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A Highly Efficient Dual-Mode 3G/4G Linear CMOS Stacked-FET Power Amplifier Using Active-Bypass
Unha Kim,Yong-Gwan Kim,Jung-Kin Woo,Sunghwan Park,Youngwoo Kwon 한국전자파학회JEES 2014 Journal of Electromagnetic Engineering and Science Vol.14 No.4
A highly efficient dual-mode linear CMOS stacked-FET power amplifier (PA) is implemented for 3G UMTS and 4G LTE handset applications. High efficiency is achieved at a backed-off output power (Pout) below 12 dBm by employing an active-bypass amplifier, which consumes very low quiescent current and has high load-impedance. The output paths between high-and low-power modes of the PA are effectively isolated by using a bypass switch, thus no RF performance degradation occurs at high-power mode operation. The fabricated 900 MHz CMOS PA using silicon-on-insulator(SOI) CMOS process operates with an idel current of 5.5 mA and show power-added efficiency (PAE) of 20.5%/43.5% at Pout = 12.4/28.2dBm while maintaining an adjacent channel leakage ratio (ACLR) better than -39dBc, using the 3GPP uplink W-CDMA signal. The PA also exhibits PAE of 35.1% and ACLRE-UTRA of-33 dBc at Pout = 26.5 dBm, using the 20 MHz bandwidth 16-QAM LTE signal.
A Highly Efficient GaAs HBT MMIC Balanced Power Amplifier for W-CDMA Handset Applications
Unha Kim,Youngwoo Kwon,김정현 한국전자통신연구원 2009 ETRI Journal Vol.31 No.5
A highly efficient and compactly integrated balanced power amplifier (PA) for W-CDMA handset applications is presented. To overcome the size limit of a typical balanced PA, a bulky input divider is integrated into a PA MMIC, and a complex output network is replaced with simple lumped-element networks. For efficiency improvement at the low output power level, one of the two amplifiers in parallel is deactivated and the other is partially operated with corresponding load impedance optimization. The implemented PA shows excellent average current consumption of 34.5 mA in urban and 56.3 mA in suburban environments, while exhibiting very good load-insensitivity under condition of VSWR=4:1.
A High-Efficiency SOI CMOS Stacked-FET Power Amplifier Using Phase-Based Linearization
Unha Kim,Youngwoo Kwon THE INSTITUTE OF ELECTRICAL ENGINEERS 2014 IEEE Microwave and Wireless Components Letters Vol. No.
<P>A linearization technique based on the phase correction is proposed for a CMOS stacked-FET power amplifier (PA). The linearizer employs a phase injection circuit as a main linearizer. The phase injection circuit presents envelope-reshaped capacitance to the gate of a driver amplifier to correct for phase compression near saturation. It also helps with AM-AM linearization. Hybrid bias circuit consisting of a diode and a resistor is also employed for static adaptive biasing, which allows the PA to meet stringent linearity requirement across the entire power range. Two stacked-FET linear PAs with the proposed linearizers have been designed using a silicon-on-insulator (SOI) CMOS process at 1.88 and 0.9 GHz. The fabricated PAs show adjacent channel leakage ratios (ACLRs) better than -39 dBc with peak power-added efficiencies (PAEs) of 44.3 and 49.2% at 1.88 and 0.9 GHz, respectively, using 3GPP uplink W-CDMA signal.</P>
A Multiband Reconfigurable Power Amplifier for UMTS Handset Applications
Unha Kim,Sungyoon Kang,Jungrin Woo,Youngwoo Kwon,Junghyun Kim Professional Technical Group on Microwace Theory a 2012 IEEE Transactions on Microwave Theory and Techniqu Vol. No.
<P>A new practical reconfigurable output network for a multiband reconfigurable power amplifier (PA) is proposed for universal mobile telecommunications system (UMTS) handset applications. The proposed reconfigurable network can reconfigure the output power and the output path, as well as the frequency. It consists of a power-reconfigurable network, a frequency-reconfigurable network, and a path-selection network. In this paper, its reconfiguration principle is described to extract key design parameters for the reconfigurable PA implementation. To demonstrate the performance of the proposed structure, a 5 mm × 6 mm multiband reconfigurable PA module is developed for UMTS high- and low-frequency band application. The fabricated PA module can cover any three bands out of five popular high- and low-frequency UMTS bands. To enhance the efficiency during low output power operation, the authors' stage-bypass technique is also employed. The fabricated PA module showed adjacent channel leakage ratios better than -39 dBc up to the rated linear output power and power-added efficiencies of higher than 39% at <I>P</I><SUB>out</SUB>=28 dBm over all the UMTS frequency bands. Efficiency degradation was limited to less than 2% compared to the single-band PA. Measured RF performance of the reconfigurable PA validates the usefulness of the proposed reconfigurable structure for multiband UMTS applications.</P>
A CMOS Stacked-FET Power Amplifier Using PMOS Linearizer with Improved AM-PM
Unha Kim,Jung-Lin Woo,Sunghwan Park,Youngwoo Kwon 한국전자파학회JEES 2014 Journal of Electromagnetic Engineering and Science Vol.14 No.2
A linear stacked field-effect transistor (FET) power amplifier (PA) is implemented using a 0.18-μm silicon-on-insulator CMOS process for W-CDMA handset applications. Phase distortion by the nonlinear gate-source capacitance (Cgs) of the common-source transistor, which is one of the major nonlinear sources for intermodulation distortion, is compensated by employing a PMOS linearizer with improved AM-PM. The linearizer is used at the gate of the driver-stage instead of main-stage transistor, thereby avoiding excessive capacitance loading while compensating the AM-PM distortions of both stages. The fabricated 836.5 MHz linear PA module shows an adjacent channel leakage ratio better than ?40 dBc up to the rated linear output power of 27.1 dBm, and power-added efficiency of 45.6% at 27.1 dBm without digital pre-distortion.
