Conclusions - Analog Organic Electronics - page 161

the integrated transistors, also the possibility to integrate passive components in the
technology is explored.
The third and largest part of this research work is the implementation and the
demonstration of multiple analog and mixed-signal building blocks. This part is cov-
ered by Chaps. 3 - 6 , which each discuss the implementation and the measurement
results of one building block of the proposed organic smart sensor system architec-
ture.
The differential amplifier, in Chap. 3 , is the first analog building block that is inves-
tigated. First a defensive design methodology is applied to a single-stage differential
amplifier, focusing on both high gain and high reliability of the amplifier. Simulation
results regarding the reliability and measurement results of the performance of this
amplifier are presented. Furthermore, the design and the measurements of a 3-stage
opamp is presented, which employs high-pass filters as a throughput between the
consecutive stages. In order to overcome those high-pass filters, an improved archi-
tecture is presented of a single-stage amplifier that enables the direct connection of
consecutive stages and measurements of both the single-stage amplifier and a 2-stage
DC connected opamp are presented.
The knowledge about amplifier design is applied to a more complex building
block, i.e. an ADC, in Chap. 4 . First a study of the possible ADC architecture families
is carried out and their feasibility in organic electronics technology is examined. As
a conclusion of this study the

ADC is preferred over other architectures for its
low variability and for the flexible trade-off between speed and accuracy. Then the
implementations of a 1 st -order and a 2 nd -order ADC on foil are elucidated and

a measured accuracy of 26.5dB is presented.
The sensor is the building block of the smart sensor system that determines the
core function of the system. Integrated sensors are the subject of Chap. 5 . The possible
sensors and their application field are discussed first. Subsequently the implementa-
tion of both a 1D and a 2D 4

4 touch pad are presented. Both are capacitive sensors
which are based on the series connection of capacitors created when a finger is
located on top of the sensor. The variable capacitance is measured through a current
mirror and a known output capacitor. The sensor read-out has a measured sample
rate of 1.5kS/s. According to simulations an interpolated accuracy is obtained of
0.3mm in a total range of 35mm.
The most atypical building block of the proposed organic smart sensor system is
the DC-DC up-converter, presented in Chap. 6 . This building block is the answer to a
direct need for bias voltages, higher than the power supply voltage and lower than the
ground voltage, in the implementations of the other building blocks discussed in this
work. In a profound survey the optimal up-converter architecture is looked for and it
has turned out that a Dickson converter has the lowest complexity implementation in
organic electronics technology. Three designs of integrated Dickson converters are
included in this chapter and their measurement results have been presented. Finally,
it has been demonstrated that the implemented converter is able to drive the desired
bias pin of the 2-stage opamp with the desired voltage of 35V.

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