• Journal of electromagnetic engineering and science
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• v.9 no.3
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• pp.164-173
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• 2009

In this paper, two new circuit structures for European and U.S. ultra-wide band(UWB) bandpass filters(BPFs) with sharp roll-off characteristics are introduced. We show first that the ultra-wide bandpass property is obtained from a $\lambda$/4 open T resonator with a capacitively coupled $\lambda$/4 short-circuited line, which provides two attenuation poles at lower and upper cutoff frequencies. Then, two identical capacitively coupled input/output lines, which can be $\lambda$/4-length open ends or $\lambda$/2-length short ends, with the T-resonator, are adopted to suppress lower and higher frequency components outside of the pass band. There is coupling between the input and output lines providing two additional transmission zeros in the lower and upper transition bands of the filter. Since the coupling between the T-resonator with the $\lambda$/4 short-circuited line and the input/output lines limits the bandwidth of the filter to the European UWB band, both the $\lambda$/4 short-circuited line and the input/output lines are inserted between the two stacked T-resonators for the U.S. UWB band. The filter structures are simulated with ADS and HFSS and realized with low-temperature co-fired ceramic(LTCC) green tape which has the dielectric constant of 7.8. Measurement results agree well with HFSS simulation results.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.55-60
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• 2001

We propose a method to extract features optically from the input pattern by use of an array of Hough transfOllli filters. Here the subparts of the input pattern are Hough-transformed by. their cOlTesponding elements of the filter array independently and simultaneously. Compared with the conventional method, in which the whole input pattern is Hough-transformed by a single optical filter, the proposed method not only provides the improved optical transform results when the input pattern becomes complex but also extracts the approximate position information of the line segment features. To show the feasibility of this approach, we fabricated a $5\times5$ filter array and performed preliminary experiments.iments.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.149-156
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• 2012

A digital input class-D audio amplifier is presented for digital hearing aid. The class-D audio amplifier is composed of digital and analog circuits. The analog circuit converts a digital input to a analog audio signal (DAC) with noise suppression in the audio band. An interpolated digital delta-sigma modulator is used to convert data types between digital signal processor (DSP) and digital-to-analog converter (DAC). An 16-bit, 25-kbps pulse code modulated (PCM) input is interpolated to 16-bit, 50-kbps by a digital filter. The output signal of interpolation filter is noise-shaped by a third-order digital sigma-delta modulator (SDM). As a result, 1.5-bit, 3.2-Mbps signal is applied to simple digital to analog converter.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.833-839
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• 1986

This paper describes the development of a new type of an integrated optical filter using the frequency characteristics of a directly-connected directional coupler with a Rib waveguide. It has been designed for multiplexing and demultiplexing light froups in different wavelength regions. Also, the effects of higher modes, couplings between input waveguides or output waveguides, and dispersion of material are considered.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1125-1130
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• 2014

In this paper, we discuss the relation between the motion profile and pre-filter. As previously reported in various literatures [1-3], a tuned motion profile can effectively reduce residual vibration by placing inherent zeros of the motion profile at the vibratory pole of systems similar to the role of the input shaping technique. From the results, we factorize the motion profile into a basis function and an input shaper. In contrast to the previously reported impulse-sequence-based input shapers, the input shaper extracted from the motion profile has unique characteristics. Thanks to the characteristics of the input shaper extracted from the motion profile, it has advantages to reduce the vibrations caused by not only the modeled vibratory mode but also unmodeled dynamics which exist in higher frequency ranges.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.671-674
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• 1999

In the PWM converter, PLL(Phase Locked Loop) is usually used as a tool which senses the angle of input voltage. This is sensitive to nois and needs additional hardware. In this work, we propose a sensorless control scheme of PWM converter using EKF(Extended Kalman Filter). EKF estimates a phase angle of input voltage from nonlinear state equation using measured phase currents. We control power factor and DC-link voltage utilizing the estimated phase angle. We demonstrate the effectiveness of the proposed estimation algorithm through simulations.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.258-263
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• 1998

A comparative study of single-phase PWM converters having active filtering functions both on ac-input and dc-output sides have been carried out. Based on the function of the dc-output side active filter, two types of configurations, the RPM (ripple power managing) type and the APM (average power managing) type are compared to show their contrastive characteristics. The prototype system using DSP based control algorithms, i.e. deadbeet current control and voltage sensor-less technique using full-order observer, show the availability of the proposed system.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.243-246
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• 1997

In this paper, soft switching high power factor buck converter is proposed. This converter is composed of diode rectifier, a input capacitor can be small enough to filter input capacitor can be small enough to filter input current, buck converter with loss less snubber circuit. Converter is operated in discontinous conduction mode, turn of of the switching device is a zero current switching(ZCS) and high power factor input is obtained. In addition, zero voltage switching(ZVS) at turn of is achieved and switching loss is reduced using loss less snubber circuit. The capacitor used in the snubber circuit raised output voltage. Therefore, proposed converter has higher output voltage and higher efficiency than conventional buck type converter at same duty factor in discontious conduction mode operation.

• ETRI Journal
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• v.29 no.4
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• pp.470-476
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• 2007

In this paper, a versatile three-input five-output universal capacitor-grounded voltage-mode filter is proposed. The circuit employs two differential voltage current conveyors as active elements together with two grounded capacitors and four resistors as passive elements. The proposed configuration can be used as either a single-input five-output or three-input two-output. Unlike the previously reported works, it can simultaneously realize five different generic filtering signals: lowpass, bandpass, highpass, bandreject, and allpass. It still maintains the following advantages: (i) the employment of all grounded capacitors, (ii) no need to employ inverting-type input signals, (iii) no need to impose component choice, (iv) orthogonal control of the resonance angular frequency ${\omega}_o$ and the quality factor Q, and (v) low active and passive sensitivity performances.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.2004-2007
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• 2002

In the linear combination type stereophonic echo canceller, it is known not to converge the coefficient vector of the adaptive filter to a correct echo path. In this report, we analyze the convergence value of the filter coefficient vector of the stereo echo canceling algorithm using input signals of all channels in relation to this problem. In this analysis, one of the two inputs to the un-known system and adaptive one are assumed to be a delayed and attenuated version of the other signal as a model of the input signal with a strong cross-correlation. As a result, it is shown for the coefficient vectors not to converge to echo paths, and nor to converge to the value which depends on the time delay and the attenuation of the input signal. We show that the computer simulation result are corresponding to our analytical results.