R.D. Newbould

IP protection for VLSI designs via watermarking of routes

Intellectual property protection (IPP) has become a major concern in todays CAD and ASIC/SOC industries. This paper presents a watermarking technique for IPP at the physical design level. We propose a method for embedding a watermark by modifying the number of vias or bends used to route the nets in a design. This technique is applicable to digital, analog and mixed-signal design, and has the ability to accommodate the noise tolerance and design intricacies of each.

Isotropic diffusion weighting in radial fast spin-echo magnetic resonance imaging

Radial fast spin‐echo (radial‐FSE) methods enable multishot diffusion‐weighted MRI (DWMRI) to be carried out without significant artifacts due to motion and/or susceptibility and can be used to generate DWMRI images with high spatial resolution. In this work, a novel method that allows isotropic diffusion weighting to be obtained in a single radial k‐space data set is presented. This is accomplished by altering the direction of diffusion weighting gradients between groups of TR periods, which yield sets of radial lines that possess diffusion weighting sensitive to motion in different directions. By altering the diffusion weighting directions and controlling the view ordering appropriately within the sequence, an effectively isotropic diffusion‐weighted image can be obtained within one radial‐FSE scan. The order in which radial lines are acquired can also be controlled to yield data sets without significant artifacts due to motion, T2 decay, and/or diffusion anisotropy. Magn Reson Med 53:1347–1354, 2005.

A hierarchy of physical design watermarking schemes for intellectual property protection of IC designs

A method is presented for embedding the same watermark multiple times into a single integrated circuit design using a hierarchy of incorporation techniques. This has the advantage of adding multiple independent signatures to the circuit in order to better resist large-scale attacks. A high degree of robustness is provided by requiring attacks on multiple stages of the VLSI design flow in order to properly efface the mark.

Mixed signal design watermarking for IP protection

It has become apparent that a means of protecting physical design intellectual property (IP) is necessary in the global IP block commerce market. IP design is a costly enterprise, making block theft a lucrative trade. This work builds on previous analog watermarking research, extending the methodology into the mixed signal realm with a modification of the analog technique, and the addition of a compatible digital watermarking scheme. Results of analysis and testing on a small digital design-a priority decoder-is presented. The next step is integration of this technique into a full implementation of the automated mixed signal watermarking software.

Candidate generation for 45 degree routing for mixed-signal layout

This paper presents an efficient methodology for automatic 45-degree and 90-degree routing of mixed-signal layouts. Non-Manhattan geometries in routing have the advantage of lowering the bound on the shortest route between terminals as well as lowering the via count through use of metal bends. These non-Manhattan routed designs can be employed to reduce interconnection length, signal delay, circuit area, and power consumption over 90-degree routing. When combined with our previous and ongoing work in routing digital and analog circuits, the routing technique presented here will provide an improved mixed-signal routing environment. The algorithm described in this paper generates candidate routes with 45 and 135-degree segments for any two terminal net. Each candidate is guaranteed to be shorter or as short as the Manhattan distance between the terminals.

Placement watermarking of standard-cell designs

This paper presents two methods for embedding a watermark to protect intellectual property in a standard-cell layout. The information is added by inserting spaces between placed cells. Our proposed two methods allow the watermark to be added directly to the layout in the spatial domain, or added in the spectral domain using a frequency-domain transform.

Watermarking of standard-cell feedthroughs in mixed-signal design

This paper presents a method for watermarking standard-cell designs in a mixed-signal design environment. The method utilizes the constraints that are placed on a mixed-signal standard-cell design in terms of routing layers, utilizing feedthroughs to watermark the standard-cell portion of the design. The design is watermarked by modifying placement of feedthroughs in the design, allowing the designer flexibility in their placement.

Cluster growth revisited: fast, mixed-signal placement of blocks and gates

A method for placement of circuit elements using fast clustering is presented. The method uses bi-level cost functions and efficient storage structures to keep the search space reasonable, even with very large layouts. These cost functions allow for not just general path-delay minimization and aspect ratio maintenance, but also mixed signal and diagonalized routing criteria. Thermal profiling, noise thresholding, device matching, and bounding box ratios can all be constrained in the placement. This method expands and builds upon the classical cluster growth algorithm; the true advantage of this method lies in its ability to scale up to problems too large to be considered using traditional, heuristic algorithms, and without assumptions about layout styles.