An analog organic first-order CT ΔΣ ADC on a flexible plastic substrate with 26.5dB precision

Organic electronics is expected to find commercial applications in flexible displays, RFID tags and smart sensor systems, e.g. for food industry or biomedical applications. Key benefits of the technology are the direct production of transistors and circuits on flexible plastic foils, the possibility to directly integrate sensors, light sources, light detectors, a.o. with the same technology, and the low processing temperatures that warrant cost-efficient production. However, organic electronics technologies suffer from important drawbacks versus silicon based technologies, such as its intrinsically lower mobility, the large parameter variation and a very low intrinsic transistor gain (typically 5). Moreover as active components almost exclusively p-type transistors are available and as passive components only capacitors exist. In place of resistors, we are limited to only linear biased transistors. Work on organic RFID [1,2] and several types of organic sensors [3] has been presented. Analog designs in organic technology are in their infancy: a first differential amplifier with differential-mode gain of 10 was presented in [4]; design considerations for analog designs were discussed in [5]; a comparator was presented in [6]; and a 6-bit D/A converter based on a C-2C chain in [7]. In the present work, we disclose the first ADC designed, fabricated and measured in an organic technology on plastic foil with a fully analog design approach.