One of a critical problem in the biomedical signals measurements is hum noise activity due to power line interference. Various approaches to suppress hum noise both analog and digital techniques have been proposed. However, these approaches have some disadvantages. N-path notch filter can be an alternative solution for this problem. The notch depth in a conventional N-path notch filter is limited by the number of paths to achieve deeper notch. This paper proposes a new N-path notch filter with additional sample-and-hold (S/H) and leak buffer circuits to improve notch depth. Simulation and measurement results of 3-phase N-path filter achieve notch depth of 61.6dB and 54.5dB respectively.

This paper presents the signal processing scheme realized in the early vision model of the retina, which was introduced to improve the measurement accuracy of a time to digital converter. Each oscillator output waveform of the ring coupled oscillators, inspired by the early vison model, is regarded as the photoreceptor cell output of the retina. The problems involved in utilizing the early vision model are explained and solutions are discussed. The proposed TDC performance is simulated by using SPECTRE simulation with the 0.18 μm 1-poly 4-metal CMOS process.

We propose a robust method for incrementally estimating a regular-grid ground surface map from stereo image sequences captured by nearly front-looking vehicle-mounted stereo cameras. The method simultaneously estimates a camera ego-motion and vertex heights of a regular mesh, which is composed of piecewise triangular patches drawn on a level plane in the ground coordinate system, by minimizing pixel value differences over the ground surface. The method combinationally uses feature-based approach and pixel-based approach for robustly estimating ego-motion parameters. We also show that this combination is beneficial for removing outlier pixels, which mainly represent the edge of the self-shadow area on the ground surface. The validity of the proposed method is demonstrated through experiments using real images.

This paper proposes a three-dimensional motion capture and feedback system for flying disc learners with use of Kinect device. Compared with conventional 3-D motion capture systems, Kinect has advantages of cost merit, easy system development and operation. The proposing system captures learners’ body movement, checks their skeleton positions in pre-motion/motion/post-motion in several aspects, and displays feedback messages to improve their motions. A novice learner of flying disc is trained to keep arm movement in steady height, to twist the waist, and to stretch the elbow according to the waist angle. A result of controlled experiment shows that the proposing system is effective for beginners to improve their movements.

Quadrature oscillators are effective in applications such as clock-recovery circuits and complex signal processing. In this paper, the oscillation frequency of the CMOS inverter-type N-stage ring oscillator with wired-OR connections is analyzed. The analysis is applied to a quadrature oscillator proposed in 2008, called the ORIGAMI oscillator, and the extended N-stage ring oscillators. To verify the oscillation frequency analysis, the formulated oscillation frequency is compared with simulated frequency using HSPICE assuming 0.18 μm CMOS processes.

A charge-based table lookup MOSFET capacitance model is derived for a circuit simulation application. Measured C/sub gs/(V/sub ds/, V/sub gs/) and C/sub gd/(V/sub ds/, V/sub gs/) tables and a calculated Q(V/sub ds/, V/sub gs/) table are utilized for representing nonlinear MOSFET capacitance behavior. The substrate terminal effect for C/sub gs/ and C/sub gd/ is expressed by using the plural sets of charge and capacitance tables, in which each set is defined at a specified substrate voltage. Not only the short-channel effect, but also the subthreshold capacitance characteristics, can be accurately modeled by the experimental data without any analytical approximations.

This paper describes a method for connecting an MOSFET 2-D device simulator to a circuit simulator via a 3-D table look-up MOSFET model. The computational cost of the device simulator is drastically reduced by a proposed monotonic piecewise cubic interpolation technique. With this technique, the device simulator needs to calculate only 100 ~ 200 points to make up an accurate 3-D table look-up MOSFET model. The computational time necessary for the interpolation is only about one third of the time for calculating one current point by the device simulator.