Romano Torres 9th January 2013

DC/DC Converters To convert a dc input voltage Vs into a dc output voltage Vo; To regulate the dc output voltage against load and line variations; To reduce the ac voltage ripple on the dc output voltage below the required level; To provide isolation between the input source and the load; From reference [10]

Applications Electronic devices: Internal sub-circuits require different voltage levels; Low battery voltage level needed. Photovoltaic panels: Increase the voltage level of electric current produced.

Step-Down Buck Converter Image from reference [10]

Step-Up Boost Converter Image from reference [10]

Buck-Boost Converter Image from reference [10]

Cuk Converter Image from reference [10]

Transparency CapacitorsResistors Images from reference [5]

Transparent thin-film transistors In 2003 appear the first successful reports of TTFT using ZnO as channel layer material [1] [3] [8]. In 2004, K. Nomura et al. report the successful fabrication of TTFT with a-GIZO (amorphous gallium- indium-zinc-oxide) [9].

TTFT device structure Staggered bottom-gate Image from reference [10]

TFT operation modes Pre-saturation: Vgs>Vt & Vds<Vgs-Vt Saturation: Vds>Vgs-Von Cut-off: Vgs<Vt No current flow.

a-GIZO TFT limitations p-type devices with poor semi-conductor characteristics; Threshold voltage shift due DC-bias; Source and drain contacts resistance influence the TFT characteristics;

a-GIZO TFT limitations Temperature: Oxygen vacancy. Image from reference [6]

a-GIZO TFT limitations Light: Image from reference [7]

Transparency Problems with inductors: Poor conductance; High parasitic resistance; Low quality factor.

Voltage multipliers Due the various problems with transparent inductors, we propose use voltage multipliers; How does it work?

Proposed positive DC/DC Converter Images from reference [4]

Proposed negative DC/DC Converter Images from reference [4]

Transparent photovoltaic panels Image from reference [2]

References [1] P. F. Carcia, R. S. McLean, M. H. Reilly and G. Nunes, "Transparent ZnO thin-film transistor fabricated by RF magnetron sputtering", Applied Physics Letters, vol.82, no.7, pp , Feb [2] C. Chen, L. Dou, R. Zhu, C. Chung, T. Song, Y. Zheng, S. Hawks, G. Li, P. Weiss, and Y. Yang, Visibly transparent polymer solar cells produced by solution processing, in American Chemical Society vol. 6 no.8, 2012, pp [3] R. L. Hoffman, B. J. Norris and J. F. Wager, "ZnO-based transparent thin-film transistors", Applied Physics Letters, vol.82, no.5, pp , Feb [4] S. Hong, DC-DC Converters using Indium Gallium Zinc Oxide thin film transistors for mobile display applications, in Japanese Journal of Applied Physics, [5] D. Keszler, R. Presley and J. Wager, Transparent Electronics. New York, USA: Springer, [6] S. Kuk, S. Lee, S. Kim, B. Kim, S. Park, J. Kwon, and M. Han, Light-induced hysteresis of In– Ga–Zn–O thin-film transistors with various temperatures, in IEEE Electron Device Letters vol. 33 no. 9, 2012, pp [7] S. Lee, S. Kim, Y. Lee, W. Lee, K. Yoon, J. Kwon, and M. Han, The effect of the photo-induced carriers on the reliability of Oxide TFTs under various intensities of light, in IEEE Electron Device Letters vol. 33 no. 2, 2012, pp [8] S. Masuda, K. Kitamura, Y. Okumura, S. Miyatake, H. Tabata and T. Kawai, "Transparent thin film transistors using ZnO as an active channel layer and their electrical properties", Journal of Applied Physics, vol.93, no.3, pp , Feb [9] K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano, and H. Hosono, Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors, in Nature vol. 432, 2004, pp.488–492. [10] M. Rashid, DC DC Converters, in Power Electronics Handbook. San Diego, USA: Academic Press, 2001, pp