Woo-Sung Lee

RF Front-End Passive Circuit Implementation Including Antenna for ZigBee Applications

This paper presents a front-end passive circuit module for ZigBee applications using low-temperature co-fired ceramic technology. The front-end part consists of an antenna, a bandpass filter, a switch, and two baluns. In antenna design, the solenoid shape is employed for reducing the size of the antenna, resulting in an overall size of 9times16.4times1.82 mm3 and a gain of -1.4 dBi. As for the filter, two types of filters are suggested. First, the lumped-type filter employing a high-Q spiral inductor has more than 20-dB attenuation at both stopbands, very near to the passband. Secondly, the semilumped-type filter adopting an edge coupled line and a loading capacitor provides a group delay of below 5 ns and is adequate for the full module structure due to the structure flexibility. A balun is evaluated using lumped components instead of a transmission line and, thus, it provides an insertion loss of only 0.3 dB and a phase difference of 180deg between balanced signals. Based on these components, an RF front-end module including attaching pads for an RF integrated circuit (IC) and baseband IC is implemented. In case of using the lumped-type filter, the insertion loss of the front-end module is 6.5 dB, and the group delay is below 7 ns. In case of adopting the semilumped-type filter, the insertion loss is 6.2 dB, and the group delay is below 4 ns. The overall size of the former and latter is 25.14times28.5times0.68 mm3 and 25.66times25.58times1.17 mm3, respectively

Hybrid Current-Mode Class-S Power Amplifier With GaN Schottky Diode Using Chip-On-Board Technique for 955 MHz LTE Signal

This paper presents a gallium nitride (GaN)-based hybrid current-mode class-S (CMCS) power amplifier (PA) using a bandpass delta-sigma modulator (BPDSM) for a 955-MHz LTE signal. To enhance the drain efficiency of the CMCS PA, the chip-on-board (COB) technique, which can reduce the external parasitic components of the packaged transistor and allow fast switching operation at high frequencies by minimizing distortion of the pulse waveform, is adopted. Also, GaN Schottky barrier diodes are fabricated in-house to protect the switching transistor against the high negative voltage swing. The differential output filter and balun composed of lumped LC resonators are integrated at the back of the switching transistor to extract amplified LTE signal from the output rectangular waveform, and the fabricated CMCS PA is measured and analyzed at four different states of BPDSM according to the coding efficiency from different input power level to obtain higher power and efficiency. Finally, a cavity bandpass filter (BPF) is added to the output circuit for a more accurate reduction of the harmonics and out-of-band noise signals to enhance system efficiency. From the measured results for an 8.5-dB PAPR 3 G LTE 10-MHz input signal, the proposed CMCS PA has a maximum average output power of 37.61 and 30.78 dBm, and the resulting drain efficiencies of 33.3% and 38.6% with the drain voltage of 19 and 7 V, respectively.

A Compact Ultrawide Bandpass Filter on Thin-Film Substrate

This paper presents the ultrawideband filters for UWB fullband (range of 3.1-10.6 GHz) applications. This filter consists of ring filter for wide-bandwidth and coupled line structure for suppressing unwanted passband in upper and lower stopbands. Especially, the filter structure was realized on silicon substrate using thin film technology, adequate for wafer level packaging, which can be integrated with CMOS UWB chipset that is currently on development. To minimize the dimension of the filter, the Hilbert structure was applied in ring filter and the meander shaped broadside coupled structure was also adopted in the coupled line structure. The size of the fully realized filter structure is 4.4 x 3.6 mm 2 . The insertion loss in passband is 1.5 dB and the return loss is larger than 15 dB, respectively. The group delay in center frequency is 0.2ns and the group delay variation is less than 0.15 ns.

Evaluation of GaN Transistors Having Two Different Gate-Lengths for Class-S PA Design

This paper presents a characteristic evaluation of commercial gallium nitride (GaN) transistors having two different gate-lengths of 0.4μm and 0.25-μm in the design of a class-S power amplifier (PA). Class-S PA is operated by a random pulse-width input signal from band-pass delta-sigma modulation and has to deal with harmonics that consider quantization noise. Although a transistor having a short gate-length has an advantage of efficient operation at higher frequency for harmonics of the pulse signal, several problems can arise, such as the cost and export license of a 0.25-μm transistor. The possibility of using a 0.4-μm transistor on a class-S PA at 955 MHz is evaluated by comparing the frequency characteristics of GaN transistors having two different gate-lengths and extracting the intrinsic parameters as a shape of the simplified switch-based model. In addition, the effectiveness of the switch model is evaluated by currentmode class-D (CMCD) simulation. Finally, device characteristics are compared in terms of current-mode class-S PA. The analyses of the CMCD PA reveal that although the efficiency of 0.4-μm transistor decreases more as the operating frequency increases from 955 MHz to 3,500 MHz due to the efficiency limitation at the higher frequency region, it shows similar power and efficiency of 41.6 dBm and 49%, respectively, at 955 MHz when compared to the 0.25-μm transistor.

