Digital Signal Processing Reference
In-Depth Information
enhance the behavior and the reliability of circuits is in motion. At the technology
level, there is the ability to deposit a backgate on top of a transistor that influences
its threshold voltage. At the circuit level, the backgate steering technique has been
proven to improve the reliability of circuits. It is the combination of improvements at
both research levels that demands for very high and very lowbias voltages and enables
the niche topic of organic DC-DC converters. The application field that demands for
bias voltages rather than for power delivery at the outputs creates a whole different
context for the DC-DC converters than the more common context present in standard
Si
technology. The atypical organic transistor technologies with their unusual and
limited set of available components complicate the implementation of all kinds of
circuits, also DC-DC converters. That is why a profound investigation is required
into the feasibility of the implementation of several up-converter architectures in the
organic electronics technologies.
In this chapter first an overview was given of the application field and three appli-
cations were highlighted: Digital circuit behavior is improved by biasing backgates
to a voltage. Moreover analog circuits can be biased with their inputs and outputs at
the same voltage level when a high bias voltage is available. Finally also a very low
biasing voltage is beneficial for biasing transistors in the linear region. From these
applications a set of specifications was deduced that are to be fulfilled in order to
make organic DC-DC converters beneficial.
Next a broader comparison was provided between several types of DC-DC con-
verters towards their applicability. Inductive converters are not applicable. At the
moment the Dickson converter architecture is the best fit for application in organic
technology. It scores better than series-parallel, voltage doubler and Fibonacci archi-
tectures for complexity and switch implementation.
Subsequently three Dickson converter designs were presented with their imple-
mentation, simulation results and measurement results.
Finally a discussion about the very low power efficiency of the presented convert-
ers was provided. This low power efficiency was mostly caused by the limitations of
the unipolar circuit technology. Because of their distinct application field, however,
organic DC-DC converters were considered an added value to organic circuit design.
References
Myny K, Beenhakkers MJ, van Aerle NAJM, Gelinck GH, Genoe J, DehaeneW, Heremans P (2011)
Unipolar organic transistor circuits made robust by Dual-Gate technology. IEEE J Solid-State
Circ 46(5):1223-1230
Van Breussegem T, Steyaert M (2010) A fully integrated 74% efficiency 3.6 V to 1.5 V 150 mW
capacitive point-of-load DC/DC-converter. In: Proceedings of the ESSCIRC 2010. pp 434-437
Wens M, Cornelissens K, Steyaert M (2007) A fully-integrated 0.18m CMOS DC-DC step-up
converter, using a bondwire spiral inductor. In: 33rd European Solid State Circuits Conference
ESSCIRC 2007. pp 268-271
Wens M, Steyaert MSJ (2011) A fully integrated CMOS 800-mW Four-Phase semiconstant
ON/OFF-Time Step-Down converter. IEEE Trans Power Electron 26(2):326-333
