• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1602-1609
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• 1998

In this paper, the design and implementation of the novel RF front end circuit for CDMA based PCS phone is described. This novel scheme is realized by building the power amplifier module combined with duplexer. The dielectric filters which are parts of duplexer are broken up and relocated into the module. Electromagnetic analysis for via holes and coupling between narrow transmissio lines is icluded to design a circuit. The combined moule has been minimaturized to be as small as 1.5CC. It has satisfied IS-95 requirements for linearity performances of CDMA signal at 24-dBm output power as well as played apart as a duplexer. The operating current of about 95mA has been saved owing to both rearranging dielectric filters and limiting operating point to class-B by considering real working power range of CDMA phones.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.235-240
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• 2006

Ionospheric scintillation induces a rapid change in the amplitude and phase of radio wave signals. This is due to irregularities of electron density in the F-region of the ionosphere. It reduces the accuracy of both pseudorange and carrier phase measurements in GPS/satellite based Augmentation system (SBAS) receivers, and can cause loss of lock on the satellite signal. Scintillation is not as strong at mid-latitude regions such that positioning is not affected as much. Severe effects of scintillation occur mainly in a band approximately 20 degrees on either side of the magnetic equator and sometimes in the polar and auroral regions. Most scintillation occurs for a few hours after sunset during the peak years of the solar cycle. This paper focuses on estimation of the effects of ionospheric scintillation on GPS and SBAS signals using a software receiver. Software receivers have the advantage of flexibility over conventional receivers in examining performance. PC based receivers are especially effective in studying errors such as multipath and ionospheric scintillation. This is because it is possible to analyze IF signal data stored in host PC by the various processing algorithms. A L1 C/A software GPS receiver was developed consisting of a RF front-end module and a signal processing program on the PC. The RF front-end module consists of a down converter and a general purpose device for acquiring data. The signal processing program written in MATLAB implements signal acquisition, tracking, and pseudorange measurements. The receiver achieves standalone positioning with accuracy between 5 and 10 meters in 2drms. Typical phase locked loop (PLL) designs of GPS/SBAS receivers enable them to handle moderate amounts of scintillation. So the effects of ionospheric scintillation was estimated on the performance of GPS L1 C/A and SBAS receivers in terms of degradation of PLL accuracy considering the effect of various noise sources such as thermal noise jitter, ionospheric phase jitter and dynamic stress error.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.295-301
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• 2011

A triple-band transceiver module for 2.3/2.5/3.5 GHz mobile WiMAX, IEEE 802.16e, applications is introduced. The suggested transceiver module consists of RFIC, reconfigurable/multi-resonance MIMO antenna, embedded PCB, mobile WiMAX base band, memory and channel selection front-end module. The RFIC is fabricated in $0.13{\mu}m$ RF CMOS process and has 3.5 dB noise figure(NF) of receiver and 1 dBm maximum power of transmitter with 68-pin QFN package, $8{\times}8\;mm^2$ area. The area reduction of transceiver module is achieved by using embedded PCB which decreases area by 9% of the area of transceiver module with normal PCB. The developed triple-band mobile WiMAX transceiver module is tested by performing radio conformance test(RCT) and measuring carrier to interference plus noise ratio (CINR) and received signal strength indication (RSSI) in each 2.3/2.5/3.5 GHz frequency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.703-705
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• 2016

In this paper, we developed a wideband PIMD system to measure passive intermodulation distortion signals of mobile communication RF passive module. To represent wideband characteristic, we designed a receiver that meets low-noise and wideband characteristics in RF receiver. It allows high dynamic range in the RF receiver front end. In designed passive intermodulation distortion measurement system, we programed to display a PIMD signal with FPGA/DSP at PC. Implemented PIMD system was variable from 650 MHz to 2700 MHz and show up to -138 dB minimum detectable $3^{rd}$ passive inetrmodulation distortion signal.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.93-100
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• 2009

This paper presents a step up four channel DC-DC converter using charge pump voltage doubler structure. Our goal is to design and implement DC-DC converter for capacitive SP4T RF MEMS switch in front end module in wireless transceiver system. Charge pump structure is small and consume low power 3.3V input voltage is boosted by DC-DC Converter to $11.3{\pm}0.1V$, $12.4{\pm}0.1V$, $14.1{\pm}0.2V$ output voltage With 10MHz switching frequency. By using voltage level shifter structure, output of DC-DC converter is selected by 3.3V four channel selection signals and transferred to capacitive MEMS devices. External passive devices are not used for driving DC-DC converter. The total chip area is $2.8{\times}2.1mm^2$ including pads and the power consumption is 7.52mW, 7.82mW, 8.61mW.

