs) with a simple staggered bottom gate structure, allow row and column selection of a sensor matrix embedded in a flexible radiation sensing system. They include on-chip clock generator (ring oscillator), column selector (shift register) and row-selector (a frequency divider and a shift register). They are realised with rail-to-rail logic gates with level-shifting ability that can perform inversion and NAND logic operations. These logic gates are capable of providing full output swing between supply rails, VDD and VSS, by introducing a single additional switch for each input in bootstrapping logic gates. These circuits were characterised under normal ambient atmosphere and show an improved performance compared to the conventional logic gates with diode connected load and pseudo CMOS counterparts. By using these high-performance logic gates, a complete rail-to-rail frequency divider is presented from measurements using D-Flip Flop. In order to realize a complete compact system, an on-chip ring oscillator (output clock frequency around 1 kHz) and a shift register are also presented from simulations, where these circuits show a power consumption of 1.5 mW and 0.82 mW at a supply voltage of 8 V, respectively. While the circuit concepts described here were designed for an X-ray sensing system, they can be readily expanded to other domains where flexible on-chip timing signal generation is required, such as, smart packaging, biomedical wearable devices and RFIDs.
Databáze: Directory of Open Access Journals