Testing two-phase transition signaling based self-timed circuits in a synthesis environment

Journal ArticleThe problem of testing self-timed circuits generated by an automatic synthesis system is studied. Two-phase transition signalling is assumed and the circuits are targetted for an asynchronous macromodule based implementation as in [?, ?, ?, ?]. The partitioning of the circuits into control blocks, function blocks, and predicate (conditional) blocks, originally conceived for synthesis purpose, is found to be very elegant and appropriate for test generation. The problem of data dependent control flow is solved by introducing a new macromodule called SCANSELECT (SELECT with scan). Algorithms for test generation are based on the Petri-net like representation of the physical circuit. The techniques are illustrated on the high-level synthesis system called SHILPA being developed by the Author's

A framework for hardware design analysis and synthesis using VHDL

technical reportAn approach for behavioral analysis and synthesis in a single framework is presented. The main advantage of specifying circuits at an abstract level is that they become amenable to formal analysis. A formalism HOP, which is an extended automaton model to describe behaviors of circuits is introduced. A set of static semantic checks called well-formedness checks is defined on the HOP automata to prevent common design errors in circuits synthesized from the behavior. An interconnection of behavioral descriptions, called a structural description, can be written and analyzed for well formedness. Algorithms for inferring an equivalent behavioral description from a given structural description have been developed. In order to avoid the creation of yet another HDL the HOP automaton has been embedded in a standard HDL, VHDL. Therefore, we have a formal semantic basis that is important in verification for the subset of VHDL denoted by HOP automata Standard VHDL based analysis and synthesis tools can be used. In addition, we have available a semantically correct way of inferring VHDL behavioral descriptions from VHDL structural descriptions. The inferred behavior in VHDL is useful in simulation, in simulation based verification and could be uscd in test generation tools. The above ideas have been implemented in the form of a C | | prototype, experiment have been performed with this prototype on a number of realistic designs, including the pipelined stack, pipelined cache memory system, AMD 2910 microprogram address sequencer and a switch level stack controller. The VHDL support comes from a commercial tool developed by Viewlogic Systems, Inc

27.5s 27.5 Implicit Enumeration of Structural Chang es in Circuit Optimization

We describe an implicit technique for enumerating structural choices in circuit optimization. The restructuring technique relies on the symbolic statements of functional decomposition which explores behavioral equivalence of circuit signals through rewiring and resubstitution. Using rigid, yet practical, formulation a rich variety of restructuring candidates is computed symbolically and applied incrementally to produce circuit changes with predictable structural effects. The restructuring technique is used to obtain much improved delays of the already optimized circuits along with their area savings. It is also applied to analyze benefits of optimizing circuit topology at the early steps of synthesis targeting its routability

THE ABILITY TO ESTIMATE POWER CONSUMPTION DURING EARLY-STAGE DEFINITION AND TRADE-OFF STUDIES IS A KEY NEW METHODOLOGY ENHANCEMENT. OPPORTUNITIES FOR SAVING POWER CAN BE EXPOSED VIA MICROARCHITECTURE-LEVEL MODELING, PARTICULARLY THROUGH CLOCK- GATING AND

emerged as a major constraint in the design of microprocessors. At the low end of the performance spectrum, namely in the world of handheld and portable devices or systems, power has always dominated over performance (execution time) as the primary design issue. Battery life and system cost constraints drive the design team to consider power over performance in such a scenario. Increasingly, however, power is also a key design issue in the workstation and server markets (see Gowan et al.) 1 In this high-end arena the increasing microarchitectural complexities, clock frequencies, and die sizes push the chiplevel—and hence the system-level—powe

A review of morphing aircraft

Aircraft wings are a compromise that allows the aircraft to fly at a range of flight conditions, but the performance at each condition is sub-optimal. The ability of a wing surface to change its geometry during flight has interested researchers and designers over the years as this reduces the design compromises required. Morphing is short for metamorphose: however, there is neither an exact definition nor an agreement between the researchers about the type or the extent of the geometrical changes necessary to qualify an aircraft for the title “shape morphing”. Geometrical parameters that can be affected by morphing solutions can be categorized into: planform alteration (span, sweep and chord), out-of-plane transformation (twist, dihedral/gull, spanwise bending) and airfoil adjustment (camber and thickness).Changing the wing shape or geometry is not new. Historically, morphing solutions always led to penalties in terms of cost, complexity or weight, although in certain circumstances these were overcome by system level benefits. The current trend for highly efficient and “green” aircraft makes such compromises less acceptable, calling for innovative morphing designs able to provide more benefits and fewer drawbacks. Recent developments in “smart” materials may overcome the limitations and enhance the benefits from existing design solutions. The challenge is to design a structure that is capable of withstanding the prescribed loads, but is also able to change its shape: ideally there should be no distinction between the structure and the actuation system. The blending of morphing and smart structures in an integrated approach requires multi-disciplinary thinking from the early development, which significantly increases the overall complexity, even at the preliminary design stage. Morphing is a promising enabling technology for future, next generation aircraft. However, manufacturers and end users are still too skeptical of the benefits to adopt morphing in the near future. Many developed concepts have a technology readiness level that is still very low. The recent explosive growth of satellite services means that UAVs are the technology of choice for many investigations on wing morphing.This paper presents a review of the state of the art on morphing aircraft and focuses on structural, shape changing morphing concepts for both fixed and rotary wings, with particular reference to active systems. Inflatable solutions have been not considered, and skin issues and challenges are not discussed in detail. Although many interesting concepts have been synthesized, few have progressed to wing tunnel testing, and even fewer have flown. Furthermore, any successful wing morphing system must overcome the weight penalty due to the additional actuation systems.<br/