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Design and Implementation of 40-GHz-Band LNA MMICs with Super Low-Gain Flatness
Jin-HeeLee,Hyung-SupYoon,JaeYeobShim,Kyung-HoLee 한국물리학회 2002 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.40 No.4
This paper introduces the design and implementation of 40-GHz-band 4-stage/2-stage low-noise amplier with low-gain atness for wide-band wireless multimedia and satellite communication systems. The 40-GHz-band 4-stage MMIC demonstrate a small signal gain of more than 20 dB, an input return loss of 10.2 dB, and an output return loss of 21.8 dB for 4042 GHz. The gain atness of the 40-GHz-band 4-stage LNA was 0.1 dB for 4042 GHz. The noise gure of the 40 GHz-band 4-stage LNA was simulated to be less than 3.2 dB for 4042 GHz. While the 40-GHz-band 2-stage LNA MMIC demonstrate a small signal gain of more than 10.5 dB, an input return loss of 8.6 dB, and an output return loss of 19.8 dB for 4042 GHz. The gain atness of the 40-GHz-band 2-stage LNA was 0.4 dB for 4042 GHz. The noise gure of the 40-GHz-band 2-stage LNA was simulated to be less than 3.0 dB for 4042 GHz. The chip size of the 2-stage and the 4-stage LNA MMICs were 2.11.7 mm2 and 3.71.7 mm2, respectively.
Current Dispersion E ects of Planar-Type AlGaN/GaN HFET's Grown by MOCVD
Chang-SeokKim,Jin-SikYun,Byung-KwonChoi,Jae-EungOh,Sung-BumBae,Jung-HeeLee,Jong-WookKim,Jae-SeungLee,Jin-HoShin 한국물리학회 2002 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.40 No.2
Low frequency-transconductance dispersion and pulsed I-V measurements have been taken on a planar-type an AlGaN/GaN heterostructure field-effect transistor (HFET) to study the effect of trap states on its current-voltage (I-V) characteristics. The transconductance as a function of frequency ranging from 1 Hz to 100 kHz was measured at various temperatures and bias conditions. We have observed the existence of electron traps associated with the surface states or bulk traps. These electron traps are responsible for the decrease of the transconductance and the drain current collapse. From the Arrhenius plot, a relatively slow state with an activation energy of 47.2 meV has been identified. To expect microwave power performance of the device, the pulsed I-V characteristic was measured in dierent class operations. A model to explain the observed current collapse has been suggested.