We have developed an optical phase-locked loop (OPLL) that can operate over 500km. The coherent transmitter is a 1.54µm 13C2H2 frequency-stabilized CW fiber ring laser with a frequency stability of 2.0 × 10-11 and a linewidth of 4kHz. To obtain wide band operation with a bandwidth of 1GHz, we fabricated a high-speed fiber laser as a local oscillator. By using these fiber lasers, the OPLL circuit successfully generated an intermediate frequency signal with a phase error variance of 7.9 × 10-3 rad.
This paper presents a pixel array position sensitive detector (PSD) with analog winner-take-all (WTA) blocks. The pixels are divided into M-number of sub-groups and a WTA is assigned to each sub-group. The winner pixel of entire pixels is obtained from the sum of the sub-group's winner addresses. Detailed noise analysis shows that there is an optimal number of sub-groups for improved noise immunity.
This paper presents a novel graph-based evolutionary optimization technique called Evolutionary Graph Generation(EGG), and its application to the transistor-level design of analog circuits. The evolution process of EGG can be accelerated by a simple operation, called “transmigration”, which is to import previously generated solutions for creating advanced solutions. In this paper, we demonstrate the potential of EGG with transmigration capability through an experimental synthesis of current mirror circuits.
This paper presents a novel design-for-testability technique to reliably detect stuck-open faults in CMOS complex gates. The modified design uses an additional pair of transistors to establish a constant saturation current IDDQ through the transistors under test. Variations in current level are monitored using a built-in current sensor to detect the presence of stuck-open faults. Circuit simulations verify that the proposed design is also resilient to time skews caused by unequal delays in circuit paths.
This paper presents an improved design of a radiation-hardened static random access memory (SRAM) cell. The memory cell is designed to be tolerant to transient single-event upsets by taking advantage of the fact that for the same area, the surface mobility of NMOS transistors is greater than that of PMOS transistors. The results show that the proposed design is able to withstand single-event upsets for temperatures between -55°C to 125°C when subjected to radiation intensities of 1014 rad(Si)/sec without affecting the write performance of the memory. The circuit is also robust when impinging high energy particle strikes at various angles of incidence.
We aim for detection and recognition of planar objects in natural outdoor scenes under varying illumination conditions. To achieve this, we propose Relative Color Polygons (RCPs) using component colors of objects for color matching. They can be defined on many color spaces, and it is found that a 2D color space (XY space) is the optimal color space for our relative color method compared with other color spaces. To evaluate the invariance to illumination changes for object recognition, experiments have been carried out using 500 outdoor scene images. By using the proposed model, the color matching rate of the input images with the standard one was 95%. This framework is potentially applicable to image retrieval, image segmentation, image recognition, and so on.
In this paper an analytical drain current model in subthreshold region is proposed and can be used for MOS or PD-SOI transistors. The model can describe output current dependency on the drain voltage accurately as well as including short channel effects. The proposed model needs only two fitting parameters to predict the current of a transistor with very good accuracy and simply can be used in simulators. To validate the model, it is compared with two short channel MOS transistors with different technologies by HSPICE simulations.
In this paper a novel reference frame data compression method for the H.264/AVC is proposed. Proposed method introduce a new function including the DAP (Differential of Adjacent Pixel) method and Huffman coding tool between the frame memory and the image coding engine. Simulation results show that this method could achieve not only a stable compression rate but also realize a lossless compression without additional distortion to the coding process. Furthermore, proposed method will not induce further delay during the memory access period. Proposed method is hardware-friendly and could be implemented by only about 7,000 gates.