Abstract: Class-D amplifier has been a popular device because it features very high power efficiency. However, with increasing power demand, the over-current/-voltage/-temperature protections of amplifiers are necessary to prevent over-heated damage caused by consuming large power consumption over a long time. This paper thus presents the method to dynamically reduce the total power loss of class-D amplifier according to the feedback signal of temperature sensor. The proposed scheme simultaneously reduces the static and dynamic power loss by lowering current delivery progressively and enabling parts of segmented power stages that are in need of conduction. The simulation results show that the total power loss (i.e. excessive heat) and relative temperature difference on chip packages can be reduced to 5.8% of the maximum value that is 12% improvement than that of conventional design. Moreover, the corresponding improvement on power efficiency is over 19% for the cases of small modulation indexes

• Publication Date: 14-Jul-2013
• DOI: 10.15224/978-981-07-7021-1-33
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Abstract: The signal enhancement using the evanescent electric field monitoring in the gold nanoparticles (AuNPs) filled surface plasmon resonance (SPR) biosensing is of interest here. The profiles of average evanescent electric fields in a direction normal to the gold/saline layer interface of the 2-dimensional (2D) system are generated at various surface AuNP densities. The shift of the corresponding power density profile increases consistently with the density. The SPR curves associated with dielectric effects from AuNPs are next determined. It shows that the SPR curve shift also possesses the similar characteristic to that of the evanescent field. The evanescent field approach may thus be a potential tool for analyzing SPR signal enhancement.

• Publication Date: 14-Jul-2013
• DOI: 10.15224/978-981-07-7021-1-36
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