• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.563-568
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• 2003

In this paper, a miniaturized parallel coupled bandpass filter using multi-layered LTCC(Low Temperature Co-fired Ceramics) substrate for SOP(System-On-Package) is proposed for applications to wireless communication systems. The fabricated BPF is composed of five 106${\mu}{\textrm}{m}$ thick LTCC layers and its size is 5.24mm x 4.3mm x 0.53 mm. The measured characteristics of the BPF show the center frequency of 5.8GHz, bandwidth of 200MHz, insertion loss of 2.326dB and return loss of 13.679dB. In addition, the attenuation is 28.052dB at 4.7GHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.607-612
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• 2003

In this paper, a miniaturized parallel coupled bandpass filter using multi-layered LTCC(Low Temperature Co-fired Ceramics) substrate for SOP(System-On-Package) is proposed for applications to wireless communication systems. The fabricated BPF is composed of five 106$\mu\textrm{m}$ thick LTCC layers and its size is 5.24mm ${\times}$ 4.3mm${\times}$ 0.53mm. The measured characteristics of the BPF show the center frequency of 5.8GHz, bandwidth of 200㎒, insertion loss of 2.326㏈ and return loss of 13.679㏈. In addition, the attenuation is 28.052㏈ at 4.7GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.118-125
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• 2007

Harmonic band of bandpass filter(BPF) is suppressed using coupled mushroom structure. Between double positive (DPS) transmission line such as microstrip and double negative(DNG) transmission line such as one dimensional mushroom structure, strong coupling broadly arises in the cross range of dispersion curves of isolated microstrip and mushroom structure because of complex propagation constant in the cross range. Strong coupling inhibits wave propagation, so that this kind of structure can be utilized as bandstop filter(BSF). This BSF utilizes coupled transmission line instead of coupled resonator, resulting in broad bandwidth(>30 %), shan-rejection, and high rejection level. The strong coupling between DPS and DNG transmissionline makes it possible shorten coupling length, resulting in compact size. In this paper, parallel coupled BSF having center frequency of 4 GHz and 3 dB fractional bandwidth of 40 % is designed and utilized to suppressed spurious mode of two bandpass filters.

• Journal of electromagnetic engineering and science
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• v.10 no.1
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• pp.28-34
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• 2010

This paper introduces a new U.S. ultra-wideband(UWB: 3.1~10.6 GHz) 1:2 power divider based on a single section Wilkinson type configuration. The divider provides very flat in-band power splitting, high isolation, low insertion loss, sharp roll-off bandpass filtering, and DC blocking characteristics. The circuit consists of a $\lambda$/4 Y resonator, three capacitively coupled $\lambda$/2 short-circuited lines, and a resistor between the two output ports. The circuit structure was simulated with ADS and HFSS, and realized with low-temperature co-fired ceramic(LTCC) green tape, which has a dielectric constant of 7.8. $|S_{11}|$ better than 10 dB, $|S_{21}|$ and $|S_{31}|$ less than 3.2 dB, with both $|S_{22}|$ and $|S_{32}|$ measured as better than 12 dB for the whole UWB band. Measurement results agree closely with HFSS simulation results. The power divider has a compact size of $4\times9\times0.6mm^3$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.323-332
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• 2009

In this paper, we introduce a modified short-circuited stub bandpass filter suitable for ultra-wideband(UWB) applications utilizing low temperature co-fired ceramic(LTCC) technology. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate($\varepsilon_r$ = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter has been measured with an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49 % has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are $4{\times}8{\times}0.57\;mm^3$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.59-60
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• 2018

In this paper, we studied a design method for a band-pass waveguide filter with a modified H-type resonant iris (RI) placed in a thin transverse wall of a rectangular waveguide. The horizontal straight gap at the center of a conventional H-shaped iris is modified to a U-shaped one to increase the equivalent capacitance, and the equivalent inductance is improved by changing the vertical two straight slots into C-shaped ones. A third-order band pass filter using the proposed modified H-shaped iris was designed and, it was observed that the filter operated in the frequency range of 9.22-9.75 GHz with its insertion loss of 0.5 dB and return loss of 17 dB.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.496-500
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• 2003

In This paper, a pole-zero optimized design method for multi-layed planar interdigital stripeline linear group delay bandpass filter with tap input port is presented. As a design example, a four-pole group delay filter with center frequency of 2.14GHz, bandwidth of 160MHz, and group delay variation of ${\pm}0.1nS$ for LTCC technology or multilayerd PCB technology is designed. In the design process, as well the whole structure is not necessary to be simulated, and within three times of optimizing process we have good result as well. This design method could be useful for controlling error correction of manufacturing process as well as design stage.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.638-648
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• 2003

An active capacitance circuit is analyzed in depth and its application to active RF BPF with low noise figure is discussed. The characteristics of the active capacitance circuit made of FET[1] exhibits negative resistance and conventional capacitance, which is easily controlled. However, it is difficult to make the negative resistance adequate in the designated frequency range due to the lack of detailed analysis, which could make an active circuit unstable as the frequency is going higher or lower. In this paper, we analyzed the negative resistance characteristics of active capacitance circuits and also presented the method that the flatness of passband can be controlled. Finally we have designed a 4-stage active BPE, which results in bandwidth of 100 MHz, 0,04 dB insertion loss, 0.2 dB ripple, and noise figure of 2.4 dB at 1.75 GHz band.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1929_1930
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• 2009

Fully embedded tunable bandpass filter (BPF) with inductive coupling circuits is newly designed and demonstrated for UHF TV tuner ranged from 500MHz to 900MHz receivers. Conventional RF tuning circuit with an electromagnetic coupled tunable filter has several problems such as large size, high volume, and high cost, since the electromagnetic coupled filter is comprised of several passive components and air core inductors to be assembled and controlled manually. To address these obstacles, compact tunable filter with inductive coupling circuit was embedded into low cost organic package substrate. The embedded filter was optimally designed to have high performance by using high Q spiral stacked inductors, high dielectric $BaTiO_3$ composite MIM capacitors, varactor diodes. It exhibited low insertion loss of approximately -2dB, high return loss of below -10dB, and large tuning range of 56.3%. It has an extremely compact size of $3.4{\times}4.4{\times}0.5mm^3$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.590-598
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• 2004

An active capacitance circuit which employs series feedback network for the implement of negative resistance and low noise operation is analyzed in depth and its application to low noise active RF BPF's is discussed. Whereas many authors reported a lot of circuits that embody negative resistance circuit most of them have concerns for the equivalent resistance and reactance value at the center frequency. In this case, it could be possible to face a problem that the negative resistance circuit becomes unstable, or have poor flatness in passband because of insufficient forecast for the negative resistance values as the frequency goes higher or lower. In this paper, we extracted the exact equivalent values of this circuit and analyzed the RF characteristics with the varying the values of active devices and feedback circuits and presented the method that the flatness of passband can be improved. We have designed a 4-pole active BPF, which has the bandwidth of 60 ㎒, 0.67 ㏈ insertion loss, 0.3 ㏈ ripple, and noise figure of 3.0 ㏈ at 1.99 ㎓ band.