I. Introduction
The sanguine projection of the gargantuan growth of printed electronics (PE) from U.S. 15 billion today to U.S. 190 billion [1] within a decade to a large extent assumes that intelligent (embodying analog, mixed-signal, and digital signal processing functionalities) PE circuits and systems can be realized. This also largely assumes that the printing can be realized on low-cost flexible substrates [e.g., polyethylene terephthalate (PET)], and that the printing is low-cost, on-demand, and scalable (large format). The practical realization of these PE circuits and systems, as in traditional silicon electronics, necessitates that the variations (and the associated mismatches) of the active elements are small. The primary parameter of the variations of organic thin-film transistors (OTFTs) is the carrier mobility , and in some cases, the threshold voltage .