• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.5
• /
• pp.872-882
• /
• 1994

In this paper, the Low Noise Amplifier(LNA) is designed and fabricated to include a band pass filter characteristics considering the antenna system characteristics according to the transmitting and receiving signal level of communication satellite transponder. As an example, a 2-stage low noise amplifier and a 4-stage amplifier and designed, fabricated and measured at 14,0~14.5GHz of receiving frequency band. This fabricated LNA has shown the gain with very good flatness within pass-band, and its gain decreases rapidly out of band resulting in supperssion of the transmitting signal power leakage. It has shown the 20.3dB +- 0.1dB of pass-band gain, the 1.44dB +-0.04dB of noise figure and the 14dB rejection out of band(12.25~12.75GHz). The gain flatness, noise figure and group delay of this 2-stage LNA satisfactorily met the simulation results. And the fabricated 4-stage amplifier has shown the more than 42dB of pass-band gain, the +-0.25dB of flatness and the 28dB of the rejection effect for transmitting power leakage. The 2-stage LNA and 4-stage amplifier, in this paper, will bring a design margin for the input filter and also result in the system cost reduction.

• Progress in Superconductivity
• /
• v.4 no.2
• /
• pp.132-136
• /
• 2003

Extremely selective high temperature superconducting (HTS) band -pass filters were developed for the base transceiver station applications of Digital Cellular communication Service (DCS). The filters have a bandwidth of 25 MHz at a center frequency of 834 MHz. There are 12 resonators which have spiral-meander microstrip-line structures in order to reduce far-field radiations with a reasonable tunability. As a result, the size of filters is 5 mm $\times$ 17 mm $\times$ 41 mm. Device characteristics exhibited a low insertion loss of -0.4 dB with a -0.2 dB ripple and a return loss better than -10 dB in the pass-band at 65 K. The out-of-band signals were attenuated better than 60 dB about 3.5 MHz from the lower band edge, and 3.8 MHz from the higher band edge.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.1
• /
• pp.252-264
• /
• 2023

This paper proposes a design of a dual-band band-pass filter that integrates a λg/2 open SIR structure, a transmission line, and a fork-type structure with symmetric and asymmetric open stubs. To obtain the dual-band effect, the proposed filter uses the SIR structure and adjusts the impedance ratio of the SIR structure. Therefore, the position of the harmonics of the filter is shifted through the adjustment of the impedance ratio, and this can obtain a double-band effect. In order to obtain the dual-band characteristics, the dual-band effect is obtained by inserting a open stub between the SIR structures with the SIR structure divided in half. In addition, the second frequency response is obtained by adjusting the length of the open symmetrical stub in the fork-shaped structure. The asymmetrical open stub in the fork form achieves optimum bandwidth by adjusting the length. Therefore, the first center frequency of the proposed band-pass filter is 5.896 GHz and the bandwidth is 13.6 %. At this time, the measurement results are 0.13 dB and 33.6 dB. The second center frequency is 5.906 GHz and the bandwidth is 13.6 %. At this time, the measurement results are 0.15 dB and 19.8 dB. The reason is that when the impedance ratio (Δ) is higher than 1, the position of the harmonic is shifted to a lower frequency band. However, if the impedance ratio (Δ) is lowered by one step, the position of harmonics will move to a higher frequency band. The function of the filter designed using these characteristics can be obtained from the measurement result. The proposed band-pass filter has no coupling loss and no via energy concentration loss because there is no coupling structure of input/output and no via hole. Therefore, system integration is possible due to its excellent performance, and it is expected that dedicated short-range communication (DSRC) system applications used in traffic communication systems will be possible.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.3
• /
• pp.43-49
• /
• 2014

This paper presents a theoretical study of transmission performance for an optical duobinary transmitter employed a Mach-Zehnder modulator and a electrical low pass filter at 40Gbps optical communication links. It depends on the bandwidth of the low pass filter in the transmitter, the optical filter and the filter in the receiver. Also, each filter affected to the various parts of the optical power spectrum. By optimizing the bandwidth of each filter, we could control the side robes and the ripples and improve the dispersion tolerance of the transmission system.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.23 no.6
• /
• pp.950-956
• /
• 1986

