49.3: Oxide TFT Scan Driver with Dynamic Threshold Voltage Control

Park, Yong-Sung; Chung, Bo-Yong; Kang, Chul-Kyu; Park, Seoung-Il; Im, Kiju; Jeong, Jae Hoon; Kim, Byung-Hee; Kim, Sang Soo

doi:10.1889/1.3621426

Cited by 13 publications

(12 citation statements)

References 2 publications

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“…Constant positive TG voltage (V TG ) induces a negative shift of the transfer characteristics, thereby enabling a depletion mode of operation [4] a positive shift of the transfer characteristics, enabling an enhancement mode of operation [4]. Various applications using dual-gate TFTs have thus been reported [5]- [9].…”

Section: Introductionmentioning

confidence: 99%

Bulk Accumulation a-IGZO TFT for High Current and Turn-On Voltage Uniformity

Mativenga¹,

An²,

Jang³

2013

IEEE Electron Device Lett.

127

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We present here an amorphous indium-galliumzinc-oxide (a-IGZO) thin-film transistor (TFT) in which the accumulation layer is not only confined to the a-IGZO/gateinsulator interface, but extends the entire depth of the a-IGZO. This bulk accumulation TFT is achieved by the use of topand bottom-gate, that are electrically tied together, resulting in drain current that is over seven times higher than that of a single-gate device, for an a-IGZO thickness of 10 nm. Thus, high drive current is achieved for a relatively small channel width due to bulk accumulation. Furthermore, being independent of carrier scattering at the interface and owing to the bulk accumulation/depletion, the subthreshold swing is always small and turn-on voltage around zero volts with device-to-device uniformity that is much better than that of single-gate TFTs. IndexTerms-Amorphous indium-gallium-zinc-oxide (a-IGZO), bulk accumulation, dual gate, thin-film transistor (TFT).

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Section: Introductionmentioning

confidence: 99%

Bulk Accumulation a-IGZO TFT for High Current and Turn-On Voltage Uniformity

Mativenga¹,

An²,

Jang³

2013

IEEE Electron Device Lett.

127

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“…Even though the single supply implementation with a STT structures has been introduced [9], that shift register cannot avoid increasing power consumption of the large-sized pull-up and pull-down TFTs at the deep depletion-mode operation along with the requirement of some overlap interval. Second, dual gate oxide TFTs are used to shift some internal TFTs of shift registers into enhancement mode by applying some voltage to one of two gate nodes [10]. More complicated process and circuit structure are required, increasing the fabrication cost.…”

Section: Introductionmentioning

confidence: 99%

Depletion Mode Oxide TFT Shift Register for Variable Frame Rate AMOLED Displays

Song

Kang²,

Han³

et al. 2015

IEEE Electron Device Lett.

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This letter demonstrates a shift register circuit at the backplane of depletion mode oxide thin-film transistors (TFTs), which can cover variable frame rates for low-power active matrix organic light emitting diode (AMOLED) displays. The proposed scheme focuses on the stable gate control of a pull-up TFT by securing the charging and discharging paths at the wide operating frequency range. In a prototype high-definition (HD: 1366 × 768) AMOLED panel, it is ensured that fabricated shift registers operate at the wide frame frequency range from 1 to 240 Hz. The measured current consumptions are 30, 4, 6, and 5.8 mA for four clock signals, VGH of 24 V, VGL1 of −6 V, and VGL2 of −14 V at a frame rate of 120 Hz.Index Terms-Depletion mode, oxide TFT, shift register, variable frame rate.

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“…However, because most oxide TFTs are inherently depletionmode devices and the TFT's threshold voltage is shifted over bias stresses, integrated oxide TFT circuits should be able to operate at a wide threshold voltage range from depletion mode to enhancement mode [6]. To cope with the depletion mode issue in integrated gate drivers, two low-level supply voltages were adopted [7], the double gate scheme was applied to the oxide TFT to control the threshold voltage [8], and the floating gate scheme was employed with capacitors [9]. However, [7] operated only with overlap multi-phase clocks, [8] required more complicated fabrication and circuitry, and [9] needed highly intricate operation and circuit structure.…”

Section: Introductionmentioning

confidence: 99%

Robust Two-Phase Clock Oxide TFT Shift Register over Threshold Voltage Variation and Clock Coupling Noises

Nam

Song

2014

ETRI J

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This letter describes a two‐phase clock oxide thin‐film transistor shift register that executes a robust operation over a wide threshold voltage range and clock coupling noises. The proposed circuit employs an additional Q generation block to avoid the clock coupling noise effects. A SMART‐SPICE simulation shows that the stable shift register operation is established for the clock coupling noises and the threshold voltage variation from −4 V to 5 V at a line time of 5 μs. The magnitude of coupling noises on the Q(15) node and Qb(15) node of the 15th stage is respectively −12.6 dB and −26.1 dB at 100 kHz in the proposed circuit, compared to 6.8 dB and 10.9 dB in a conventional one. In addition, the estimated power consumption is 1.74 mW for the proposed 16‐stage shift registers at VTH=−1.56 V, compared to 11.5 mW for the conventional circuits.

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49.3: Oxide TFT Scan Driver with Dynamic Threshold Voltage Control

Cited by 13 publications

References 2 publications

Bulk Accumulation a-IGZO TFT for High Current and Turn-On Voltage Uniformity

Bulk Accumulation a-IGZO TFT for High Current and Turn-On Voltage Uniformity

Depletion Mode Oxide TFT Shift Register for Variable Frame Rate AMOLED Displays

Robust Two-Phase Clock Oxide TFT Shift Register over Threshold Voltage Variation and Clock Coupling Noises

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