• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.486-493
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• 2010

This article introduces a novel ultra wideband(UWB) bandpass filter(BPF) with sharp roll-off characteristics in stripline structure. The UWB characteristic is basically obtained from capacitive coupled cross resonator. The resonator has ${\lambda}/2$ length. And at the center of the resonator, two stubs are loaded, one is a ${\lambda}/8$ short-circuited stub and the other is a ${\lambda}/8$ open-circuited stub. The two stubs provide two attenuation poles at lower and upper cutoff frequencies. For input and output lines, two identical capacitively coupled lines have been installed to suppress the unwanted signals in the lower and upper stopbands. The filter has been designed for the U.S. UWB band(3.1~10.6 GHz) with two transmission zeros at 2.4 and 11.1 GHz. The filter has been realized with Low Temperature Core-fired Ceramic(LTCC) green tape which has the dielectric constant of 7.8. Measurement results agree well with HFSS simulation results. Insertion loss less than 0.7 dB and return loss better than 14 dB in the pass band have been measured. The group delay in the center frequency is 0.27 ns and the group delay variation within pass band is less than 0.5 ns. The size of the filter is $6{\times}18{\times}0.6\;mm^3$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.49-60
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• 2017

In this paper, we presented the result of the study on high-power handling capability of the X-band circular waveguide cavity filter configured at the output of high power amplifier(120 W) for geostationary satellites. The dual mode circular waveguide cavity filter with 6th order is selected and the physical model of the filter is designed after determination of the size of resonator from mode chart. Multipactor margin analysis is performed by the SEM method and the VMF method. The result shows that the VMF method predicts lower multipactor breakdown thresholds than the SEM method. Evaluating the multipactor margin obtained by the VMF method to ECSS criteria, we could decide to perform multipactor test. The multipactor test conducted in ESA facility shows that multipactor did not occur even until the RF power increased up to 540 W. In consequence, by both analysis and test, we could verify that the X-band circular waveguide cavity filter has the sufficient high-power handling capability to operate on orbit.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.171-191
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• 2005

This Technical Memo(TM) was written for the purpose of determining the type of UHF-band power divider which is applicable to KSLV-1. For this, some different kinds of power divider are compared with there types and characteristics. And then, we select three types of power divider(which is Wilkinson power divider, Quadrature hybrid divider and Ring hybrid divider) and perform Schematic and Momentum simulation for finding the optimized characteristics. With this results, in order to demonstrate the selected power divider, we manufactured UHF-band power dividers using FR-4 epoxy plate. By the measured results, we obtain the similar results compare with simulation and fabrication. And Quadrature hybrid power divider is suitable to application to KSLV-1.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.3 s.357
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• pp.26-34
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• 2007

This Paper describes a chip design technique for body composition analyzer based on the BIA (Bioelectrical Impedance Analysis) method. All the functions of signal forcing circuits to the body, signal detecting circuits from the body, Micom, SRAM and EEPROMS are integrated in one chip. Especially, multi-frequency detecting method can be applied with selective band pass filter (BPF), which is designed in weak inversion region for low power consumption. In addition new full wave rectifier (FWR) is also proposed with differential difference amplifier (DDA) for high performance (small die area low power consumption, rail-to-rail output swing). The prototype chip is implemented with 0.35um CMOS technology and shows the power dissipation of 6 mW at the supply voltage of 3.3V. The die area of prototype chip is $5mm\times5mm$.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.52-60
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• 1999

Fabricability of phase shifted grating filters has been theoretically studied by an effective index transfer matrix method. In the optical band-pass filter with multiple ${\lambda}/4$ phase-shifts, the phase-shift error and random variation of the grating period should be suppressed such that corresponding resonance frequency lies within, the filter pass-band. The tolerance for the relative error is less than $10^3$, and is quite stringent in typical filters for WDM application. End facet reflection produces ripple in the transmission spectra and the reflectivity should be less than 1% in order to keep the ripple less than 0.25dB. Also, the effect of waveguide absorption loss is enhanced by the resonance in the filter, and the absorption should be limited to 1dB/cm for the signal loss of less than 0.2dB.

