Tomoyuki Asada
Mitsubishi Electric
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Publication
Featured researches published by Tomoyuki Asada.
european microwave conference | 1999
Kazutomi Mori; Kenichirou Choumei; Teruyuki Shimura; Tomoyuki Asada; Toshio Okuda; Kazuya Yamamoto; Takeshi Miura; Ryo Hattori; T. Takagi; Yukio Ikeda
A GSM900/1800 Dual-Band AlGaAs/GaAs HBT(Hetero-junction Bipolar Transistor) MMIC power amplifier has been developed. It includes power amplifiers for GSM900 and DCS1800, constant voltage bias circuits and d.c. switch. A novel multi-finger HBT layout which can realize uniform output load impedance and thermal distribution of each HBT finger are applied to the final-stage HBT in order to achieve high efficiency. The developed MMIC amplifier has provided output power of 34.5dBm and power-added efficiency of 53.4% for GSM900, and output power of 32.0dBm and power-added efficiency of 41.8% for DCS1800.
IEICE Transactions on Electronics | 2005
Teruyuki Shimura; Tomoyuki Asada; Satoshi Suzuki; Takeshi Miura; Jun Otsuji; Ryo Hattori; Yukio Miyazaki; Kazuya Yamamoto; Akira Inoue
This paper describes a 3.5V operation InGaP HBT MMIC power amplifier module for use in GSM/EDGE dual-mode, 900/1800/1900 MHz triple band handset applications. Conventional GSM amplifiers have a high linear gain of 40 dB or more to realize efficiency operation in large gain compression state exceeding at least 5 dB. On the other hand, an EDGE amplifier needs a linear operation to prevent signal distortion. This means that a high linear gain amplifier cannot be applied to the EDGE amplifier, because the high gain leads to the high noise power in the receive band (Rx-noise). In order to solve this problem, we have changed the linear gain of the amplifier between GSM and EDGE mode. In EDGE mode, the stage number of the amplifier changes from three to two. To reduce a high gain, the first stage transistors in the amplifier is bypassed through the diode switches. This newly proposed bypass circuit enables a high gain in GSM mode and a low gain in EDGE, thus allowing the amplifier to operate with high efficiency in both modes while satisfying the Rx-noise specification. In conclusion, with diode switches and a band select switch built on the MMIC, the module delivers a P out of 35.5 dBm and a PAE of about 50% for GSM900, a 33.4 dBm P out and a 45% PAE for GSM1800/1900. While satisfying an error vector magnitude (EVM) of less than 4% and a receive-band noise power of less than -85dBm/100kHz, the module also delivers a 29.5 dBm P out and a PAE of over 25% for EDGE900, a 28.5 dBm P our and a PAE of over 25% for EDGE 1800/1900.
european microwave conference | 1999
Satoshi Suzuki; Kazuya Yamamoto; Tomoyuki Asada; Kenichiro Choumei; Akira Inoue; Ryo Hattori; N. Yoshida; Teruyuki Shimura
This paper describes a burnout mechanism in high power KBT under mismatching load conditions. Experimental and analytical investigations reveal that the burnout of the HBT is caused by a large amount of base current resulting from avalanche breakdown in a collector-base junction, especially in the case of constant base voltage drive usually employed in high power operation. Based on the investigation, an active feedback circuit is newly proposed to prevent the catastrophic failure, and then the effectiveness of the circuit was successfully confirmed by simulation and experiments.
Archive | 2006
Kazuya Yamamoto; Tomoyuki Asada; Hiroyuki Otsuka; Kosei Maemura
Archive | 2010
Takayuki Matsuzuka; Kazuya Yamamoto; Tomoyuki Asada
Archive | 2010
Kazuya Yamamoto; Tomoyuki Asada; Miyo Miyashita
Archive | 2006
Kazuya Yamamoto; Tomoyuki Asada
Archive | 1999
Tomoyuki Asada; Akira Inoue; Satoshi Suzuki; Kazuya Yamamoto; 晃 井上; 和也 山本; 智之 浅田; 敏 鈴木
Archive | 2005
Tomoyuki Asada; Kazuya Yamamoto; 和也 山本; 智之 浅田
Archive | 2007
Kazuya Yamamoto; Tomoyuki Asada; Hiroyuki Otsuka; Kosei Maemura