Kyushu University [Yusuke Matsunaga (Associate Professor) Faculty of Information Science and Electrical Engineering, Department of Advanced Information Technology]

Department of Computer Science and Communication Engineering
Graduate School of Information Science and Electrical Engineering

Department of Electrical Engineering and Computer Science
School of Engineering

System LSI Research Center

Doctor of Engineering

Design Automation for VLSI

Research interests: EDA for VLSI, esspecially logic synthesis and verification, high-level synthesis, test

Asia/South Pacific representative of Design Automation Conference Executive Committee
Secretary of VLD research group of IEICE
Asia South-Pacific Design Automation Conference technical program committee vice-chair

Research Interests

Research on design automation for VLSI systems
keyword : VLSI, Sytem on a Chip, EDA, CAD
2001.04Developping a methodolgy and EDA algorithms for designing large and complex System LSI's correctly and efficiently..

Current and Past Project

To research and develop fundamental technologies for the VLSI system than can guarantee high reliability and high security.

Academic Activities

Papers

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1.	松永裕介, An Accelerating Technique for SAT-based ATPG, IPSJ Trans. System LSI Design Methodology, http://doi.org/10.2197/ipsjtsldm.10.39, 10, 39-44, 2017.03, This paper describes an accelerating technique for SAT based ATPG (automatic test pattern generation). The main idea of the proposed algorithm is representing more than one test generation problems as one CNF formula with introducing control variables, which reduces CNF generation time. Furthermore, learnt clauses of previously solved problems are effectively shared for other problems solving, so that the SAT solving time is also reduced. Experimental results show that the proposed algorithm runs more than 3 times faster than the original SAT-based ATPG algorithm..
2.	松永裕介, Accelerating SAT-Based Boolean Matching for Heterogeneous FPGAs Using One-Hot Encoding and CEGAR Technique , IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E99-A, 7, 1374-1380, 2016.07, This paper describes two speed-up techniques for Boolean matching of LUT-based circuits. One is one-hot encoding technique for variables representing input assignments. Though it requires more variables than existing binary encoding technique, almost all added clauses using one-hot encoding are binary clauses, which are suitable for efficient Boolean constraint propagation. The other is CEGAR (counter example guided abstraction refinement) technique which reduces the CPU time significantly. With both techniques, we can solve Boolean matching problem with 9 input function in 20 milliseconds on average, which is faster than the existing algorithms more than one order of magnitude. .
3.	松永裕介, A test pattern compaction method using SAT-based fault grouping, IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E99-A, 12, 2302-2309, 2015.12, This paper presents a test pattern compaction algorithm applicable for large scale circuits. The proposed methods formalizes the test pattern compaction problem as a problem finding minimum set of compatible fault groups. Also, an efficient algorithm checking compatibility of fault group is proposed. The experimental results show that the proposed algorithm achieves similar or better results against a couple of existing methods, especially for middle circuits. .
4.	松永裕介, Synthesis Algorithm for Parallel Index Generator, IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E97, 12, 2451-2458, 2014.12, The index generation function is a multi-valued logic function which checks if the given input vector is a registered or not, and returns its index value if the vector is registered. If the latency of the operation is critical, dedicated hardware is used for implementing the index generation functions. This paper proposes a method implementing the index generation functions using parallel index generator. A novel and efficient algorithm called ‘conflict free partitioning’ is proposed to synthesize parallel index generators. Experimental results show the proposed method outperforms other existing methods. Also, A novel architecture of index generator which is suitable for parallelized implementation is introduced. A new architecture has advantages in the sense of both area and delay..