In this paper, a direct addressing mode of a microprocessor is introduced to save memory capacity, and also a dedicated digital filter is constructed to speed up the filter processing and to enable an easy selection of the impulse response types. A theoretical analysis has been conducted on the errors caused by the finite word klength, rounding-off and multiplication procedures. The digital filter designed by the proposed method is made into a module which can function as a 7th-order recursive or a 14-order nonrecursive type with a simples witch operation. The proposed filter is implemented on a printed-circuit board. The frequency characteristics of this filter can be controlled by the multiplication values stored in ROMs. A low-pass, a high-pass and a band-pass filter have been designed and their frequency characteristics are verified by actual measurements. For a order higher filer, two filter modules have been cascaded into an integrated filter of 23rd-order non-recursive low-pass type and a 12th-order recursive multiband type. Their frequency characteirstics have been found to agree with the theory.

• Journal of the Korea Society of Computer and Information
• /
• v.7 no.2
• /
• pp.68-72
• /
• 2002

In this study, I studied on the principle of OTA and it's basic application. Here, I designed second order filter using OTA. This filter has three inputs and one output. If we use each one input among them, we can get a low pass, high pass and band pass output. In the result of the computer simulation. the linear characteristics was superior to the conventional Op-Amp filter. And this circuit is advantageous to making an IC. This will be used to the communication system which has the low distortion and high frequency circuit. This study will have to be continued to form a higher order filter using OTA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.12 s.115
• /
• pp.1150-1155
• /
• 2006

In this paper, the equivalent circuit of tapped-line that is applied in the band-pass filter is suggested and the value of an equivalent circuit is mathematically defined. An equivalent circuit of tapped-line is composed by open stub and transmission line that has negative electrical length, and the position of tapped-line and the value of resonator's length can be obtained by the impedance of resonator and the inverter. The new design method using equivalent circuit leads to very good agreement compared with theoretical value. The hair-pin band-pass filter using equivalent circuit of tapped-line shows the insertion loss of 1.1 dB and the return loss of 20 dB at the center frequency of 2 GHz.

• Proceedings of the KIEE Conference
• /
• 2001.11c
• /
• pp.134-137
• /
• 2001

A variable bandwidth filter (VBF) is proposed for cleaning signals with known instantaneous bandwidth (IB). Also, the behaviors and the characteristics of the VBF are examined in time-frequency domain (TFD). The proposed VBF clips a noisy signal along the boundaries of IB and rejects noise in the outside of the IB of the signal in TFD. It is possible to construct four kinds of VBF that are low-pass VBF, high-pass VBF, band-pass VBF and band-stop VBF.

• Proceedings of the KIEE Conference
• /
• 2001.11c
• /
• pp.138-141
• /
• 2001

In this paper, a VBF(variable bandwidth filter) is suggested and analyzed in time-frequency domain. There are four kinds of VBF, which are low-pass VBF, high-pass VBF, band-pass VBF and band-stop VBF. The proposed VBF can extract the components of signals within variable instantaneous bandwidth at a specific time instant. Instantaneous bandwidth is estimated in time-frequency domain. The VBF is represented by rational form in extended Fourier frequency domain.

• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.35C no.8
• /
• pp.42-51
• /
• 1998

An 8th-order elliptic low-pass filter with cutoff frequency of 3.13kHz is presented. The design procedure is based on teh 1/s impedance transformation which is applied to a minimum capacitor LC ladder network.The tranformed network is implemented with resistors and high Q frequency-dependent negative resistors (FDNR's). The high Q FDNR is realized with two transadmittance amplifiers. Detailed SPICE simulations show that the iflter has pass-band ripple of 0.18dB, stop-band attenuation over 100dB, cutoff frequency of 3.13 khz, and cutoff frequency temperature coefficient of 8.5ppm/.deg. C at supply voltage of .+-.5V.