During the last decades, organic semiconductor technology on flexible substrate is attracting the interest of both academia and industrial communities since it is considered a very promising alternative to silicon technology in those applications where low cost, flexibility, and capability to cover large surfaces are required. The great advantage of organic thin-film transistor (OTFT) technology is the direct fabrication of circuits on low-cost plastic foils by using both low processing temperatures and printing methods that guarantee cost-efficient production. Several applications were faced by using OTFTs, such as flexible displays, RFID tags and organic processors. Such technologies also allow the integration on the same substrate of different kinds of organic sensors (i.e., light, temperature, pressure, humidity, pH, biosensors, etc.) in order to implement fully-integrated flexible organic smart sensors. Despite these interesting developments, most OTFT processes still feature only p-type transistors, while very few complementary OTFT (C-OTFT) platforms have been developed. Of course, the availability of a reliable process flow featuring both p-type and n-type transistors is now of utmost importance to advance in industrial applications development. Indeed, complementary organic technology would allow the implementation of complex digital circuits with higher yield and lower current consumption, as well as an increased reliability in mixed analog/digital circuits. Research efforts on organic electronics have been mainly addressed towards digital circuits, while there is still a serious lack of significant results in the analog field. This lacuna hampers the advance towards the implementation of fully-integrated mixed-signal organic systems, including analog front-ends, signal conditioning, and/or analog-to-digital conversion (i.e., RFIDs, smart sensors, etc.). In this thesis work analog and digital basic building blocks (i.e., inverters, static and dynamic logic gates, static and dynamic flip-flops, ring oscillator, differential gain stage, and rectifier/envelope detector) fabricated using a fully-printed organic complementary technology on flexible substrate are presented. The performance of the rectifier/envelope detector are explored up to 13.56-MHz thus demonstrating that adopted technology is suitable for the implementation of a flexible organic RFID tag. Moreover, design of complex analog building blocks (i.e., folded-cascode transconductance amplifier, 2-stage OTA, stacked-mirror OTA and switched-capacitor comparator) are also faced since the research on complementary organic analog circuits is still at very beginning and they are essential for enabling the implementation of fully-integrated mixed-signal systems (i.e., smart sensor interfaces, wireless communication systems, etc.). The measured performance of the single-stage folded-cascode transconductance amplifier is the best-in-class for complementary OTFT technologies on flexible substrate. Finally, design and experimental results of the first fully-integrated flexible organic light sensor are also presented.

Analog and Digital Circuits in a Complementary Organic TFT Technology on Flexible Substrate / Maiellaro, Giorgio. - (2012 Dec 07).

Analog and Digital Circuits in a Complementary Organic TFT Technology on Flexible Substrate

MAIELLARO, GIORGIO
2012-12-07

Abstract

During the last decades, organic semiconductor technology on flexible substrate is attracting the interest of both academia and industrial communities since it is considered a very promising alternative to silicon technology in those applications where low cost, flexibility, and capability to cover large surfaces are required. The great advantage of organic thin-film transistor (OTFT) technology is the direct fabrication of circuits on low-cost plastic foils by using both low processing temperatures and printing methods that guarantee cost-efficient production. Several applications were faced by using OTFTs, such as flexible displays, RFID tags and organic processors. Such technologies also allow the integration on the same substrate of different kinds of organic sensors (i.e., light, temperature, pressure, humidity, pH, biosensors, etc.) in order to implement fully-integrated flexible organic smart sensors. Despite these interesting developments, most OTFT processes still feature only p-type transistors, while very few complementary OTFT (C-OTFT) platforms have been developed. Of course, the availability of a reliable process flow featuring both p-type and n-type transistors is now of utmost importance to advance in industrial applications development. Indeed, complementary organic technology would allow the implementation of complex digital circuits with higher yield and lower current consumption, as well as an increased reliability in mixed analog/digital circuits. Research efforts on organic electronics have been mainly addressed towards digital circuits, while there is still a serious lack of significant results in the analog field. This lacuna hampers the advance towards the implementation of fully-integrated mixed-signal organic systems, including analog front-ends, signal conditioning, and/or analog-to-digital conversion (i.e., RFIDs, smart sensors, etc.). In this thesis work analog and digital basic building blocks (i.e., inverters, static and dynamic logic gates, static and dynamic flip-flops, ring oscillator, differential gain stage, and rectifier/envelope detector) fabricated using a fully-printed organic complementary technology on flexible substrate are presented. The performance of the rectifier/envelope detector are explored up to 13.56-MHz thus demonstrating that adopted technology is suitable for the implementation of a flexible organic RFID tag. Moreover, design of complex analog building blocks (i.e., folded-cascode transconductance amplifier, 2-stage OTA, stacked-mirror OTA and switched-capacitor comparator) are also faced since the research on complementary organic analog circuits is still at very beginning and they are essential for enabling the implementation of fully-integrated mixed-signal systems (i.e., smart sensor interfaces, wireless communication systems, etc.). The measured performance of the single-stage folded-cascode transconductance amplifier is the best-in-class for complementary OTFT technologies on flexible substrate. Finally, design and experimental results of the first fully-integrated flexible organic light sensor are also presented.
7-dic-2012
analog and digital circuits, fully-printed organic complementary TFT technology on flexible substrate
Analog and Digital Circuits in a Complementary Organic TFT Technology on Flexible Substrate / Maiellaro, Giorgio. - (2012 Dec 07).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/586576
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