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 integral non-linearity INL<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of 1.18 LSB (least significant bit) and a differential non-linearity DNL<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of -2.08 LSB without calibration. The conversion gain V<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LSB</sub>/I<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LSB</sub> is about 10 kΩ, which is 2.85 times higher compared to a previously reported organic-TFT-based DAC based on the same circuit design fabricated on a different type of substrate using a different device architecture and a different organic semiconductor for the TFTs. 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.