Integrated circuit (IC) camouflaging technique has been applied as a countermeasure against reverse engineering (RE). However, its effectiveness is threatened by a boolean satisfiability (SAT) based de-camouflaging attack, which is able to restore the camouflaged circuit within only minutes. As a defense to the SAT-based de-camouflaging attack, a brand new camouflaging strategy (called CamoPerturb) has been proposed recently, which perturbs one minterm by changing one gate’s functionality and then restores the perturbed circuit with a separated camouflaged block, achieving good resistance against the SAT-based attack. In this paper, we analyze the security vulnerabilities of CamoPerturb by illustrating the mechanism of minterm perturbation induced by gate replacement, then propose an attack to restore the changed gate’s functionality, and recover the camouflaged circuit. The attack algorithm is facilitated by sensitization and implication principles in automatic test pattern generation (ATPG) techniques. Experimental results demonstrate that our method is able to restore the camouflaged circuits with very little time consumption.

This paper presents a multilevel hypergraph partitioning method that balances constraints on not only the cell area but also the wire weight with a partition-based global placement algorithm that maximizes the wire density uniformity to control chemical-mechanical polishing (CMP) variations. The multilevel partitioning alternately uses two FM variants in the refinement stage to give a more uniform wire distribution. The global placement is based on a top-down recursive bisection framework. The partitioning algorithm is used in the bisectioning to impact the wire density uniformity. Tests show that, with a 10% constraint, the partitioning produces solutions with more balanced edge weights that are 837% better than from hMetis, 1039.1% better than MLPart, and 762.9% better than FM in terms of imbalance proportion and that this global placement algorithm improves ROOSTER with a more uniform wire distribution by 3.1% on average with an increased wire length of only 3.0%.

Divide-and-conquer methods for FPGA placement algorithms including partition-based and cluster-based algorithms have shown the importance of good quality-runtime trade-off. This paper describes a cluster-based FPGA placement algorithm targeted to a new commercial hierarchical FPGA device. The algorithm is based on a Markov clustering algorithm that defines a sequence of stochastic matrices operating on a generating matrix from the input FPGA circuit netlist. The core of the algorithm tightly couples a Markov clustering process with a multilevel placement process. Tests show its excellent adaptability to hierarchical FPGAs. The average wirelength results produced by the algorithm are 22.3% shorter than the results produced by the current hierarchical FPGA placer.

Hierarchical art was used to solve the mixed mode placement for three dimensional (3-D) integrated circuit design. The 3-D placement flow stream includes hierarchical clustering, hierarchical 3-D floorplanning, vertical via mapping, and recursive two dimensional (2-D) global/detailed placement phases. With state-of-the-art clustering and de-clustering phases, the design complexity was reduced to enhance the placement algorithm efficiency and capacity. The 3-D floorplanning phase solved the layer assignment problem and controlled the number of vertical vias. The vertical via mapping transformed the 3-D placement problem to a set of 2-D placement sub-problems, which not only simplifies the original 3-D placement problem, but also generates the vertical via assignment solution for the routing phase. The design optimizes both the wire length and the thermal load in the floorplan and placement phases to improve the performance and reliability of 3-D integrate circuits. Experiments on IBM benchmarks show that the total wire length is reduced from 15% to 35% relative to 2-D placement with two to four stacked layers, with the number of vertical vias minimized to satisfy a pre-defined upper bound constraint. The maximum temperature is reduced by 16% with two-stage optimization on four stacked layers.

Power is the major challenge threatening the progress of very large scale integration (VLSI) technology development. In ultra-deep submicron VLSI designs, clock network size must be minimized to reduce power consumption, power supply noise, and the number of clock buffers which are vulnerable to process variations. Traditional design methodologies usually let the clock router independently undertake the clock network minimization. Since clock routing is based on register locations, register placement actually strongly influences the clock network size. This paper describes a clock network design methodology that optimizes register placement. For a given cell placement result, incremental modifications are performed based on the clock skew specifications by moving registers toward preferred locations that may reduce the clock network size. At the same time, the side-effects to logic cell placement, such as signal net wirelength and critical path delay, are controlled. Test results on benchmark circuits show that the methodology can considerably reduce clock network size with limited impact on signal net wirelength and critical path delay.