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A CMOS LNA based on Inverter Structure for Wideband Applications
정지학 한국지식정보기술학회 2019 한국지식정보기술학회 논문지 Vol.14 No.3
In recent years, the potential technology for short distance and high-data wireless communication systems has been grown. Ultra-wideband (UWB) technology has emerged as a considerable interest and new technology. According to a proposed standard, the UWB system is assigned to operate over 3.1 - 5 GHz or 3.1 - 10.6 GHz. Most of the proposed applications allow transmission of signals between 3.1 and 10.6 GHz. In this paper, a wideband CMOS Low Noise Amplifier (LNA) is proposed with a inverter structure using inductor peaking technique and broadband matching techniques, which meets stringent requirements of UWB system in the proposed specifications. The proposed LNA has the inverter structure and cascode structure with shunt feedback. Measurement results show the maximum power gain (S21) of 17.4 dB with the 3-dB band and input/output reflection coefficient (S11, S22) of less than –9.7 dB from 3.1 to 9.6 GHz. In addition, the fabricated LNA achieves the minimum noise figure (NF) of 3.5 dB from the operating frequency, which value is much lower than previously reported state-of-the-art wideband amplifiers. The input-referred IIP3 and the input-referred P1dB of the proposed LNA are achieved as 0 dBm and –10 dBm, respectively, while consuming 27 mW in 0.18- RF CMOS process.
정지학,이관구,오세익,우명룡,조성중 대한산부인과학회 1997 Obstetrics & Gynecology Science Vol.40 No.10
Cerebrovascular accidents are an important indirect obstetric cause of maternal morbi-dity and mortality. The incidences, causes, and prognosis of nonhemorhagic strokes occurr-ing in association with pregnancy or puerperium are poorly understood. Cerebral venous thrombosis is an uncommon form of cerebrovascular disease. But pregnancy, especially pu-erperium is predisposing events of cerebral venous thrombosis. The overall average mortal-ity of pregnant patients with cerebral venous thrombosis is approximately 30%. An aggre-ssive work-up to define the etiology of stroke in pregnancy or puerperium is necessary in order to implement cause-specific management with subsequent reduction in morbidity and mortality.
정지학,양관철,박영권,강재열 대한산부인과학회 1994 Obstetrics & Gynecology Science Vol.37 No.7
저자는 본 병원 산부인과에서 태아경부 수활액 낭종 1례를 경험하였기에 이에 대한 간단한 문헌적 고찰과 함께 보고하는 바이다. This is a case report of a large bilateral cystic hygroma in a fetus that was suspected by ultrasonography and was confirmed by postpartum examination. Fetal cystic hygromas are congenital malformations of the lymphatic system appearing as single or multilobulated fluid-filled cavities, most often about the neck. The cyst walls are lined with a single layer of flattened endothelium supported by a connected tissue stroma. The fluid within the cyst is serous, being clear or straw-colored and occasionally blood-stained. They are believed to arise from the failure of lymphatic system to communicate with the venous system in the neck. They often progress to hydrops and cause fetal death. The mother was a 26 years old multigravida and denied any exposure to infection or drugs during the gestation. The baby was induced after the 18 weeks gestation and the fetus weight was 1 pound.
저전력 BLE/ZigBee IoT MCU 용 RF transciever 설계 연구
정지학,김응주 한국지식정보기술학회 2020 한국지식정보기술학회 논문지 Vol.15 No.1
Recently, the demand of BLE/ZigBee IoT MCU is highly increased for low power sensor network realization. In this paper, a low power and low cost BLE/ZigBee RF transceiver is studied with careful review of Bluetooth 5.0 core specification for BLE and IEEE 802.15.4 ZigBee specification. For the receiver side, a low-IF architecture with digital filtering and high ADC dynamic range is used to eliminate the analog filter to achieve both of small size and low power consumption simultaneously. Thanks to the inherent characteristics of a low-IF receiver, the proposed architecture also has the merits of high performance because of no signal loss due to DC offset removal filter and no flicker noise. For the transmitter side, a direct frequency modulation based on two point modulation and gain and phase mismatch calibration is proposed also for low power consumption. Moreover, 5bit binary-weighted inverse class-F power amplifier is proposed because the inverse class-F power amplifier shows greatly improved power efficiency even better than that of the class-F power amplifier. The 5bit binary-weighting is used for maximum transmit output power control as well as transmitter ramping for on-to-off and off-to-on transition. To meet FCC spurious emission regulation, on-chip and off-chip LC filtering and LO duty ratio control to suppress 3rd harmonic and 2nd harmonic, respectively. Finally, this paper presents the power architecture, which can support battery operation and solid power supply operation for best power efficiency and BOM cost optimization.
정지학, 정회경 배재대학교 공학연구소 2021 공학논문집 Vol.23 No.1
In this thesis, in order to supplement the problems of the existing household chemical product information service, Green Nuri service, distributed household chemical product information, ingredient information, and hazardous and risk information of chemical ingredients were collected and integrated into a database, and images collected separately. We propose a more convenient and real life chemical product information provision service platform configuration by realizing the function of recognizing and searching for household chemical products. Through the implemented services, a successful and efficient service development using public data is presented, and by providing correct and accurate information on household chemical products to users, a successful I look forward to becoming an example. 본 논문에서는 기존의 생활화학제품 정보제공 서비스인 초록누리 서비스의 정보 이원화와 편의성에 대한 문제점을 보완하고자 분산되어있는 생활화학제품정보와 성분정보, 화학성분의 유해·위험성 정보를 수집하여 데이터베이스에 통합하고, 별도로 수집된 이미지를 통해 생활화학제품을 인식하고 검색 할 수 있는 기능을 구현하여, 보다 편리하고 실생활에 맞는 생활화학제품 정보제공 서비스 플랫폼 구성을 제안한다. 구현된 서비스를 통하여, 공공데이터를 이용한 효율적인 서비스 개발 방향을 제시하고, 이용자에게 생활화학제품에 대한 올바르고 정확한 정보를 제공함으로써 안전하게 생활화학제품 사용을 할 수 있도록 도와주는 성공적인 사례가 되기를 기대한다.