G Maiellaro

High-Gain Operational Transconductance Amplifiers in a Printed Complementary Organic TFT Technology on Flexible Foil

This paper presents the design and experimental results of advanced analog blocks manufactured in a printed complementary organic TFT technology on flexible foil. Operational transconductance amplifiers exhibiting open-loop gain from 40 to 50 dB and gain-bandwidth product from 55 Hz to 1.5 kHz have been implemented by using different circuit topologies. An extensive amplifier characterization in both time and frequency domain (i.e., gain, gain-bandwidth product, phase margin, settling time, harmonic distortion) has been carried out, which demonstrates the performance of the adopted technology in analog circuit implementations. Finally, a 40-dB 1.5-kHz amplifier has been employed in a switched capacitor comparator that proved fully functionality up to input frequency of 50 Hz.

A 4b ADC manufactured in a fully-printed organic complementary technology including resistors

Organic transistors (OTFTs) can be printed on thin plastic substrates to obtain mechanically flexible large-area electronics with high throughput. Examples of applications include sensor-augmented RFIDs fabricated on the packaging of retail items and smart surfaces integrating sensors or actuators. Printed OTFTs have been used to design circuits [1-4], however, these implementations have been mainly limited to digital circuits or large-area switch matrices. A major challenge in the design of printed circuits is the relatively high variability in the characteristics of the OTFTs, which is caused by the low degree of spatial correlation typical of printing processes. A relatively high rate of hard faults is also typical in printed electronics (at the state of the art, yield is acceptable only for a circuit complexity of ~100 transistors).

Ambient Light Organic Sensor in a Printed Complementary Organic TFT Technology on Flexible Plastic Foil

This paper presents an organic sensor for ambient light monitoring fabricated on flexible plastic foil. The sensor exploits an organic photodiode whose photocurrent is linearly converted into an output voltage by a transconductance operational amplifier in a feedback configuration. The photodiode is based on an inkjet printed bulk heterojunction blend of P3HT/PCBM sandwiched between Au and Al electrodes, whereas the amplifier is implemented in a printed complementary organic TFT technology. Both the photodiode and the amplifier were fully characterized in stand-alone configuration. Then, the response of the assembled sensor was measured by using a commercial 12-V halogen lamp as light source. Experimental data demonstrated that the sensor is able to provide a linear detection of the incident light intensity up to 11000 lux.

High performance printed N and P-type OTFTs for complementary circuits on plastic substrate

This paper presents a printed organic complementary technology on flexible plastic substrate with high performance N and P-type Organic Thin Film Transistors (OTFTs), based on small-molecule organic semiconductors in solution. Challenges related to the integration of both OTFT types in a common complementary flow are addressed, showing the importance of surface treatments. Data on single devices and elementary complementary digital circuits (inverters and ring oscillators) are presented, demonstrating that a robust and reliable flow with high electrical performances can be established for printed organic devices.

Design of analog and digital building blocks in a fully printed complementary organic technology

The paper presents several analog and digital building blocks designed using OTFT devices manufactured in a fully-printed complementary organic technology. Circuit performance and parametric variability are simulated based on a model developed specifically for this technology. Fully-static logic gates and flip-flops as well as a low-area dynamic flip-flop enabled by the use of complementary OTFTs are measured, showing good agreement with simulations. A comparator exploiting offset cancellation techniques achieves a measured offset of less than 200mV. In addition, small-sized envelope detectors are measured at the HF RFID frequency (13.56MHz), to demonstrate the high frequency performance of the OTFTs. All these circuits are building blocks for the realization of a printed RFID tag.