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A self-assembled microbonded germanium/silicon heterojunction photodiode for 25 Gbps optical interconnects
No full text[[abstract]]A novel technique using surface tension to locally bond germanium (Ge) on silicon (Si) is presented for fabricating high performance Ge/Si photodiodes. Surface tension is a cohesive force among liquid molecules that tends to bring contiguous objects in contact to maintain a minimum surface energy. We take advantage of this phenomenon to fabricate a heterojunction optoelectronic device where the lattice constants of joined semiconductors are different. A high-speed Ge/Si heterojunction waveguide photodiode is presented by microbonding a beam-shaped Ge, first grown by rapid-melt-growth (RMG) method, on top of a Si waveguide via surface tension. Excellent device performances such as an operating bandwidth of 17 GHz and a responsivity of 0.66 and 0.70 A/W at the reverse bias of −4 and −6 V, respectively, are demonstrated. This technique can be simply implemented via modern complementary metal-oxide-semiconductor (CMOS) fabrication technologies for integrating Ge on Si devices.[[fileno]]2030192010012[[department]]電機工程學
Self-Aligned Microbonding Germanium Metal-Semiconductor-Metal Photodetectors Butt-Coupled to Silicon Waveguides
No full text[[abstract]]We present a butt-coupled Germanium (Ge) metal–semiconductor–metal photodetectors on silicon (Si) waveguides. This device is implemented by a novel process using self-aligned microbonding technique and rapid-melt-growth method for mono-lithically integrating single-crystal Ge and Si devices on the same plane. Through inserting a thin amorphous Si (a-Si) layer between the Ge and metal contact, the Schottky barrier height is modu-lated, which effectively reduces the dark current and increases the operation speed. The fabricated device shows a low dark current of 0.24 μ A, a 3 dB bandwidth of 15 GHz and a responsivity of 0.25 A/W, at a bias voltage of −2.6 V for wavelength 1310 nm.[[fileno]]2030192010013[[department]]電機工程學
Automatic single-frame-based rain streak removal via image decomposition
No full text[[abstract]]Rain removal from a video is a challenging problem and has been recently investigated extensively. Nevertheless, the problem of rain removal from a single image was rarely studied in the literature, where no temporal information among successive images can be exploited, making the problem very challenging. In this paper, we propose a single-image-based rain removal framework via properly formulating rain removal as an image decomposition problem based on morphological component analysis. Instead of directly applying a conventional image decomposition technique, the proposed method first decomposes an image into the low- and high-frequency (HF) parts using a bilateral filter. The HF part is then decomposed into a "rain component" and a "nonrain component" by performing dictionary learning and sparse coding. As a result, the rain component can be successfully removed from the image while preserving most original image details. Experimental results demonstrate the efficacy of the proposed algorithm.[[fileno]]2030144010024[[department]]電機工程學
Synthesis and Measurement of Sub-femtosecond Subcycle Periodic Pulses
No full text[[fileno]]2030165030079[[department]]電機工程學
Nondata- aided timing synchronization for cooperative MIMO OFDM systems
No full text[[abstract]]In cooperative multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems, signals transmitted from cooperating terminals arrive at the receiver on distinct timing due to diverse propagation delays. Therefore, timing synchronization is even more challenging in cooperative MIMO systems than in centralized MIMO configurations. Up to the present, various training sequence designs, along with synchronization algorithms, have been proposed. Among these data-aided approaches, a timing synchronization scheme utilizing unequal period synchronization patterns (UPSPs) was proposed. In this paper, from a non-data-aided perspective, we propose a generalized interleaved carrier assignment scheme that makes the resultant random OFDM data symbols themselves become UPSP-like, and develop a blind timing synchronization scheme accordingly. Simulation results show that the proposed non-data-aided approach with majority vote refinement (MVR) can achieve better performance than the original UPSP-based approach.[[fileno]]2030102030149[[department]]電機工程學
A compact preamble design for synchronization in distributed MIMO OFDM systems
