Equivalent series resistance

About: Equivalent series resistance is a research topic. Over the lifetime, 5335 publications have been published within this topic receiving 83362 citations. The topic is also known as: ESR.

Impedance analysis of thickness-shear mode quartz crystal resonators in contact with linear viscoelastic media

Abstract: An electromechanical description of the impedance response of thickness-shear mode quartz crystal resonators in contact with linear viscoelastic media is presented. Explicit assignments for equivalent circuit parameters (resistances, inductances, and capacitances), are derived in terms of the properties of the resonant piezoid and damping fluid medium. The calculation shows that the effect of fluid elasticity is a reduction in both the equivalent resistance and inductance relative to a corresponding viscous bulk. The lower inductance is due to a reduced decay envelope for shear wave propagation into the liquid; in effect, a smaller mass of liquid is “dragged” by the crystal. The lower equivalent resistance is due to the combined effect of lower energy dissipation and enhanced recoverable energy storage within the mechanically active fluid layer near the crystal surface. Comparison of model predictions with published results on a variety of undamped, viscously damped, and viscoelastically damped crystals shows very good agreement.

Precision high-frequency capacitor formed on semiconductor substrate

Abstract: A precision high-frequency capacitor includes a dielectric layer formed on the front side surface of a semiconductor substrate and a first electrode on top of the dielectric layer. The semiconductor substrate is heavily doped and therefore has a low resistivity. A second electrode, insulated from the first electrode, is also formed over the front side surface. In one embodiment, the second electrode is connected by a metal-filled via to a layer of conductive material on the back side of the substrate. In alternative embodiments, the via is omitted and the second electrode is either in electrical contact with the substrate or is formed on top of the dielectric layer, yielding a pair of series-connected capacitors. ESD protection for the capacitor can be provided by a pair of oppositely-directed diodes formed in the substrate and connected in parallel with the capacitor. To increase the capacitance of the capacitor while maintaining a low effective series resistance, each of the electrodes may include a plurality of fingers, which are interdigitated with the fingers of the other electrode. The capacitor is preferably fabricated in a wafer-scale process concurrently with numerous other capacitors on the wafer, and the capacitors are then separated from each other by a conventional dicing technique.

On an AlGaInP-Based Light-Emitting Diode With an ITO Direct Ohmic Contact Structure

Abstract: An interesting AlGaInP multiple-quantum-well light-emitting diode (LED) with a direct ohmic contact structure, formed by an indium-tin-oxide (ITO) transparent film and AuBe diffused thin layer, is fabricated and studied. The direct ohmic contact structure is performed by the deposition of an AuBe diffused thin layer and the following activation process on the surface of a Mg-doped GaP window layer. Experimental results demonstrate that a dynamic resistance of 5.7 Omega and a forward voltage of 1.91 V, under an injection current of 20 mA, are obtained. In addition, the studied LED exhibits a higher external quantum efficiency of 9.7% and a larger maximum light-output power of 26.6 mW. The external quantum efficiency is increased by 26% under the injection current of 100 mA, as compared with the conventional LED without this structure. This is mainly attributed to the reduced series resistance resulted from the relatively uniform distribution of AuBe atoms near the GaP layer surface and the effective current spreading ability by the use of ITO film. Moreover, the life behavior of the studied LED, under a 20-mA operation condition, is comparable to the conventional LED without this structure.