High Rate Data Synchronization in GALS SoCs

Globally asynchronous, locally synchronous (GALS) systems-on-chip (SoCs) may be prone to synchronization failures if the delay of their locally-generated clock tree is not considered. This paper presents an in-depth analysis of the problem and proposes a novel solution. The problem is analyzed considering the magnitude of clock tree delays, the cycle times of the GALS module, and the complexity of the asynchronous interface controllers using a timed signal transition graph (STG) approach. In some cases, the problem can be solved by extracting all the delays and verifying whether the system is susceptible to metastability. In other cases, when high data bandwidth is not required, matched-delay asynchronous ports may be employed. A novel architecture for synchronizing inter-modular communications in GALS, based on locally delayed latching (LDL), is described. LDL synchronization does not require pausable clocking, is insensitive to clock tree delays, and supports high data rates. It replaces complex global timing constraints with simpler localized ones. Three different LDL ports are presented. The risk of metastability in the synchronizer is analyzed in a technology-independent manner     

Self-oscillating dimmable electronic ballast

This paper presents a simple alternative for an electronic ballast operating in self-sustained oscillating mode with dimming capability for fluorescent lamps. A simple modification in one of the gate drivers side circuit allows the lamp to dim without compromising the simplicity, reliability, and low cost which characterize the self-oscillating electronic ballast (SOEB). A qualitative analysis is presented to explain the behavior of the proposed self-oscillating electronic ballast with dimming feature. In addition, the stability and the key equations for the design are derived using the extended Nyquist criterion and describing function method. Experimental results from two 40-W electronic ballasts are presented to demonstrate the performance and to validate the analysis carried out.     

Ambient Technology — Now You See It, Now You Don't

The continuing progression of Moore's Law has enabled the miniaturisation and dramatic cost reduction in electronics over the last ten years. For a truly pervasive communications environment the challenges of hiding key hardware technologies from the user are rapidly being overcome. This paper reviews the status of these hardware technology developments in the pervasive space and briefly discusses other contributing factors that will enable the pervasive vision to be realised.     

Smooth profile generation for a tile printing machine

In this paper a digital filter is proposed for the generation of smooth set points for motion control systems. The proposed nonlinear filter produces profiles with bounded velocity and acceleration starting from rough reference signals (steps and ramps). An actual implementation of the filter for a tile printing machine is presented and experimental results are reported.     

Intergranular corrosion of a light aircraft aluminum alloy propeller

Examination of the wreckage of a light aircraft revealed that approximately 20 cm was missing from one tip of the aluminum alloy propeller. Fractographic and metallographic examination of the remaining portion of the propeller revealed extensive grain-boundary separation in the vicinity of the fracture, and grain edges and corners rounded by corrosion on the fracture surface. Energy dispersive X-ray analysis (EDXA) revealed fluorine on, and in the vicinity of, the fracture surface. In the ensuing litigation, it was asserted that the crash occurred because the propeller fractured in flight as the result of intergranular attack caused by the use of a fluorine-bearing cleaner.     

RF microelectronics for W-CDMA mobile communication systems

Third generation (3G) mobile communication systems are now just starting to be introduced. With a maximum data rate of 2 Mbit/s they will make wireless access to broadband data services like the Internet or video applications feasible. Most of the different physical layer technologies summarised under the acronym 3G are based on wideband-CDMA (W-CDMA), in contrast to existing second generation systems, which mostly use TDMA and FDMA. This has severe consequences for the design of the transceiver front-ends. During standardisation these were assumed to have an adequate RF performance yet they still present a performance bottleneck for the system. Starting with a short introduction to UMTS (Universal Mobile Telecommunications System)-the 3G standard to be deployed in Europe and already operating in Japan-this paper describes by way of example some of the test cases specified for UMTS and their impact on the analogue front-end. It is shown that accurate simulation of all the analogue and digital signal processing is necessary in order to predict the RF performance needed of today's commercial RFICs. The paper then presents and reviews some actual design examples. Finally, possible technologies and techniques for application in future mobile terminals are discussed     

Crosstalk between microstrip transmission lines

Methods for prediction of crosstalk between microstrip transmission lines are reviewed and simplified for the weak-coupling case. Classical coupled transmission line theory is used for uniform lines, and potential and induced EMF methods are used for crosstalk between nonuniform lines. It is shown that the potential method is equivalent to classical coupled transmission line theory for the case of uniform lines. An experiment was performed for uniform coupled microstrip lines for frequencies from 50 MHz to 5 GHz, and good agreement between theory and measurement was obtained for both near- and far-end crosstalk