• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.157-159
• /
• 2010

Most digital cameras apply a Charge Coupled Device(CCD) Sensor or a Complementary Metal Oxide Semiconductor(COMS) Sensor. And the images captured these sensors include unwanted noises. In this paper, we proposed a method of the Noise Reduction(NR) about noise reduction or recovery in the image. The proposed NR method is related to Bandwidth of the Low Pass Filter(LPF). For improvement of NR, we were changing the filter coefficient of the LPF. The results of simulations with various filter coefficients, [1 2 1] in the LPF and [-1 2 -1] in the High Pass Filter(HPF) have ideal frequency bandwidth and high performance. We proposed a filter coefficient [1 2 1] and [-1 2 -1] in the LPF and the HPF respectively.

• Current Optics and Photonics
• /
• v.7 no.4
• /
• pp.345-353
• /
• 2023

We propose a turbulence-tolerant Manchester on-off keying (M-OOK) transmission for free-space optical (FSO) communication. At the transmitter end, a M-OOK signal featuring a spectrum with low-frequency components absent is modulated and transmitted into a turbulent channel. At the receiver end, a low-pass filter (LPF) -based adaptive-threshold decision (ATD) with LPF-extracted channel-state information (CSI) and a high-pass filter (HPF)-based fixed-threshold decision (FTD) are employed to compensate for the effects of turbulence, owing to the low-frequency spectral characteristics of the turbulent channel. The performance of LPF-based ATD and HPF-based FTD are evaluated for various cutoff frequencies for the LPF and HPF. Besides, the proposed M-OOK transmission is compared to conventional non-return-to-zero OOK (NRZ-OOK) for different data rates. The proposed technique is verified in simulation. The simulation results show that the proposed M-OOK detection with optimized cutoff frequencies of LPF and HPF has better bit-error-rate (BER) performance compared to NRZ-OOK, and it is close to the theoretical ATD with the knowledge of precise CSI under various degrees of turbulence effects.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.1
• /
• pp.169-174
• /
• 2018

In this paper, a design method for a wideband LPF for harmonic suppression applications is investigated. The proposed wideband LPF is comprised of four circular slot pairs with different diameters, which are added symmetrically in the ground plane of a CPW transmission line. Four circular slot pairs act as a defected ground structure and provide a wideband low pass characteristic. The circular slot with the smallest diameter is located at the side of port 1, and the diameter of the circular slot is increased as it goes toward port 2. The low pass characteristics of each circular slot are compared with the proposed wideband LPF. The final designed LPF was fabricated on FR4 substrate, and its characteristics were tested. The measured S11 characteristic was maintained at over -3.3 dB in the frequency range of 1.89-20.00 GHz band, whereas the S21 characteristic was less than -21.4 dB in the frequency range of 2.66-20.00 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.1
• /
• pp.107-111
• /
• 2009

In this paper, the power added efficiency(PAE) of a Doherty amplifier has been improved by applying Photonic Bandgap(PBG) characteristics on the output of amplifier. As a result of the high order harmonics termination, excellent improvement in PAE, maximum output power as well as linearity is obtained. The PAE is improved as much as relatively 35% compared with a conventional Doherty amplifier. Moreover, size of LPF is reduced by PBG characteristics. Therefore the whole amplifier circuit size is considerably reduced by diminishing in size of the LPF as compared with a Doherty amplifier using conventional LPFs.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.1445-1456
• /
• 2011

This paper presents the research of Low Pass Filter(hereinafter called "LPF") which is the part of Chopper Gate Control Unit on the electric rolling stock. Chopper Gate Control Unit controling the propulsive equipments of electric rolling stock consists of several electronic parts, PCB, Power Supply, Gate Circuit Amp, Freon Cooling Device, and has been used the parts made by japan manufacturer Mitsubish. But these parts recently have been more broken down and slow down performance because of long-term use, deterioration. Most of the malfunctions are low performance of LPF. Furthermore, it is physically impossible to repair LPF. Because it is molding type part and no longer manufactured. Also it needs high cost for custom-building. Therefore, it is now making up for through self-developed LPF and operating on Busan metro 1st after on-board testing. This research performed the PS Pice simulation testing, analysis of self-developed LPF performance and the wave form characteristic by multi-function synthesizer, spectrum analyzer, oscilloscope.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.6 s.97
• /
• pp.594-602
• /
• 2005

In this paper, a new type of 5-pole low pass filter(LPF) having defected ground structure(DGS) and very wide transmission line elements is proposed. The previously presented design method of 3-stage LPF using DGS is generalized to design N-pole LPFs for $N\geq5$. As an example, a 5-pole LPF having DGS is designed and measured. The accurate curve-fitting method to determine the series inductors in the prototype filter, and ultimately the size of DGS is described. The proposed 5-pole LPF has transmission line elements with a very low impedance to realize the required shunt capacitance instead of open stubs. Therefore, open stub. Therefore, open stub, Tee-junction, Cross-junction, and high impedance line are not required for the proposed LPF, while they all have been essential in conventional LPFs.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.4 no.1
• /
• pp.13-21
• /
• 1967

A low pass filter is synthesized with R, C and negative impedance converters(NIC). The filter has a 4-th order elliptic function, which gives best magnitude approximation with equi-ripple characteristics both in pass and stop band. And experimental investigations have been made on the effect of the anticipated deviation of the NIC conversion factor and of possible loaded operation. Through the study, it has been cocluded that: 1. For minimum pole-zero sensitivity with respect to the NIC conversion factor, the network of a parallel RC-NIC configuration is preferable and the Horowitz polynomial decomposition method is applied in the synthesis procedure. 2. A few percentage variation of the NIC conversion factor changes the frequency and amplitude characteristics of the filter by nearly negligible amount. 3. With a load resistance below the critical value, the filter turns into an oscillator.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2005.11a
• /
• pp.63-68
• /
• 2005

In this paper, Coplanar Waveguide(CPW) low-pass filter with the spurious-reduced is designed by using Defected Ground Structures(DGS). Two different LPF unit cells and DGS pattern are combined to reduce the spurious. In comparison to a conventional step impedance LPF, the size of proposed LPF as 17.2mm*6.8mm is several times smaller. The simulation and measurements confirm that spurious characteristics is presented less than -30dB($S_{21}$) to three times cut off frequency.

• Journal of electromagnetic engineering and science
• /
• v.10 no.3
• /
• pp.117-120
• /
• 2010

A novel stepped-patch loaded coplanar waveguide(SPLCPW) structure is proposed and applied to the design of a low-pass filter(LPF). The stepped-patch loaded on the opposite side of the CPW plane is shown to provide a shunt-connected series L-C resonance, which is dual to that of a conventional CPW defected ground structure(DGS). As a simple example of the proposed SPLCPW circuit, a 3-pole SPLCPW LPF is designed and good results are obtained.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.10
• /
• pp.27-33
• /
• 2016

This paper proposes a Low Noise Amplifier (LNA) with chopper stabilization technique with a sample-hold circuit. Chopper stabilization technique is effective in terms of reducing low frequency offset and flicker noise. Conventional chopper amplifier has a disadvantage in area because of using Low Pass Filter (LPF) for remove chopping spike. The proposed chopper amplifier employed sample and hold technique to decrease chopping spike instead of LPF that improves 36% in voltage damping and 11% in area.