P-173L: Late-News Poster: A 2.2-inch QVGA System-on-Glass LCD Using P-Type Low Temperature Poly-Silicon Thin Film Transistors

Abstract

We have developed a P-type 2.2" QVGA LCD panel with integrated level shifters, shift registers, DC-DC converter, and demultiplexer for mobile application. We also have proposed a novel P-type level shifter to decrease the voltage amplitude of input control signals to fulfill the low power consumption requirement. Besides, we also have integrated a P-type DC-DC converter on the panel to supply the power for the panel. Therefore, the voltage amplitude of control logic signals for our P-type panel can be reduced to 5V, and the IC architecture can be greatly simplified. IntroductionP-type low temperature poly-silicon (LTPS) process has the ability to provide more cost competitiveness than LTPS CMOS process. On the other hand, one merit of LTPS thin film transistor (TFT) is the ability to integrate the peripheral circuits on the panel due to its high current driving capability [1] [2]. Therefore, some studies start to focus on P-type circuit integration try to merge these two merits [3]- [7]. However, to adopt P-type process will affect the integration degree of peripheral circuits because of the power consumption issue. Otherwise, the additional clock signals in different phases [3][5] or redundant voltage source [4] has to be provided from the system to suppress the steady current. However, the fore-mentioned methods will increase the design complexity and power consumption of the external IC, which will limit the application of P-type panels in mobile field. Therefore, to develop a low-power and low-voltage platform for P-type panel application is an indispensable way to enjoy the good of P-type process without bearing the low integration drawback.In this work, we have proposed a 2.2" QVGA P-type panel with the integrated shift registers, level shifters, demultiplexer, and DC-DC converter. We also have proposed a novel low power Ptype level shifter. Through integrating this level shifter on the panel, the voltage amplitude of control signals can be greatly reduced without adding any redundant control signal or voltage source. As a result of this, the voltage amplitude of the external IC control signals can be down to 5 Volt without increasing the design complexity of the external IC. Moreover, we also have integrated a P-type negative voltage DC-DC converter on the substrate. Therefore, the size of the IC can benefit by removing the area-consuming level shifter and the negative voltage DC-DC converter from the glass. The peripheral circuit integration level of this P-type panel can compete with the CMOS TFT panel for mobile application. As a result, this 2.2 inch QVGA panel can not only have the merit of P-type process cost competitiveness, but also have the same circuit integration level as the CMOS TFT panel. Architecture of the LCD PanelThe block diagram in figure 1 (a) shows the architecture of the LCD. A P-type negative voltage DC-DC converter, shift registers, demultiplexer, and level shifters are integrated on a 2.2-inch QVGA (240x320) panel. Comparing with the previous works, the proposed 2.2-inch P-type pa...

59.3: Bridged‐grain (BG) Eximer Laser Annealing (ELA) Polycrystalline Silicon Thin Film Transistors (TFTs)

“…It is well known that the LTPS has the potential for peripheral circuits to realize system on panel (SOP) due to the higher mobility than a-Si TFTs. To reduce the manufacture cost and mask number, a lot of PMOS circuit for display have been proposed, including shift registers, level shifters, demultiplexers, and DC-DC converter [3]. Thus low cost, high performance and reliable LTPS processing technologies are greatly required [4].…”

(Invited) Bridged-grain (BG) Polycrystalline Silicon Thin Film Transistors (TFTs)

“…It is well known that the LTPS has the potential for peripheral circuit integration to realize system on panel (SOP) due to the higher mobility than a-Si TFTs. To reduce the manufacture cost and mask number, a lot of PMOS circuits for display have been proposed, including shift registers, level shifters, demultiplexers, and DC-DC converter [2]. Thus low cost, high performance and reliable LTPS processing technologies are greatly required [3].…”

“…Plots of ln(I ds /((V gs -V fb )/V ds ) vs 1/(V gs -V fb )2 for the n-type normal ELA and BG ELA TFTs…”

Implementation of delta—sigma analog‐to‐digital converter in LTPS process

“…To gain the advantages of SOP applications, some researchers had reported the integration of all control and driving circuits into the display panel. [4][5][6] An 8-bit CPU containing 13,000 TFTs on glass substrate was reported to demonstrate the feasibility of SOP. 7 In Ref.…”