5.	Taeko Matsunaga, Shinji Kimura, 松永裕介, An Exact Approach for GPC-Based Compressor Tree Synthesis, IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E96, 12, 2553-2560, 2013.12, Multi-operand adders that calculate the summation of more than two operands usually consist of compressor trees, which reduce the number of operands to two without any carry propagation, and carry-propagate adders for the two operands in the ASIC implementation. Compressor trees that consist of full adders and half adders cannot be implemented efficiently on LUT-based FPGAs, and carry-chains or dedicated structures have been utilized to produce multi-operand adders on FPGAs. Recent studies indicate that compressor trees can be implemented efficiently on LUTs using Generalized Parallel Counters (GPCs) as the building blocks of compressor trees. This paper addresses the problem of synthesizing compressor trees based on GPCs. Based on the observation that characteristics such as the area, power, and delay correlate roughly to the total number and the maximum level of GPCs, the target problem can be regarded as a minimization problem for the total number of GPCs and the maximum levels of the GPCs, for which an ILP-based approach is proposed. The key point of our formulation is not to model the problem based on the structures of compressor trees like the existing approach, but instead the compression process itself is used to reduce the number of variables and constraints in the ILP formulation. The experimental results demonstrate the advantage of our formulation in terms of the quality and runtime..
6.	髙田大河, Yoshimura Masayoshi, 松永裕介, Efficient Fault Simulation Algorithms for Analyzing Soft Error Propagation in Sequential Circuits, IPSJ Trans. System LSI Design Methodology, http://dx.doi.org/10.2197/ipsjtsldm.6.127, 6, 127-134, 2013.08, This paper presents two acceleration techniques of fault simulation for analyzing soft error propagation in sequential circuits. One is an exact technique and the other is a heuristic technique. Since these techniques are independent on how the logic functions of circuits are evaluated, they can be combined with other techniques which accelerate evaluations of the logic functions of circuits, such as event-driven simulation, single pattern parallel fault propagation (SPPFP). Experimental results show that applying the exact technique makes a fault simulator with event-driven simulation and SPPFP 30-143 times faster. A fault simulator with the exact technique finished for several large-scale circuits in 4.6 hours or less, while a fault simulator without the exact technique could not finish for such circuits in 72 hours. Furthermore, applying the heuristic technique makes a fault simulator with the exact technique about 7-17 times faster with only 0.5-2.2% estimation error..
7.	Masayoshi Yoshimura, Yusuke Akamine and Yusuke Matsunaga, An Exact Estimation Algorithm of Error Propagation Probability for Sequential Circuits, IPSJ Trans. System LSI Design Methodology, 10.2197/ipsjtsldm.5.63, 5, 63-70, 2012.02.
8.	Taiga Takata and Yusuke Matsunaga, "A Robust Algorithm for Pessimistic Analysis of Logic Masking Effects in Combinational Circuits, IPSJ Trans. System LSI Design Methodology, 10.2197/ipsjtsldm.5.55, 5, 55-62, 2012.02.
9.	Taeko Matsunaga, Shinji Kimura and Yusuke Matsunaga,, "Multi-Operand Adder Synthesis Targeting FPGAs, IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 10.1587/transfun.E94.A.2579, E94, 12, 2011.12.
10.	Taiga Takata, Yusuke Matsunaga, Efficient Cut Enumeration Heuristics for Depth-Optimum Technology Mapping for LUT-Based FPGAs, IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 96, 12, 3268-3275, 2009.12.
11.	Taeko Matsunaga, Shinji Kimura and Yusuke Matsunaga, Framework for Parallel Prefix Adder Synthesis Considering Switching Activities, IPSJ Transactions on System LSI Design Methodology, Vol. 2, pp.212-221, 2009.09.
12.	Taiga Takata and Yusuke Matsunaga, Area Recovery under Depth Constraint for Technology Mapping for LUT-based FPGAs, IPSJ Transactions on System LSI Design Methodology, Vol. 2, pp.200-211, 2009.09.
13.	Sho Kodama and Yusuke Matsunaga, Binding Refinement for Multiplexer Reduction, IPSJ Transaction on System LSI Design Methodology, 2009.02.
14.	Tsuyoshi Sadakata and Yusuke Matsunaga, A Behavioral Synthesis Method with Special Functional Units, IEICE Trans. on Fundamentals, Vol. E91-A, No. 4, pp. 1084-1091, 2008.04.
15.	Taeko Matsunaga and Yusuke Matsunaga, Timing-Constrained Area Minimization Algorithm for Parallel Prefix Adders, IEICE Trans. on Fundamentals, Vol. E90-A, No. 12, pp.2770-2777, 2007.12.
16.	Tsuyoshi Sadakata and Yusuke Matsunaga, A Simultaneous Module Selection, Scheduling, and Allocation Method Considering Operation Chaining with Multi-Functional Units, IEICE Trans. on Fundamentals, Vol. E90-A, No. 4, pp.729-799, 2007.04.
17.	On boolean mathing algorithm for LUT-type FPGA based on functional decomposition.
18.	Yusuke Matsunaga, An Efficient Algorithm Finding Simple Disjoint Decompositions Using BDDs, IEICE Trans. on Fund., E85A, 12, 2715-2724, E85-A, No. 12, pp. 2715-2724, 2002.12.