• Journal of IKEEE
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• v.3 no.2 s.5
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• pp.186-195
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• 1999

In this paper, the RF-modules composed of front-end, frequency synthesizer, modulator/demodulator and power control multi channel WLL personal system for W-CDMA using 10 [MHz] RF channel bandwidth has been implemented and considered. The measured transmission power is 250 [mW] which is very close to the required value. The measured flatness of power at the final output stage is ${\pm}1.5[dB]$ over the required bandwidth of the receiver. In addition, it is found that the chip rate transmitting spread signal is set to 8.192 [MHz], the required rate. The frequencies of RF_LO signal and LO signal of the modulator and the demodulator measured by a frequency synthesizer are satisfied with design requirements. The operating range of the receiving strength signal indicator and AGC units shows 60 [dB] respectively. Also the measured phasor diagram and eye pattern for deciding the RF modules compatible with baseband digital signal processing part are shown good results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2391-2396
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• 2010

The power-controlled six-port element that can control the local oscillator signal power and receiving RF signal power was designed and implemented in this paper. The direct conversion six-port element configuration was proposed, which provides the constant six-port output power by controlling the six-port input power with various signal strength. The direct conversion six-port element protects the power detector element of six-port receiver from the saturation status and compensates the transmission performance degradation. For implementation of power-controlled six-port element, the power-controlled six-port element including the power controller was analyzed. The implemented power-controlled six-port element shows the power control capability of 36 dB and gain imbalance of about 1.6 dB, phase imbalance of about $4^{\circ}$ in the frequency range of 1.69 GHz. The measured results show the good performance as direct conversion front-end element.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.7-12
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• 2008

This paper presents a lateral resistive contact RF MEMS switch using comb drive. Our goal was to fabricate the RF MEMS switch with high reliability and good RF characteristics for front end module in wireless transceiver system. Therefore, comb drive is used for large contact force in order to achieve low insertion loss and small off-state capacitance in order to achieve high isolation. The single crystalline silicon is used for mechanical reliability. As a result, the developed switch showed insertion loss less than 0.44 dB at 2 GHz, isolation greater than 60 dB, and low actuation voltage at 26 V.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1660-1661
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• 2011

본 논문에서는 7중 대역 (GSM850, GSM900, DCS1800, PCS1900, UMTS850, UMTS1900, UMTS2100) 을 지원하는 LPF 내장형 LTCC 프런트 엔드 모듈 (FEM) 을 설계, 제작 및 측정하였다. 제작된 FEM은 효과적인 고조파 제거를 위해 수동소자를 LTCC 기판에 내장하여 저역 통과 필터(LPF)를 구현하였다. 본 논문에서 제안하는 FEM은 송수신 신호를 선택하기 위한 flip-chip 형태의 CMOS RF SP9T switch, Rx 신호의 수신을 위한 dual type의 SAW filter, 매칭 및 ESD 보호 회로를 위한 0603 크기의 칩소자가 부품 외부에 실장되어 구현된다. 전체 크기는 $4.5{\times}3.2{\times}1.2\;mm^3$의 초소형으로 내부 GND 2개 층을 포함하여 총 16층으로 구성된다. 측정결과는 송신단과 수신단의 삽입손실이 각각 1.7 dB, 3.6 dB 이하의 우수한 특성을 보였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.768-772
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• 2007

Integration of RF front end module(FEM) into the antenna has been investigated in USPCS band (1.88GHz-1.99GHz). The FEM consists of input filter, power amplifier, coupler, power detector, bias switch and duplexer. The antenna was designed in planar inverted F antenna(PIFA) structure to implement it inside the handset. In order to avoid strong coupling between the antenna and FEM, a shielding ground layer was placed between them. The antenna size is 19mm by 10mm by 6mm under which FEM whose size is 8mm by 5mm by 1.5m locates. The antenna impedance was selected to match to FEM having better efficiency rather than gain since FEM has enough gain whose system spec is minimum of 20dB. The antenna patterns are shown with and without FEM.