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The design, construction, and results of evaluation of an animal-exposure system for the study of biological effects of extremely low frequency (ELF) magnetic fields are described. The system uses a square coil arrangement based on a modification of the Helmholtz coil. Due to the cubic configuration of this exposure system, horizontal and vertical magnetic fields as high as 0.3 mT can be generated. Circularly polarized magnetic fields can also be generated by changing the current and phase difference between two sets of coils. Tests were made for uniformity of the magnetic field, stray fields, sham-exposure ratio of stray field, changes of temperature and humidity, light intensity and distribution inside the animal-housing space, and noise due to air-conditioning equipment. Variation of the magnetic field was less than 2% inside the animal housing. The stray-field level inside the sham-exposure system is less than 2% of experimental exposure levels. The system can be used for simultaneous exposure of 48 rats (2 to a cage) or 96 mice (4 to a cage).

Noise sources of 70-nm NMOS transistors the model by presenting a noise parameter simulation of were extracted to reveal the channel noise is dominant up to MOS transistors. 26 GHz. Gate induced noise increased in proportion to , however, its level was 1 to 2 orders of magnitude lower than II. NOISE PARAMETER MEASUREMENT the channel noise. A new approach to accurately capturing In this study, ATN NP-5 (from 0.5 to 6 GHz) and the behavior of thermal noise by compensating for the Maury ATS (from 4 to 26 GHz) systems were used for discrepancy between extracted and simulated channel noise noise parameter (NFmin, Rn, Fopt) measurement. NMOS through the addition of an excess noise source was l-, , Xdemonstrated. The excess noise source was incorporated into transistors with physical gate lengths of 70 nm and fixed our RFMOS model, which enabled us to accurately simulate finger width of 2.5 pm were characterized by the systems. noise parameters. By using this technique the noise figure ofThe total gate width, Wtotai, was varied from 10 to 160 ptm.

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