• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.294-301
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• 2000

One of the most important design parameters in a microwave radio transmitting system is to reduce spurious response from the output spectrum of the transmitting system. A Local oscillator (LO) is seldom totally pure and at the least contain some LO harmonic signals. A LO or any oscillator is a transmitter if provided with a suitable radiator, conduction, or leakage path. Where mixer is employed in the output of the LO mixer generated spurs can be increased by RF amplifier. To reduce LO leakage, notch filter or band pass filter has been conventionally used. In this paper, the leakage reduction(LR) signal, which has the same magnitude and the opposite phase with respect to LO leakage signal, is added to the output of mixer of the wireless LAN system. The LO leakage is reduced by 30 dB more than the conventional methods do. The proposed method is potentially suitable for low-cost, reliable, and simple application of monolithic microwave integrated circuits (MMICs)

• Journal of Convergence for Information Technology
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• v.10 no.8
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• pp.47-52
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• 2020

In this study, a simulation investigation was conducted on the method of reducing switching noise and spurious emission among design methods for step-down DC-DC converter modules for automotive. A typical 4-layer converter circuit using a PMIC(Power Management Integrated Circuit) chip was presented, and the simulation results of conductive emissions at two input terminals (+, -) and the point between the input filter and the PMIC was performed in the 1.0~5.0MHz band and the 100MHz band. The results for the conducted and radiated emissions in the HF(3~30MHz) and VHF(30-300MHz) bands were presented. It showed an improvement of about 10dB over the bands by routing the output terminal placed on the 3 or 4-layer in the opposite direction to the input terminal. The result of this study is expected to be useful in the design of the DC-DC converter modules in the future because it gives a better improvement compared to the existing methods.