A case of primary cutaneous diffuse large B-cell lymphoma with multifocal subcutaneous lesions
( Dongjoo Kim ),( Sookyung Lee ),( Joongheon Seo ),( Myoungshin Kim ),( Unha Lee ) 대한피부과학회 2016 대한피부과학회 학술발표대회집 Vol.68 No.1
In the WHO-EORTC (World Health Organization-European Organization for Research and Treatment of Cancer) classification, the primary cutaneous B-cell lymphomas were divided into 4 groups. Among them, primary cutaneous diffuse large B-cell lymphoma, leg type (PCLBCL LT) is a very unique entity in that it predominantly affects elderly patients and presents as rapidly progressing nodules or tumors confined to legs or rarely on other body parts. A 82-year-old woman presented with rapidly growing multiple subcutaneous nodules in her both upper eyelid, right chest and back. Microscopic examination of skin biopsy specimen showed diffuse infiltrates of large atypical lymphocytes with vesicular nuclei, prominent nucleoli and moderate degree of mitotic figures in deep dermis and subcutis. They were largely composed of centroblast- and immunoblast-like cells. Immunophenotypic studies revealed the lymphoid infiltrates reacted with CD20, bcl-2 and bcl-6 protein, but none of the sections expressed CD3, CD10, CD30 and Ebstein-Baar Virus in situ hybridization. In physical examination and staging work-up, we could not find any other extracutaneous or systemic involvement. The patient was diagnosed with DLBCL and was treated with 3 cycles of high-dose multiagent chemotherapy with the anti-CD20 monoclonal antibodies. Herein, we report a case of primary cutaneous diffuse large B-cell lymphoma with multifocal skin lesions.
Verruca plana developing after semipermanent tattooing
( Dongjoo Kim ),( Dongyeup Lee ),( Sookyung Lee ),( Myoungshin Kim ),( Unha Lee ),( Jeonghee Hahm ) 대한피부과학회 2015 대한피부과학회 학술발표대회집 Vol.67 No.1
Tattooing for cosmetic adornment is becoming more popular around the world. Yet there are many complications associated with the introduction of pigment into skin, such as local inflammation, allergic reactions and infection. The infectious side effects include local bacterial infections and transmission of hepatitis, syphilis and human immunodeficiency virus (HIV). A 21-year-old healthy man presented with multiple flesh verrucous papules on forearms after undergoing semipermanent tattooing. Histologic examination of the cutaneous lesion showed acanthosis and koilocytosis that are typical of verruca plana. Proliferation of dilated capillaries was present within the papillary dermis. The tattooing had been done 2 years earlier by an amateur. Herein, We report a case of verruca plana that developed after semipermanent tattooing.
A case of subungual amelanotic melanoma
( Hoyoung Kim ),( Jaeho Lee ),( Joongheon Suh ),( Sookyung Lee ),( Unha Lee ),( Myoungshin Kim ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.1
Subungual amelanotic melanoma is rare, only 15-25% of subungual melanoma. Since it appears pinkish or reddish, early diagnosis is often delayed causing poor prognosis. It usually occurs in thumbs or great toes. Pathogenesis of amelanotic melanoma is not well elucidated, but lack of tyrosinase and agenesis of melanosomes are possible causes. A 67-year-old male had subungual erythematous papule on his left thumb. It appeared 10 years ago and had increased in size splitting the nail. At the first visit, the lesion had discharge smelling foul odor. The biopsy specimen of nail plate showed several hyperchromatic large cells in epidermis and nail plate. In immunohistochemistry, Melan-A was focally positive and p63 was negative. The specimen of nail bed showed hyperchromatic and pleomorphic cells with positivity for Melan-A and negativity for pan-cytokeratin. He underwent excisional biopsy and the specimen showed atypical melanocytes in epidermis and nests of numerous hyperchromatic cells with mitotic figures in dermis. He was diagnosed with subungual amelanotic melanoma with pathologic stage T3b.
A case of pigmented spindle cell nevus with an unusual dermoscopic feature
( Dongjoo Kim ),( Dongyeup Lee ),( Sookyung Lee ),( Myoungshin Kim ),( Unha Lee ),( Jeonghee Hahm ) 대한피부과학회 2015 대한피부과학회 학술발표대회집 Vol.67 No.1
Pigmented spindle cell nevus (PSCN, Reed nevus) is a solitary heavily pigmented macule or papule that usuallyoccurs on the lower legs of women in the second decade of life. Histologically, fascicles of uniform, elongated, pigmented nevoid cells at the dermo-epidermal junction tend to fuse with neighboring nests. Three main dermoscopic patterns of PSCN are starburst, globular, atypical pattern. Also, very few cases of PSCN with peripheral reticular pattern have been reported. Our patient was a 49-year old female presented with a 1-year history of black ovoid papule on the right second finger. Dermoscopic examination of the lesion showed a brown to black diffuse pigmentation with discrete depigmentations in the center of the lesion. At the periphery of the lesion, the streaks radiated in the direction of the normal skin, forming a relatively uniform network, characteristic of “peripheral reticular” dermoscopic pattern. Histopathologic examination revealed the typical histologic features of PSCN. There was no atypical feature such as mitoses or pleomorphism. Herein, we report a case of pigmentedspindle cell nevus with the unusual dermoscopic feature.