High Speed Amplifier Design for Thin Film Transistors

Abstract

Large Area Electronics (LAE) offers the ability to create physically-expansive, form-fitting arrays of transducers. Such systems can be used to implement physically- integrated sensing that preserves structure in the data derived from human interactions with physical objects. LAE relies on the thin film transistor (TFT), which can be fabricated onto a variety of different substrates (e.g. plastic or glass) by virtue of its low-temperature processing. However, TFTs are inherently low performing as a result of high device capacitance and low mobility. Nevertheless, advances in their fabrication has meant that LAE is now moving into the gigahertz region. The ZnO TFT fabricated by the Large Area Electronics Research Group at Princeton University is one such transistor that exhibits improved performance. With an fT and fmax greater than 1GHz, the question then becomes: at how high of a frequency can the ZnO TFT be operated at? This thesis investigates the design of a high frequency amplifier for the ZnO TFT by comparing the gain and power consumption of common-source amplification against distributed amplification. The latter can achieve gain across a wider bandwidth than the former, and is the first distributed amplifier to be demonstrated in Large Area Electronics.