Stéphane BURIGNAT started his research carrier in the field of physics of devices successively at the INSA de Lyon, the CNRS at the Ecole Centrale de Lyon, the Université catholique de Louvain.
Rapidly, his researches focused on characterization, modeling and simulation of emerging devices such as sub-32 nm ultra-thin body and BOX SOI transistors, thin film memories, evaluation and implementation of emerging nanodevices into new functionalities in a more than Moore perspective and design of elementary circuit implementing emerging nanodevices.
From November 2009 to August 2013, Stéphane BURIGNAT worked as a post-doctoral fellow at the ELIS laboratory of the Gent University, together with Pr.Alexis De Vos, who first developped the "Reversible Computing Electronics" thematic at UGent.
Stéphane BURIGNAT's main research activities focused on the "physical implementation of reversible circuits".
This work was done in the framwork of the "bilateral Danish-Belgian Micro Power" project sponsored, as a strategic research project by the Commission on Strategic Growth Technologies (strategiske vaekstteknologier) of the Danish ministry for research technology and innovation.
This work was done in a close research collaboration with the informatics department (DIKU) of the Copenhagen University (Danmark) and the Computer Architecture Group of Univerity of Bremen.
See also my research pages.
During his time at UGent, Stéphane BURIGNAT brought several major contributions to the "physical implementation of reversible circuits" field.
He designed and successfully tested one 4-bits reversible ripple-carry adder, the so-called "Cuccaro adder" and the world-first 3-bits reversible H264/AVC video encoder. He also supervised the design and test of the world-first reversible Arithmetic Logic Unit designed and tested by Michael Thomsen from DIKU.
The 4 bits cuccaro adder gave very good results in both direction (forward-adder and backward-subtractor) either by simulations and by measurements (standard pulses and adiabatic signal).
With the 4 bits cuccaro adder, Stéphane BURIGNAT demonstrated the superiority of the use of triangular adiabatic signal compared to classical rectangular shape pulses for driving the reversible chips in both direction (forward-adder and backward-subtractor in that specific case), either by simulations and by measurements (standard pulses and adiabatic signal). The results of this study have been presented and awarded at the MIXDES 2011 edition held on 16th-18th June 2011 at Gliwice in Poland (see also his research pages).
During his master thesis work under the supervision of Stéphane BURIGNAT, Michał Klimczak, successfully designed several Printed Circuit Boards (PCBs). These testing boards allowed to interface the reversible chips with a standard FPGA embedded on a Spantan-3E Xilinx test board, proving that interfacing the reversible CMOS technology with the standard CMOS restoring technology can be done in an easy way at the small cost of 12 extra transistors for each bit of data, while keeping the reversibility (calculation direction) as a programable information. This solution, (the programming of the FPGA being developped by Michael Thomsen from DIKU), has been presented at the Reversible Computation Workshop (RC 2011) held on July 4th-5th, 2011, in Gent and is published in Springer‘s Lecture Notes in Computer Science (LNCS).
During his master thesis work under the supervision of Stéphane BURIGNAT, Mariusz Olczak successfully perform an extended study on the size limit of reversible circuits in order to evaluate how large and complex a reversible circuit can be. This study showed a strong dependency of the maximun number of cascaded gates with the frequency. It also showed that sinusoidal adiabatic signals allow to push away the limits by increasing the number of possibly cascaded gate by 40 %. These results have also been presented at the Reversible Computation Workshop (RC 2011) and the article published in Springer‘s Lecture Notes in Computer Science (LNCS) as well.
The 264/AVC coder fabricated with the support of IMEC/Europractice/mini@sic in ON Semiconductor 0.35µm technology has been tested and gives very promissing results. The shape of the signals appears to be of best quality than even the Cuccaro adder.
This can be explained by the fact that the delays between signals are reduced in the video chip, leading to a better synchronisation of the computation flow (let precise that our reversible CMOS circuit's computation flow is asynchronous).
A third chip has been fabricated in ON Semiconductor 0.35µm technology. It is a cascade of Cuccaro Adder performing an addition followed by a subtraction performing a do-undo function such that output is equal to input. Two cascade lines of different length are embedded in this chip. The cascade length can be selected by a selection bit.
This chip allowed to study the impact of the reversible circuit depth (length) on the reversible computation and its impact on performances. A model for complexity of reversible chips has been proposed.
Two extra circuits have been favricated in UMC 130 nm and UMC 65 nm respectively.
The UMC 65 nm has been financed by the FWO Vlaanderen through the "Krediet aan Navorser" n°1501412N.
They are composed of one reversible full-adder circuits and one conventional full-adder circuit, both on the same chip. This will allow, in one hand, to compare the reversible circuits with conventional CMOS technology regarding performance and consumtion, and in the other hand, to evaluate the impact of the size reduction on the performances and consumption of reversible circuits. The four circuits (2 reversible circuits and 2 conventional restoring circuits) are working properly and first results are very promissing.
The reversible circuits show a consumption inferior to 1 pJ by transistor and by computation cycle and a minimal energy recovering ratio of 70 %