High Speed Operational Amplifier using a-InGaZnO TFTs with Negative Capacitance

Rodrigues, R.; Bahubalindruni, Pydi Ganga; Barquinha, Pedro

doi:10.1109/iscas45731.2020.9180659

Cited by 4 publications

(3 citation statements)

References 28 publications

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“…A similar situation exists for TFTs based on semiconducting metal oxides, except that in this case, the performance and stability of n-channel TFTs are far better than those of pchannel TFTs, so that most metal-oxide-TFT-based circuits are designed using exclusively n-channel TFTs. These technology limitations emphasize the importance of advanced unipolar circuit-design techniques to enable high-performance analog [21]- [26] and digital [27]- [38] circuits on flexible substrates.…”

Section: Introductionmentioning

confidence: 99%

Source-Degenerated Schmitt-Trigger-Based High-Performance Digital Logic for Flexible Organic Thin-Film Transistor Technologies

Seifaei¹,

schillinger²,

Prabhu³

et al. 2023

Preprint

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<p>A resistive Schmitt-trigger (RST) logic is proposed. Based on this architecture, a digital cell library was designed, and basic logic-gate architectures, ring oscillators, edge-sensitive D-type flip-flops and a pad-driver cell were fabricated using low-voltage p-channel organic thin-film transistors (TFT) and integrated thin-film carbon resistors on flexible polymeric substrates. Theoretical analysis and experimental characterization of the RST logic architecture indicate improved stability against device-parameter mismatch and charge-carrier-mobility degradation. A small-signal gain of 83 dB and a noise margin of 92 % of half the supply voltage have been measured. Owing to the intrinsic positive-feedback loop of the RST logic, the design of the D-flip-flop enables a substantially smaller footprint and a considerably lower energy dissipation compared to previously reported unipolar organic-TFT-based D-flip-flops.</p>

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Section: Introductionmentioning

confidence: 99%

Source-Degenerated Schmitt-Trigger-Based High-Performance Digital Logic for Flexible Organic Thin-Film Transistor Technologies

Seifaei¹,

schillinger²,

Prabhu³

et al. 2023

Preprint

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“…Research on novel materials, improved fabrication techniques and circuit topologies [1,2] to implement high performance thin film transistor (TFT) based flexible electronic applications is fast progressing. Design-technology interaction at the transistor level, which puts the upper limit on any such performance enhancements needs to be explored first [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Effect of active layer thickness variation on scaling response in a-IGZO thin film transistors under Schottky limited operation

Raj¹,

Tripathi²,

Mahato³

et al. 2021

Semicond. Sci. Technol.

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Active layer thickness variation in highly-doped amorphous indium-gallium-zinc oxide thin film transistors with molybdenum-chromium contacts is studied to reveal parametric dependencies under both channel length and gate-contact overlap length scaling. Devices with thickness variations from 5 nm to 30 nm, channel length variation from 3 µm to 100 µm and gate-contact overlap length variation from 1 µm to 10 µm were fabricated, characterized and analyzed. Analysis from a field effect transistor perspective show typical thickness variation trends where threshold voltage shifts positively, subthreshold slope improves and I on /I off ratio increases as the active layer thickness is scaled down. Peculiar observations like extremely low saturation voltage, insensitivity towards channel length variations, two different slopes in the subthreshold region and peaks in the transconductance characteristics can be explained only by invoking the principle of Schottky transistor operation. Thinner devices exhibit high field Schottky operation with barrier lowering which causes monotonously increasing transconductance, while thicker devices show low field behavior with no barrier lowering signified by peaks with saturated behavior of transconductance. Channel length modulates this dependence of transconductance on thickness. Sensitivity towards gate-contact overlap length scaling increases with thickness. Devices with active layer thickness of 5 nm can withstand overlap length scaling up to 5 µm without transconductance degradation, while devices of 10 nm thickness can withstand overlap length scaling only upto 10 µm. Devices of 30 nm thickness show contact limited operation even at 10 µm overlap length. Conventional FET operating principles cannot explain these observations and the phenomenon of Schottky contact transistor operation has been invoked. The results point towards a thin borderline in low dimensional transistors, differentiating a FET from Schottky contact transistors, through a field dependent barrier lowering mechanism, which is modulated by active layer thickness, channel length and gate contact overlap length.

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“…Because of which, CMOS circuit techniques cannot be adapted directly and new design techniques need to be investigated. Till date many a-IGZO TFT based circuits have been reported on flexible substrates such as amplifiers [11], [12], [13], ring oscillators [14], filters [15], bootstrapping circuit [5] and rectifiers [16]. The work done towards analog-to-digital Converters (ADCs) with oxide TFTs is very limited, though they are critical functional blocks to implement systems of practical importance.…”

Section: Introductionmentioning

confidence: 99%

Mostly Passive Δ - Σ ADC with a-IGZO TFTs for Flexible Electronics

Wadhwa

Bahubalindruni

Correia

et al. 2021

2021 IEEE International Symposium on Circuits and Systems (ISCAS)

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This paper presents a novel mostly passive ∆-Σ ADC using amorphous Indium Gallium Zinc Oxide (a-IGZO) thin-film transistors (TFTs). The ADC circuit consists of passive elements (resistors and capacitors), a novel dynamic comparator, a D-Flip Flop and a pseudo-CMOS BS inverter. In-house oxide TFT model is used for circuit simulations in Cadence environment. The proposed ADC results in effective-numberof-bits (ENOB) of 11.2 bits and a figure-of-merit (FOM) of 0.15 µJ/conversion step at 2 kHz sampling frequency with a 10 V power supply. This circuit would find potential applications in biomedical wearable systems, in which, the ADC is probably the most important block.

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High Speed Operational Amplifier using a-InGaZnO TFTs with Negative Capacitance

Cited by 4 publications

References 28 publications

Source-Degenerated Schmitt-Trigger-Based High-Performance Digital Logic for Flexible Organic Thin-Film Transistor Technologies

Source-Degenerated Schmitt-Trigger-Based High-Performance Digital Logic for Flexible Organic Thin-Film Transistor Technologies

Effect of active layer thickness variation on scaling response in a-IGZO thin film transistors under Schottky limited operation

Mostly Passive Δ - Σ ADC with a-IGZO TFTs for Flexible Electronics

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