Realization of charge pump circuits using polymer semiconductors

Abstract

In this thesis, design methodology and test results of a polymer charge pump circuit built using polymer semiconductors are presented. The charge pump is built using basic lithography techniques, in which solution processed polymer semiconductor materials are used instead of inorganic semiconductors. The polymer charge pump circuit, consisting of diodes and capacitors, converts an applied alternating voltage signal to a direct current voltage level, performing as a power supply for other devices such as logic blocks. The polymer charge pump is an important step in building wireless polymer electronic circuits such as polymer RFID tags, where power needs to be transmitted wirelessly. Polymer diodes, which are used in the charge pump circuit, are fabricated in a vertical gold/poly(3-hexylthiophene)/aluminum (Au/P3HT/Al) structure. The diodes are initially characterized at various environmental conditions to find optimal operation parameters. Typical unpackaged vertical polymer diodes have a turn-on voltage of 6V. A vertical polymer diode with 2 mm x 0.5 mm area can deliver 1mA at a forward bias of 7V. The charge pump is designed by the guidance of the limitations revealed in the characterization phase of the diodes. The fabricated charge pump is operated with a sinusoidal input voltage of 10V peak amplitude at 100 Hz frequency, producing 7.2V DC at its output node. Cells of charge pumps can be cascaded in order to achieve larger DC voltage levels to be obtained.