A ultrawideband low noise amplifier using metamorphic HEMT on organic substrate

The U.S. Federal Communications Commission (FCC) approved the unlicensed use of ultra- wideband (UWB) (range of 3.1-10.6 GHz) for commercial purposes in 2002 [1]. The chip-set for lowband (range 3.1-4.8 GHz) application has already been developed and UWB system for lowband has been evaluated by many companies. But the chip-set for full-band (range of 3.1-10.6 GHz) is on its developing stage. Therefore, various researches on the active devices like LNA, PA and the passives like filter, balun, antenna for full-band application are being performed vigorously [2], [3]. High electron mobility transistors(HEMTs) have played an important role in applications at millimeter wave ranges due to its high speed, low noise characteristics. Focusing on the low noise and high gain characteristics of the devices, applications at 3.1-10.6 GHz, utilizing pseudomorphic HEMT(pHEMT) has reported with excellent performance [4]. Motivated by this we have fabricated balanced low noise amplifier for UWB application utilizing metamorphic InAlAs/InGaAs HEMTs(MHEMT) on GaAs substrate. For the wideband amplifier evaluation, the balanced amplifier with the broadband coupler was designed and realized using multilayer organic substrate based on the ceramic- polymer composite materials developed in this work.

Development of High-Performance Band Pass Filter in the V-Frequency Band using Multilayer MCM-D Technology

Novel system-on-package (SOP)-D technology to improve the mechanical and thermal properties of a MCM-D substrate was suggested. Based on this investigation, the band pass filter for the V-band application with unique circuit and structure was designed and implemented using 2-metals, 3-BCB layers. In the mean while the effective electrical conductivity of metal layer was extracted and its value was 4times107/7 Sm. The insertion loss of band pass filter at 55 GHz was 2.6 dB and group delay was below 0.06 ns. In filter structure, loading capacitor operates as a frequency controller without distortion of inband performance. Suggested MCM-D substrate with band pass filter can be used to evaluate mm-wave system including flip-chip bonded MMIC. In final manuscript, the electrical characteristics of BCB layer upto mm-wave region using ring, T resonator method will be included

Fabrication and characterization of thermally conducting laminate using spherical aluminum nitride powders and synthesized twin mesogenic epoxy oligomer

Thermally conducting insulation laminates with high peel strength as well as high thermal conductivity were fabricated by the addition of sintered spherical A1N powders as fillers into twin mesogenic epoxy matrix. A twin mesogenic epoxy oligomer based on biphenyl structure was synthesized. Bimodal or trimodal fillers were added to the synthesized epoxy resin with a curing agent and formed to an insulation laminate, and the thermal conductivity of the cured laminate was measured. Aluminum nitride powders having average size 50 and 10um were used as the bimodal fillers. In particular, 50um A1N powders are sintered spherical particles with narrow size distribution. In addition, 5um BN powders were used the third fillers. The thermal conductivity of the cured thermoset without fillers was over 0.236 W/m-K and that of the thermally conducting laminate reached about 12.55 W/m-K at 75vol% filler loading. Cu peel strength of about 16 N/cm was obtained by 90° peel method. The 20vol% BN-replaced composite showed the higher thermal conductivity of 15 W/m-K.

A diplexer by various embedding method

In this paper, two kinds of processes in organic substrate are adopted for the evaluation of diplexer. First, the heterogeneous organic material system with FR-4 for low-k and BT for high-k is applied for GSM/DCS dualband diplexer and as a result the size decreases by 65% in the comparison with that of homogeneous material system within maintaining the performance of diplexer. This method of using various dielectric materials is more compatible in organic substrate than in ceramic system because the matching of shrinkage in sintering process is not needed in organic multilayer system. Second, the chip insertion method is verified in this research. The passive components like chip inductor and chip capacitor for diplexer are inserted in the organic substrate and the electrical performance and the reliability against thermal attack are examined. As a result, the evaluated diplexer shows almost same electrical performance with that of embedded one and good reliability against thermal attack. Therefore, the method verified in this paper can be applied for high-valued chip components integration in system in package with good reliability.

A Compact Balanced Filter on Thin Film Substrate for mmWave application

Seoul National University. School of Electrical Engineering and Computer Science San 56-1 Shillim-dong, Kwanak-gu, Seoul 151-742, Korea Electronic Materials & Packaging Research Center, Korea Electronict Technology Institute #68 Yatap-dong, Bundang-gu, Seongnam-sei, Gyeonggi-do 463-816, Korea Phone: +82-31-789-7217 E-mail: ychs@keti.re.kr Interconnect Product & Technology System LSI Division, Samsung Electronics CO., LTD. San #24 Nongseo-ri, Giheung-eup, Yongin-si, Gyeonggi-do 449-711, Korea

An ultrawide bandpass filter using ceramic multilayer configuration

An ultrawide bandpass filter with sharp rejection and wider stopband is designed and implemented using multilayer ceramic configuration. The proposed filter is composed of a broadside coupled structure and a ring type filter with an embedded stripline stub. The measured results show that the fractional bandwidth and upper stopband of the proposed filter are 106% and better than -30 dB, respectively. The insertion loss is less than 1 dB, and group delay is less than 0.3 ns in the passband. In addition, ring and broadside coupled gap structures are characterized and compared to the proposed structure.