Presentations

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1.	Yusuke Matsunaga, Masayoshi Yoshimura, An efficient SAT-attack algorithm against logic encryption, IOLTS2019, 2019.07, This paper presents a novel efficient SAT-attack algorithm for logic encryption. The existing SAT-attack algorithm can decrypt almost all encrypted circuits proposed so far, however, there are cases that it takes a huge amount of CPU time. This is because the number of clauses being added during the decryption increases drastically in that case. To overcome that problem, a novel algorithm is developed, which considers the equivalence of clauses to be added. Experiments show that the proposed algorithm is much faster than the existing algorithm. .
2.	Yusuke Matsunaga, Accelerating SAT-based Boolean matching for heterogeneous FPGAs using one-hot encoding and CEGAR technique, 2015 20th Asia and South Pacific Design Automation Conference, ASP-DAC 2015, 2015.03, This paper describes two speed-up techniques for Boolean matching of LUT-based circuits. One is one-hot encoding technique for variables representing input assignments. Though it requires more variables than existing binary encoding technique, almost all added clauses using one-hot encoding are binary clauses, which are suitable for efficient Boolean constraint propagation. The other is CEGAR (counter example guided abstraction refinement) technique which reduces the CPU time significantly. With both techniques, we can solve Boolean matching problem with 9 input function in 20 milliseconds on average, which is faster than the existing algorithms more than one order of magnitude..
3.	松永裕介, Synthesis Algorithm of Parallel Index Generation Units, Design, Automation & Test in Europe （DATE-2014), 2014.03, [URL], The index generation function is a multi-valued logic function which checks if the given input vector is a registered or not, and returns its index value if the vector is registered. If the latency of the operation is critical, dedicated hardware is used for implementing the index generation functions. This paper proposes a new method implementing the index generation functions. This method requires only one memory access while the existing method requires twice. The proposed method also has an advantage for total memory size against to the existing method..
4.	松永裕介, An Efficient Implementation of The Index Generation Functions, International Workshop on Logic and Synthesis (IWLS2013), 2013.06, [URL], The index generation function is a multi-valued logic function which checks if the given input vector is a registered or not, and returns its index value if the vector is registered. If the latency of the operation is critical, dedicated hardware is used for implementing the index generation functions. This paper proposes a new method implementing the index generation functions. This method requires only one memory access while the existing method requires twice. The proposed method also has an advantage for total memory size against to the existing method. .
5.	髙田大河, Yoshimura Masayoshi, Yusuke Matsunaga, An Efficient Fault Simulation Algorithm for Analyzing Incorrect State Transitions induced by Soft Errors in Sequential Circuits, International Workshop on Logic and Synthesis (IWLS2012), 2012.06, [URL].
6.	髙田大河, Yusuke Matsunaga, A Quantitative Analysis of Soft Error Propagation in Sequential Circuits, (th Workshop on Silicon Errors in Logic - System Effects (SELESE8), 2012.03.
7.	Y. Matsunaga, An Exact and Efficient Algorithms for Disjunctive Decomposition, Synthesis And System Integration of Mixed Technologies (SASMI'98), Oct. 1998.

Educational Activities

- For undergraduate students : having lectures for logic circuits and logic design
- For graduate students: having a lecture for EDA for SOCs

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