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FUTURE SPACE INFRARED TELESCOPE MISSION, SPICA
MATSUMOTO TOSHIO The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.2
SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an infrared astronomical satellite with a 3.5 m cooled telescope which is very powerful in mid- and far- infrared observations and makes complementary role to JWST and Herschel. SPICA will be launched at ambient temperature without any cryogen into the Sun-Earth L2 orbit and cooled down in space to 4.5 K with use of efficient radiative cooling and mechanical coolers. The present status of SPICA and the developments of the satellite system are reported.
MATSUMOTO TOSHIO The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.2
ASTRO-F is the first Japanese dedicated infrared astronomical satellite which will be launched in 2005FY and is now in the final stage of the development. ASTRO-F is a 70 cm aperture cryogenically cooled telescope and designed for the infrared survey with much higher sensitivity and angular resolution than IRAS. We present the current status of the mission, focal plane instruments, and the observation plan now being discussed.
A Method to Improve Linearity of a Variable Operating Range Transconductor
Toshio Miyazawa,Fujihiko Matsumoto,Kazufumi Kanegae,Yasuaki Noguchi 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
A transconductor using bias offset technique is known as a linear MOS transconductor. The linearity is deteriorated by nonideal factors. Major deterioration is caused by mobility degradation from an effect of vertical field. This paper proposes a linearization technique of the MOS transconductor following change of operating range. This technique improves the linearity of transconductance characteristic by adding two MOSFETs operating as resistors and a source follower to the conventional circuit.
An NIC Voltage Divider for a Linear Transconductor
Fujihiko Matsumoto,Takeshi Sonoda,Toshio Miyazawa,Shintaro Nakamura,Yasuaki Noguchi 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
A local feedback linear transconductor requires a voltage divider. For realization of a gyrator-C filter, an output terminal of a transconductor in the filter is connected to an input terminal of itself or another transconductor owing to local feedback of gyrators and equivalent resistors. If NIC circuits are employed in a gyrator-C filter, the voltage divider and the NIC are connected in parallel. This paper proposes a NIC divider that has two roles: one is a voltage divider and the other is an NIC for improvement of the output resistance of a transconductor.
A Level Shifter for a Bias-Offset Transconductor
Fujihiko Matsumoto,Toshio Miyazawa,Shintaro Nakamura,Yasuaki Noguchi 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
A transconductor is a fundamental building block for analog signal processing circuits, such as filters and multipliers. For such applications, the transfer characteristic of the transconductor is desired to be linear. The bias-offset transconductor is known as a linear MOS transconductor. The transconductor has floating voltage sources. This paper presents a new design of the floating voltage source. If the proposed circuit is used as a level shifter for the linear transconductor, the output DC voltage is more accurate than that of the conventional circuit. Further, the proposed circuit is used as the second signal voltage source for a multiplier, the second harmonic distortion is improved. Simulation results show those advantages.