Yongsup Kim

System-Level Time-Domain Behavioral Modeling for A Mobile WiMax Transceiver

The time-domain baseband equivalent model for a mobile WiMax, IEEE 802.16e RF transceiver has been addressed in this paper. The baseband equivalent model is built up based on complex signals and spectrum. Nonlinearity up to the fifth order harmonics is considered, and noise characteristics are modeled in time domain for amplifiers and mixers. The time-domain phase noise is also implemented as part of PLL-based local oscillators. The non-ideal parameters, DNL and INL, are defined to describe non-linearity of ADC and DAC. With this behavioral models implemented on Matlab/Simulink environment, the performance of a complete mobile WiMax transceiver can be evaluated and predicted before an actual hardware design

Systematic Analysis Methodology for Mobile Phone's Electrostatic Discharge Soft Failures

A systematic analysis methodology for mobile phones electrostatic discharge (ESD) soft failures is proposed. The proposed analysis methodology consists of two parallel processes: one is the ESD simulation and the other is the ESD characterization of the mobile phone. The ESD simulation models that consist of the ESD generator, the ESD testing setup, and a mobile phone are also developed and their accuracy is experimentally verified. The proposed methodology is applied to design the countermeasures against the ESD soft failure of the slide-type mobile phones and the root causes of the ESD soft failures are analyzed. The RC low-pass filters are designed to improve the ESD immunity of the mobile phone and the ESD simulation results of the improved mobile phone show more than 82% voltage-level reductions of the signals, which cause the ESD soft failures. In order to verify that the reduced voltage levels, actually, solve the problem of ESD soft failures, the improved mobile phones ESD immunity is characterized again, and no ESD soft failure is detected.

Analysis of mobile phone's immunity to electrostatic discharge soft failures

A technique for the analysis of mobile phones immunity to the electrostatic discharge (ESD) soft failures is proposed. First, a mobile phone, ESD simulator and ESD testing setup are modelled and then the simulation is performed using time-domain full-wave electromagnetic simulator. The proposed technique is applied to the analysis of ESD soft failure of mobile phones and the root causes of the ESD soft failure are investigated. ESD voltages obtained from simulation are compared to that from measurement. Also, improvement in the frequency of occurrence of ESD soft failure by the application of countermeasures derived from ESD simulation result is presented.

Performance improvement methodology of isolation in a dual-standby mobile phone by optimizing antenna topology and position

The mutual coupling between two internal antennas using same communication band in simplified dual-standby simulation model has been researched. Furthermore, the excited current distributions on the PCB and the electric field distributions in the near field have been investigated as the cause of coupling. In terms of antenna type, PIFA type antenna was better than monopole type in the isolation viewpoint in dual-standby phone (max. 8~9 dB). Also, in terms of feed position, position 1 and 4 was the best through all positions which can be combined from 6 feed positions of Fig. 1. The coupling difference between min. and max. was 4.5 dB in monopole, 10.8 dB in PIFA. The results will be used to guidelines in the initial stage of phone design for achieving new specifications with respect to isolation of dual-standby phone.

Systematic design technique for improvements of mobile phone's immunity to electrostatic discharge soft failures

A systematic design technique for the improvements of the mobile phones immunity to the electrostatic discharge (ESD) soft failures is proposed. The design technique consists of two parallel processes; one is the ESD simulation and the other is the ESD characterization. The modeling methods of the mobile phone, the ESD gun and the ESD testing setup for the ESD simulations are also developed. The proposed technique is applied to design the countermeasures against the ESD soft failure of the slide-type mobile phone and the root causes of the ESD soft failure are analyzed based on the proposed technique. The RC low pass filters are designed to improve the ESD immunity of the mobile phone and the ESD simulation results of the improved mobile phone show more than 82% voltage level reductions of the signals which cause the ESD soft failure. The improved mobile phones ESD immunity is characterized again and no ESD soft failure is detected.

An accurate modeling technique for the estimation of the radiation performance of commercial mobile phone with use of the M-CAD data

This paper presents an accurate modeling technique to estimate radiation performance of commercial bar type mobile phone by using the mechanical-CAD data. In particular, important parts of radiation performance such as a LCD module, a PCB, antenna feed area, a FPCB and an EMI sheet are finely considered to model. Simulation results of the radiation efficiency and specific absorption rate (SAR) are compared with the measurement data at GSM/DCS bands to verify the accuracy of the simulation model.

An electromagnetic modeling oriented RF co-simulation platform for the mobile handset application

A RF co-simulation platform consisting PCB electromagnetic (EM) modeling and behavioral modeling has been proposed for the wireless handset application. Through integration of EM PCB pattern models, RF component models and RF transceiver behavioral models, complete RF co-simulation could be accomplished. Established simulation platform has been applied to 1800 MHz CDMA mobile phone (Korean PCS) and shows that simulation results are very close to measurement results. This co-simulation platform enables predicting RF performance before prototyping through analysis of S-parameter characteristics and overall RF functionalities such as ACPR FER and STD.

Calculation of total isotropic sensitivity considering digital harmonic noise of mobile phone

This paper introduces an efficient method to calculate the total isotropic sensitivity (TIS) of a mobile phone. The method is implemented by using the EM simulation, the digital signal modeling and the RF link budget simulation. By considering digital harmonic noise, the accuracy of the TIS calculation can be increased. Simulation results for the phone structure show the availability of this proposed method.

Digital to RF coupling analysis methodology for mixed-signal systems

Digital harmonics could be coupled to a RF system in a digital & RF mixed signal board or a package. The coupled digital harmonic could reduce the RF sensitivity of the system, or cause a system failure. Digital to RF coupling is the most important factor of degrading mixed-signal systems. The analysis methodology of evaluating the RF performance reflected by the digital harmonics is addressed. In this paper, proposed methodology has been applied to RF receiver hardware and verified by 3D electromagnetic simulation.

A technique of suppressing coupling for handset applications using a Shorted Radiation Structure (SRS)

A novel technique of suppressing coupling between two main antennas is presented. By inserting complementary radiation structure that is shorted (shorted radiation structure: srs), coupling between antennas in the commercial handset is dramatically decreased without the variation of return losses and efficiency.