Fully printed electronics on flexible substrates: High gain amplifiers and DAC

Abstract

We propose a novel simple Fully-Additive printing process, involving only depositions, for realizing printed electronics circuits/systems on flexible plastic films. This process is Green (non-corrosive chemicals), On-Demand (quick-to-print), Scalable (large-format printing) and Low-Cost vis-à-vis Subtractive printing, a complex deposition-cum-etching process that otherwise requires expensive/sophisticated specialized IC-like facilities and is Un-Green, Not-On-Demand, Un-scalable and High-Cost. The proposed Fully-Additive process features printed transistors with high (∼1.5 cm2/Vs) semiconductor carrier-mobility, ∼3× higher than competing state-of-the-art Fully-Additive processes and comparable to Subtractive processes. Furthermore, passive elements including capacitors, resistors, and inductors, and two metal-interconnect layers are likewise Fully-Additive printed–to our knowledge, to-date the only Fully-Additive process capable of realizing complex circuits/systems on flexible plastic films. Several analog and mixed-signal circuits are demonstrated, including proposed and conventional differential amplifiers, and a charge-redistribution 4-bit digital-to-analog converter (DAC). The proposed amplifier embodies a novel positive-cum-negative feedback to simultaneously significantly improve the gain and reduce susceptibility to process variations. To improve the speed and reduce the area of the DAC, the parasitic capacitors therein are exploited. The Fully-Additive proposed amplifier and DAC are benchmarked against reported realizations (all Subtractive-based processes), and are shown to be highly competitive despite its realization based on the simple low-cost proposed Fully-Additive process.