• Journal of IKEEE
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• v.23 no.2
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• pp.474-478
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• 2019

In this paper, we analyze the degradation of receiving sensitivity due to the coupling between digital noise and mobile handset antenna using characteristic mode. First, we analyze the coupling mechanism between the antenna and digital noise, and analyze the role of the decoupling capacitor of the ground signal line, which is one of the ways to improve the antenna receiving sensitivity degradation due to camera noise. For the analysis, the digital signal line and the ground line of the FPCB of the camera module are modeled as a loop type feeder that excites the characteristic mode of the PCB ground, and improved model which has a ground line with a capacitor are analyzed.

• Journal of IKEEE
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• v.23 no.3
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• pp.873-877
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• 2019

In this paper, we analyze the degree of digital noise coupling for Inverted F Antenna (IFA) and Loop Antenna, which are representative types of portable terminal antenna, using characteristic mode. Firstly, the degree of coupling according to the direction of digital signal lines and characteristic mode current of the printed circuit board (PCB) including the antenna is compared and analyzed, and based on this result, the coupling between WiFi antenna and the front camera noise is analyzed. For analysis, the digital signal line and ground line of the FPCB of the camera module are modeled as a loop feeder that excites the characteristic mode of the PCB ground and the change of noise coupling according to the antenna types are analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.233-238
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• 2003

With the growth of high speed circuit, unwanted system noise is increased and multipoint ground is used to reduce this noise. PCB screw ground structure has radiation noise by ground loop between screws. In order to solve this problem, in this paper, we proposed improved PCB ground structure. Proposed structure improves noise absorption by using microwave absorber and conductive copper tape. We measured radiation PCB noise in the range of 1 ㎓ to 3 ㎓ to investigate proposed structure usefulness. From these results, under 2 ㎓ range proposed structure has noise reduction by 2.62 dBuV/m, which compared with screw ground.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.241-246
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• 2007

This paper presents two novel compensation circuits for leakage current and power supply noise (PSN) in phase locked loop (PLL) using a nanometer CMOS technology. The leakage compensation circuit reduces the leakage current of the charge pump circuit and the PSN compensation circuit decreases the effect of power supply variation on the output frequency of VCO. The PLL design is based on a 32nm predictive CMOS technology and uses a 0.9 V power supply voltage. The simulation results show that the proposed PLL achieves 88% jitter reduction at 440 MHz output frequency compared to the PLL without leakage compensator and its output frequency drift is little to 20% power supply voltage variations. The PLL has an output frequency range of 40 $M{\sim}725$ MHz with a multiplication range of 1-1023, and the RMS and peak-to-peak jitter are 5psec and 42.7 psec, respectively.

• Journal of electromagnetic engineering and science
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• v.3 no.2
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• pp.118-125
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• 2003

This paper presents a 5.8-㎓ oscillator that uses a novel defected ground structure(DGS), which is etched on the metallic ground plane. As the suggested defected ground structure is the structure for mounting an active device, it is the roles of a feedback loop inducing a negative resistance as well as a frequency-selective circuit. Applying the feedback loop between the drain and the gate of a FET device produces precise phase conversion in the feedback loop. The equivalent circuit parameters of the DGS are extracted by using a three-dimensional EM simulation ,md simple circuit analysis method. In order to demonstrate a new DGS oscillator, we designed the oscillator at 5.8-㎓. The experimental results show 4.17 ㏈m output power with over 22 % dc-to-RF power efficiency and - 85.8 ㏈c/Hz phase noise at 100 KHz offset from the fundamental carrier at 5.81 ㎓.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.12-22
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• 1999

Operation of an electromagnetic shaker system using a Class-D amplifier may cause unacceptable electromagnetic interference to another electronic system, requiring the user to take whatever steps are necessary to correct the interference. A differential amplifier in a Class-D amplifier is used to decrease the effect of a common-mode noise voltage in a shaker system. To prevent a ground loop, a transformer is inserted in another shaker system. These methods show reduction of the unwanted vibration which has occurred before. A transformer in a charge amplifier was used to prevent a ground loop in a shaker system using a Class-AB amplifier a few years ago, but it was susceptible of noise in a shaker system using a Class-D amplifier. Hence we corrected a ground loop between a charge amplifier and a vibration control/analysis system without a transformer. The usefulness of this approach is illustrated by the results of experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.431-436
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• 2009

As the telecommunication lines bring into widespread use, one of the most important aspects related to power distribution systems is effectively to evaluate the effect on the telecommunication lines from power lines. One of the efficient methods to evaluate the effect is to measure the induced voltage of a telecommunication line as a result of a ground-loop. If the power lines cause high induced voltage, the ground reference in the telecommunication lines is no longer a stable potential, so signals may ride on the noise. A ground loop is common wiring conditions where a ground current may take more than one path to return to the grounding electrode at the arrangement between the power lines and telecommunication lines. When a multi-path connection between the power lines and telecommunication line circuits exists, the resulting arrangement is known as a ground loop. Whenever a ground loop exists, there are potential for damages or abnormal operations of the telecommunication lines. The power lines can induce the voltage on the communication line. The effects can be calculated by considering the inductances and capacitances. However, if we assume that there are only power lines, it doesn't have a practical meaning because there are conductors with other purpose in the neighborhood of the lines. If we consider that case, we need more complex system. Therefore we suggest more complex system considering the conductors with other purpose in the neighborhood of the lines. The neutral wires and the overhead ground wires are considered for calculating the induced voltage. We assume that there are the messenger wires beside the power line as a result of increased use of them. The main purpose of this paper is a study on a shielding effect of messenger wires in the distribution lines. EMTP(Electro-Magnetic Transients Program) program is used for the induced voltage calculation.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1955-1957
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• 2003

This paper presents a novel defected ground structure (DGS) and its application to a microwave oscillator. The presented oscillator is designed so as to use the suggested defected ground structure as a feedback loop inducing a negative resistance as well as a frequency-selective circuit. Applying the feedback loop between the drain and the gate of a FET device produces precise phase conversion in the feedback loop. The equivalent circuit parameters of the DGS are extracted by using a three-dimensional EM calculations and simple circuit analysis method. The implemented 1.07 GHz oscillator exhibits 0 dBm output power with over 15% dc-to-RF power efficiency and -106 dBc/Hz phase noise at 100 kHz offset from carrier.

• Journal of Korean Society of societal Security
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• v.2 no.3
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• pp.39-46
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• 2009

A small loop-loop multi-frequency electromagnetic(EM) induction method is a useful technique to map a resistivity distribution efficiently and non-destructively. However, for quantitative interpretation and depth sounding, the quality of measured data is crucial. In this paper, we propose a bias correction of measured data by using background noise measurements to obtain reliable data, and propose an evaluation technique of apparent that can provide a resistivity image easily. We have performed small loop-loop EM measurements to detect water saturation in a man-made test site. The application of our proposed techniques to the measured data was successful.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.6
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• pp.497-504
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• 2021

This paper presents improvement of the reception noise suppression method during formation flights of aircraft. Since aircraft communication equipment is very important for flight mission and safety to perform the functions of internal/external communications, it is required to implement noise-free, clean communication quality, and transmitting/receiving functions. Therefore, the FTA (Fault Tree Analysis) analysis and failure search were performed on the reception noise, and the internal noise of the intercom that affected the reception noise and the none-transmition phenomenon was identified. We changed the multiple grounds of the intercom to a single ground and applied an improved method of filtering the DC Offset voltage. As a result, the voice quality of the communication system of the aircraft was improved through the reduction of the reception noise during formation flights, and it was verified by ground and flight tests.