Freescale Semiconductor

Abstract: A 4-Mb magnetoresistive random access memory (MRAM) with a novel magnetic bit cell and toggle switching mode is presented. The circuit was designed in a five level metal, 0.18-mum complementary metal-oxide-semiconductor process with a bit cell size of 1.55 mum2. The new bit cell uses a balanced synthetic antiferromagnetic free layer and a phased write pulse sequence to provide robust switching performance with immunity from half-select disturbs. This switching mode greatly improves the operational performance of the MRAM as compared to conventional MRAM. A detailed description of this 4-Mb toggle MRAM is presented

Abstract: Spin-transfer in nanometre-scale magnetic devices results from the torque on a ferromagnet owing to its interaction with a spin-polarized current and the electrons' spin angular momentum. Experiments have detected either a reversal or high-frequency (GHz) steady-state precession of the magnetization in giant magnetoresistance spin valves and magnetic tunnel junctions with current densities of more than 10(7) A cm(-2). Spin-transfer devices may enable high-density, low-power magnetic random access memory or direct-current-driven nanometre-sized microwave oscillators. Here we show that the magnetization oscillations induced by spin-transfer in two 80-nm-diameter giant-magnetoresistance point contacts in close proximity to each other can phase-lock into a single resonance over a frequency range from approximately 24 GHz for contact spacings of less than about approximately 200 nm. The output power from these contact pairs with small spacing is approximately twice the total power from more widely spaced (approximately 400 nm and greater) contact pairs that undergo separate resonances, indicating that the closely spaced pairs are phase-locked with zero phase shift. Phase-locking may enable control of large arrays of coupled spin-transfer devices with increased power output for microwave oscillator applications.

Abstract: Today9s electronic gadgets, such as digital cameras and mp3 players, often contain three different types of memory, because none of these memory types-static random access memory, dynamic random access memory, and Flash-can fulfill all memory requirements of these devices In his Perspective, A…kerman discusses magnetoresistive random access memory (MRAM), a promising candidate for a "universal memory" that combines all the strengths and none of the weaknesses of the existing memory types Several companies have succeeded in creating multi-megabyte MRAM prototypes, suggesting that large-scale introduction of MRAM devices to the market is not far off

Abstract: A dynamically rapid method used for tracking the maximum power point of photovoltaic arrays, known as ripple correlation control, is presented and verified against experiment The technique takes advantage of the signal ripple, which is automatically present in power converters The ripple is interpreted as a perturbation from which a gradient ascent optimization can be realized The technique converges asymptotically at maximum speed to the maximum power point without the benefit of any array parameters or measurements The technique has simple circuit implementations

Abstract: Sensors at separate locations measuring either the time difference of arrival (TDOA) or time of arrival (TOA) of the signal from an emitter can determine its position as the intersection of hyperbolae for TDOA and of circles for TOA. Because of measurement noise, the nonlinear localization equations become inconsistent; and the hyperbolae or circles no longer intersect at a single point. It is now necessary to find an emitter position estimate that minimizes its deviations from the true position. Methods that first linearize the equations and then perform gradient searches for the minimum suffer from initial condition sensitivity and convergence difficulty. Starting from the maximum likelihood (ML) function, this paper derives a closed-form approximate solution to the ML equations. When there are three sensors on a straight line, it also gives an exact ML estimate. Simulation experiments have demonstrated that these algorithms are near optimal, attaining the theoretical lower bound for different geometries, and are superior to two other closed form linear estimators.