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A Fully Integrated Dual-Band WLP CMOS Power Amplifier for 802.11n WLAN Applications
Seungjun Baek,Hyunjin Ahn,Hyunsik Ryu,Ilku Nam,Deokgi An,Doo-Hyouk Choi,Mun-Sub Byun,Minsu Jeong,Bo-Eun Kim,Ockgoo Lee 한국전자파학회JEES 2017 Journal of Electromagnetic Engineering and Science Vol.17 No.1
A fully integrated dual-band CMOS power amplifier (PA) is developed for 802.11n WLAN applications using wafer-level package (WLP) technology. This paper presents a detailed design for the optimal impedance of dual-band PA (2 GHz/5 GHz PA) output transformers with low loss, which is provided by using 2:2 and 2:1 output transformers for the 2 GHz PA and the 5 GHz PA, respectively. In addition, several design issues in the dual-band PA design using WLP technology are addressed, and a design method is proposed. All considerations for the design of dual-band WLP PA are fully reflected in the design procedure. The 2 GHz WLP CMOS PA produces a saturated power of 26.3 dBm with a peak power-added efficiency (PAE) of 32.9%. The 5 GHz WLP CMOS PA produces a saturated power of 24.7 dBm with a PAE of 22.2%. The PA is tested using an 802.11n signal, which satisfies the stringent error vector magnitude (EVM) and mask requirements. It achieved an EVM of -28 dB at an output power of 19.5 dBm with a PAE of 13.1% at 2.45 GHz and an EVM of -28 dB at an output power of 18.1 dBm with a PAE of 8.9% at 5.8 GHz.
Contact Resistance of Inkjet-Printed Silver Source–Drain Electrodes in Bottom-Contact OTFTs
Seungjun Chung,Jaewook Jeong,Donghyun Kim,Yunhwan Park,Changhee Lee,Yongtaek Hong IEEE 2012 Journal of display technology Vol.8 No.1
<P>In this paper, we report contact resistance analysis between inkjet-printed silver source-drain (S/D) electrodes and organic semiconductor layer in bottom-contact organic thin-film transistors (OTFTs) using transmission line method (TLM). Inkjet-printed silver electrodes, spin-coated PVP and evaporated pentacene were used as gate and S/D electrodes, gate dielectric layer and semiconductor layer, respectively. On a common gate electrode, S/D electrodes with various channel length from 15 to 111 m were printed for TLM analysis. The same bottom-contact OTFT with evaporated silver S/D electrodes was also fabricated for reference. We extracted contact resistances of 1.79 M cm and 0.55 M cm for inkjet-printed and evaporated silver electrodes, respectively. Higher contact resistance for inkjet-printed silver electrodes can be explained in terms of their relatively poor surface properties at electrode edge that can cause small pentacene molecule grain or slight oxidation of surface during the printed silver sintering process.</P>
Flexible memristive memory array on plastic substrates.
Kim, Seungjun,Jeong, Hu Young,Kim, Sung Kyu,Choi, Sung-Yool,Lee, Keon Jae American Chemical Society 2011 Nano letters Vol.11 No.12
<P>The demand for flexible electronic systems such as wearable computers, E-paper, and flexible displays has recently increased due to their advantages over present rigid electronic systems. Flexible memory is an essential part of electronic systems for data processing, storage, and communication and thus a key element to realize such flexible electronic systems. Although several emerging memory technologies, including resistive switching memory, have been proposed, the cell-to-cell interference issue has to be overcome for flexible and high performance nonvolatile memory applications. This paper describes the development of NOR type flexible resistive random access memory (RRAM) with a one transistor-one memristor structure (1T-1M). By integration of a high-performance single crystal silicon transistor with a titanium oxide based memristor, random access to memory cells on flexible substrates was achieved without any electrical interference from adjacent cells. The work presented here can provide a new approach to high-performance nonvolatile memory for flexible electronic applications.</P>
Characteristics of HfN Films Deposited by Using Remote Plasma-enhanced Atomic Layer Deposition
전형탁,Wooho Jeong,Youngbin Ko,Seokhwan Bang,Seungjun Lee 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.3
HfN films were deposited by using remote plasma-enhanced atomic layer deposition (RPALD)with tetrakis-dimethylamino-hafnium {TDMAH, Hf[N(CH3)2]4} as a Hf precursor and a N2 plasma as a reactant. The growth rate of the HfN films was about 0.2 nm/cycle in the process window of 150 - 250℃ The optimized process temperature, plasma power, and pressure were 250 ℃,300 W, and 1 Torr, respectively. The as-deposited film was slightly nitrogen-rich, and the nitrogen content decreased slightly after in-situ vacuum annealing at 700 ℃ for 10 min. HfN films deposited on contact holes (0.12-µm wide and 1.8-µm deep) showed excellent conformal coverage. Barrier characteristics were observed in the Cu/HfN/Si samples after annealing at various temperatures,and the formation of a copper silicide phase was observed after annealing at 650 ℃.