The importance of testing complex electronics
The increasing functionality of modern electronics systems is being achieved through more complex integrated circuits, dense surface mount assemblies and increasingly through the use of multiple complex ICs interconnected to form multi-chip modules, all of which have progressively increased the cost of testing and its share of production cost, so that test costs are dominant today. Initiatives taken in Europe by leading corporations and recently adopted as IEEE standards for logic circuit testability, are now enabling electronic access for in-circuit testing and diagnostics at IC and board and MCM level, thereby improving quality and throughput in the manufacture of electronics. various proprietary solutions are also being introduced very effectively for analogue circuits, and for specialised computing and telecommunications systems, some using expert systems to aid diagnostics and improving the quality and throughput of testing. The solutions are most cost-effectively introduced at the design stage when maximum impact can be achieved on subsequent life-cycle costs.
VHDL links design, test, and maintenance
The authors discuss the very high-speed integrated circuit (VHSIC) hardware description language (VHDL), a universal HDL that is being adopted for design tools throughout the electronics industry in the wake of its December 1987 approval as IEEE Standard 1076-1987. The main purpose of VHDL is to allow designers to model, synthesize, and simulate components, chips, and systems from the most abstract behavioral level through logic gates. The authors briefly consider some existing HDLs, examine some VHDL tools that are now in use in industry and at universities, describe the benefits of VHDL, and relate the experiences of some users.<<ETX>>
Refinement of crystal structure parameters using convergent‐beam electron diffraction: the low‐temperature phase of SrTiO3
The method to refine crystal structure parameters (atom positions and Debye–Waller factors) using convergent-beam electron diffraction (CBED), which is applicable to crystal structure analysis of a small specimen area down to a few nm in diameter, is studied. The line profiles of higher-order Laue-zone reflections are recorded using imaging plates. Theoretical intensities are calculated based on the dynamical theory of electron diffraction with the aid of the generalized Bethe approximation to shorten calculation time. The structural parameters are determined by fitting the experimental profiles with the theoretical ones using a nonlinear least-squares method. The present method has been applied to the low-temperature phase of SrTiO3. The structural parameter or the rotation angle of the oxygen octahedron has been determined to be \varphi = 1.12 (4)°, which shows good agreement with that obtained from electron spin resonance experiments.