• Journal of Broadcast Engineering
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• v.4 no.2
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• pp.144-154
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• 1999

The binomial sequences are family of orthogonal sequences that can be generated with remarkable simplicity-no multiplications are necessary. This paper introduces a class of non-recursive multidimensional filters for frequency-selective image processing without multiplication operations. The magnitude responses are narrow-band. approximately gaussian-shaped with center frequencies which can be positioned to yield low-pass. band-pass. or high-pass filtering. Algorithms for the efficient implementation of these filters in software or in hardware are described. Also. we show that the binomial QMFs are the maximally flat magnitude square Perfect Reconstruction paraunitary filters with good compression capability and these are shown to be wavelet filters as well. In wavelet transform the original image is decomposed at different scales using a pyramidal algorithm architecture. The decomposition is along the vertical and horizontal direction and maintains constant the number of pixels required to describe the images. An efficient perfect reconstruction binomial QMF-Wavelet signal decomposition structure is proposed. The technique provides a set of filter solutions with very good amplitude responses and band split. The proposed binomial QMF-filter structure is efficient, simple to implement on VLSl. and suitable for multi-resolution signal decomposition and coding applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.981-984
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• 2005

Recently, filtering methods for attenuating noise while preserving image details are in progress actively. And SM(standard median) fille. showed a great performance for noise removal in impulse noise environment but, it caused edge cancellation error So, variable methods that modified SM(standard median)filter have been proposed, and CWM(center weighted median) filter is representative. Also, there are several methods to improve the efficiency based on min/max operation in term of preserving detail and filtering speed. In this paper, we managed a pixel corrupted by impulsive noise using min/max value of the surrounding band enclosing a pixel, and compared the efficiency with exiting methods in the simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.245-249
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• 2004

In this paper, we have proposed a clock recovery algorithm of Orthogonal Frequency Division Multiplexing/Quadrature Phase Shift Keying Modulation-Digital Microwave Radio(OFDM/QPSK-DMR) system using Band Limited-Pulse Shaping Filter(BL-PSF) and compared the clock phase error variance of OFDM/QPSK-DMR system with that of single carrier DMR system. The OFDM/QPSK-DMR system using windowing method requires training sequence or Cyclic Prefix (CP) to synchronize the clock phase of received signal. But transmit efficient is increased in our proposed DMR system because of no using redundant data such as training sequence or CP. The proposed clock recovery algorithm is simply realized in the OFDM/QPSK-DMR system using BL-PSF. The simulation results confirm that the proposed clock recovery algorithm has the same clock phase error variance performance in a single carrier DR system under Additive White Gaussian Noise(AWGN) environment.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.39-44
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• 2021

In this paper, two types of BPF(Band Pass Filter) which are hair-pin and interdigital have been designed for millimeter-wave application using two types of material which are LCP(Liquid Crystal Polymer) and PTFE(Polytetrafluoroethylene) and also, their performances such as bandwidth, insertion loss, and in-band flatness are compared. The proposed BPF are designed as third-order filters, and their pass band is from 26.5 GHz to 27.3 GHz. Interdigital BPF using PTFE substrate has most wide -3 dB S21 bandwidth of 7.8 GHz and hair-pin BPF using LCP substrate has most narrow -3 dB S21 bandwidth among the proposed four BPF. For in-band insertion loss, hair-pin BPF using PTFE substrate achieves low insertion loss better than -0.667 dB, and hair-pin BPF using LCP substrate exhibits relatively high insertion loss among the proposed four BPF better than -0.937 dB. However, the maximum difference in insertion loss performance among the proposed four BPF is 0.27 dB, which is too small to negligible. For in-band flatness, interdigital BPF using PTFE substrate shows greatest performance of 0.017 dB, and hair-pin BPF using LCP substrate exhibits the lowest performance of 0.07 dB. There are tiny difference in in-band flatness performance of 0.053 dB. As a results, it is considered that the BPF using LCP substrate can derive the performances similar to that of the BPF using PTFE substrate in Millimeter-wave band.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.2
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• pp.93-100
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• 2008

In this paper, Low Noise Block down converter(LNB) is designed for a Ka-band satellite television receiver only(TVRO) using commercially available MMIC. Designed Low Noise Block down-converter is composed of three stage amplifiers involving input noise matched at first amplification stage, image reject band pass filter, frequency mixer and intermediate frequency amplification. Through LNB Module power budget to obtain gain and attenuation, Optimum LNB devices satisfying Ka-band LNB technical specification are selected. Experimental results of designed Ka-band LNB yields conversion gain of over $58{\pm}1dB$, noise figure of less than 1.5dB and phase noise of -94.6dBc @10KHz.