No full text[[abstract]]In distributed multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems, signals arrive at the receiver on different timing and are characterized by distinct carrier frequency offsets (CFOs), which makes synchronization rather challenging than that associated with centralized MIMO systems. Current solutions to this problem are mainly based on special preamble designs, where different training sequences are cascaded and then separately used to assist timing synchronization and CFO estimation. Such preamble designs not only increase system overhead but also burden the receivers with independent algorithms for timing synchronization and CFO estimation. In this paper, we propose a low-overhead (compact) preamble having the same length as one OFDM symbol, along with a unified algorithm for both timing synchronization and CFO estimation. Furthermore, the CFO estimation range can be flexibly extended to cope with larger CFOs in the proposed approach. Under the same training overhead and power consumption, simulation results indicate that the proposed approach outperforms a timing synchronization scheme that based on unequal period synchronization patterns.[[fileno]]2030102030158[[department]]電機工程學
Impacts on the transmission grid for integrations of renewable energy in Taiwan
No full text[[abstract]]Due to the increasing recognitions in renewable energy worldwidely, the development of renewable energy has also become major alternative energy resources in Taiwan. This paper presents impact studies on the transmission grid for integrations of renewable energy in Taiwan. First, Taiwan's renewable energy policy will be briefly reviewed. Recent developments about integrations of renewable energy in the transmission grid will be presented. Finally, discussions about impacts on the transmission grid and suggested approaches are concluded.[[fileno]]2030140030046[[department]]電機工程學
Risk-based generator rejection protection system design in Taiwan Power System
No full text[[abstract]]In order to perform a rapid corrective action, prevent wide-area disturbances, and enhance power system reliability, there is a trend to design and implement inexpensive special protection systems (SPS) in recent years. However, excessive reliance on SPS can result in increased risk. In this paper, the generator rejection schemes (GRS), one of the simplest SPS, will be investigated for Taiwan Power System. Markov modelbased GRS will be studied for reliability assessments of SPS. Two GRS schemes will be analyzed for comparative studies: (1) one out of one rejection for one generator mechanism, and (2) two out of three rejections for one generator mechanism. Transient stability assessments are investigated by using DSATools. From our studies, the following statements can be concluded: (1) The reliability of two out of three rejections for one generator mechanism is better than that of one out of one rejection for one generator mechanism. (2) The power plant without generator rejection mechanism is more risky than the power plant with generator rejection mechanism when power output exceeds a threshold loading. (3) The critical clearing time indeed can be improved if GRS are applied for emergency control.[[fileno]]2030140030049[[department]]電機工程學
A Scalable Direct- Sampling Broadband Radar Receiver Supporting Simultaneous Digital Multibeam Array in 65nm CMOS
No full text[[abstract]]Intelligent environments significantly impact human daily lives through embedded sensing and actuating systems. Wireless sensors that can provide non-contact radio information are indispensable. Impulse radar is positioned as a favorable candidate in monitoring and sensing objects [1-3]. The impulse radio is inherently multipath immune and suitable for precision ranging. Accurately detecting signals with low power impulse radios imposes design challenges to impulse radar receivers. In this work, a direct-sampling receiver is proposed and implemented for an impulse radar system. It can support GHz instantaneous bandwidth and more than 100GS/sec equivalent sampling rate through the high-speed sampling circuits and on-chip timing circuitry. The wide bandwidth scattering time-domain waveforms in the radio interaction between the object and radar can be sampled and digitized by the receiver. It achieves precise measurement of time of arrival (TOA) in a radar system and expands the scalability towards antenna arrays for detection of direction of arrival (DOA) [4].[[fileno]]2030122030044[[department]]電機工程學
Leakage Energy Recovered Narrow Pulsed Voltage Generator Associated with Ultrasound Generator for Liquid Food Sterilization
No full text[[abstract]]This paper presents a narrow pulsed voltage generator along with an ultrasound generator for liquid food sterilization. The generator is derived from a bidirectional flyback converter with leakage energy recovery circuits, which can improve efficiency about 12%. In addition, the proposed generator is associated with a half-bridge inverter for generating ultrasound to clean sterilizer electrodes. In this combined generator, the switches in the converter and the inverter are integrated with the synchronous switch technique, reducing its weight, size and volume while improving efficiency significantly. Experimental results obtained from a prototype with the output voltage of +/- 6 kV similar to +/- 20 kV and peak power of 1.2 MW have verified its feasibility.[[fileno]]2030197030050[[department]]電機工程學