A 3.3 V 6-Bit Current-Steering Digital-to-Analog Converter Using Organic Thin-Film Transistors on a Flexible Polyimide Substrate

This paper presents a 3.3 V 6-bit current-steering digital-to-analog converter (DAC) fabricated using organic thin-film transistors (TFTs) on a flexible polyimide substrate. The DAC achieves an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{INL}_{\max}$</tex> of 1.18 LSB and a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{DNL}_{ \max}$</tex> of -2.08 LSB without calibration. The conversion gain <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\text{LSB}}/\mathrm{I}_{\text{LSB}}$</tex> is about 10 kΩ, which is 2.85 times higher compared to an organic-TFT-based DAC based on the same circuit design but different substrate as well as transistor material and architecture. An interconnection solution is provided by metal pre-patterning on polyimide foil, so the electrical signals to and from the TFT circuits are fanned-out and can be conveniently connected to, e.g., sensors or silicon chips on or outside the foil.