Applied Mechanics and Materials Vols. 284-287

Abstract: Power electronic converters produce not only characteristic harmonics, but also both non-characteristic harmonics and interharmonics. This paper presents the physical background of both non-characteristic harmonics and interharmonics. Generation causes are explored and discussed in detail. Extensive series of simulation of different power converter topologies are provided and compared with experimental results and existing standards. This research offers missing background for standards covering low-frequency EMC.

Abstract: In this paper the process of implementing a low dropout regulator (LDO) chip is presented; it is using uses Taiwan Semiconductor TSMC’s Manufacture Inc. 0.35um 2P4M process. The circuit designed with the described process can be is operated at 3-5V input voltage to generate 2.5V output voltage. Maximum output current can be running up to 200mA. This LDO is implemented without placing output capacitors to reduce BOM (Bill of Material) cost and stable between 0~200mA loading current and the chip is stable when the loading current is in the range 0~200mA. [8] The new proposed LDO chip can be implemented in the handheld mobile devices, battery powered equipment, wireless devices, cordless phones, or PC peripherals.

Abstract: This paper presents a low-power fast-settling low-dropout regulator (LDO) using a digitally assisted voltage accelerator. Using the selectable-voltage control technique and digitally assisted voltage accelerator significantly improves the transition response time within output voltage switched. The proposed LDO regulator uses the selectable-voltage control technique to provide two selectable-voltage outputs of 2.5 V and 1.8 V. Using the digitally assisted voltage accelerator when the output voltage is switched reduces the settling time. The simulation results show that the settling time of the proposed LDO regulator is significantly reduced from 4.2 ms to 15.5 μs. Moreover, the selectable-voltage control unit and the digitally assisted voltage accelerator of the proposed LDO regulator consume only 0.54 mW under a load current of 100 mA. Therefore, the proposed LDO regulator is suitable for low-power dynamic voltage and frequency-scaling applications.

Abstract: Modern electronic products require many high-speed differential pairs which require more layout space in PCB design. We propose a twisted-overlap differential-pair (TODP) structure to obtain more routing space and achieve better signal integrity in this study. TODP reduces the layout space requirement by about 25% compared with that required by traditional differential pairs and the twisted differential lines (TDL) structure [2]. Based on an eye diagram performance the TODP design compared to the traditional and TDL designs can improve the peak-to-peak jitter by 26.5% and 12.2%, the overshoot by 14.3% and 2%, the undershoot by 18.8% and 5%, and the eye width by 2 and 1%, respectively. Our results indicate that TODP may be of great benefit in differential-pair PCB design.

Abstract: This paper proposes a high-efficiency dimmable LED driver for light emitting diodes (LED). The developed LED driver consists of a full-bridge resonant converter and six buck converters. The function of the full-bridge resonant converter is to obtain a smooth dc-link voltage for the buck converters by phase-shift modulation (PSM) while that of the six buck converters is to drive six LED modules, respectively. The gate voltage of the active switch of each buck converter is a combination of high-frequency and low-frequency pulses. The duty ratio of the high-frequency pulse controls the LED voltage and thereby, controls the amplitude of LED current. LEDs are dimmed by low-frequency pulse-width modulation (PWM) to vary the average current flowing through LED. Circuit equations are derived and circuit parameters are designed. High circuit efficiency is ensured by operating the active switches at zero-voltage switching-on to reduce the switching loss. Finally, a prototype circuit was built to verify the accuracy and feasibility of the proposed LED driver.

Abstract: In this paper, different silicon oxide-based films and electrode materials were deposited onto the W/Si substrates by sputtering to investigate the resistive switching characteristics of the conductive-bridging RAM cells via the ion migration. A room-temperature constant-voltage stressing has been used to examine its effects on the resistive switching behaviors of the RAM cells in this work. Our experimental results show that the constant-voltage stressing can effectively affect the current conduction behavior and stabilize the resistive switching of the memory cell. After the electrical stressing, the current conduction mechanism in the HRS during the set process of the Cu/Cu:SiO₂/W cell can be changed from the Ohm’s law and the space charge limited conduction to the single Ohm’s law.

Abstract: This paper presents an interleaved boost converter with boost-type snubber for PV system. Paralleled converters working in interleaving manner are adopted to eliminate the pulsating current and increase powering capacity. Boost-type snubber is utilized for soft-switching of the power transistor to reduce switching losses. By switch integration, one boost-type snubber can be shared by N phases of boost converter to effectively reduce component counts and costs. The improved supply characteristics and conversion efficiency make it suitable for charging applications. A prototype for battery charger has been implemented to prove the feasibility of the proposed topology.

Abstract: This paper presents a Reflex charger realized by N sets of interleaved soft-switching converters with L-C-D snubbers. The interleaved converters used for implementing the Reflex charging technique can be interleaved boost, interleaved buck-boost, and interleaved sepic converters. The use of the L-C-D snubber in each set of interleaved converter is to reduce turn-off switching losses, hence, to achieve higher conversion efficiencies of the interleaved converters and to extend the lifetime of rechargeable batteries. A prototype of Reflex charger with four sets of interleaved buck-boost con-verters is implemented for charging lead acid batteries of 12V. Experimental results show that the proposed circuit structure can generate the required positive/negative pulses for the Reflex charging.

Abstract: With the advent of digital convergence trends, the current smartphone equipped with more powerful hardware and complex software to satisfy the increased user requirements. Additionally, similar to video game console, the pioneers of smartphone manufacturers consider adopting the motion recognition to extend their functionality. In this paper, we modify a commodity smartphone system to recognize the motion of users using an on-board camera and the OpenCV library. Additionally, we also implement a performance monitoring system which consists of a kernel monitoring module and a user-level logger. Based on the system, we analyze the performance impact and bottleneck of motion recognition with representative smartphone workloads, and propose the points for improvement in term of system architecture.

Abstract: In this paper, intrinsic nanocrystalline silicon thin films were deposited onto the ITO/glass substrates by PECVD and were used as the conduction material for the conductive-bridging random-access memory devices. The resistive switching characteristics of the nanocrystalline silicon thin films were investigated. Experimental results have shown that the stable bipolar resistive switching of the nc-Si films and retention time over 10⁴s. In addition, the current conduction mechanism of the nanocrystalline silicon films was examined with XPS depth file analysis. It clearly indicates that the conduction mechanism for the resistive switching is formation metallic bridges come form metal cation migration in the nanocrystalline silicon films.