Title :
Cohn filters for minimizing thermal noise of Class A amplifiers
Author :
Girgis, Girgis A. ; Holdmann, Michael M. ; Rizkalla, Maher E. ; Gundrum, Harry C.
Author_Institution :
Dept. of Electr. Technol., Nebraska Univ., Omaha, NE, USA
Abstract :
A Cohn filter circuit was designed to bypass the white noise generated by the thermal properties of a 150-W, 300-MHz class-A amplifier. The optimum values of the network components were derived, and the effects of harmonic distortion and noise were analyzed. A circuit has been developed for use in a system for magnetic resonance spectroscopy. The circuit was designed to reduce the thermal noise floor of the amplifier, measured at 200 μW (between pulses), by ≈40 dbs
Keywords :
harmonics; magnetic resonance spectrometers; passive filters; radiofrequency amplifiers; spectrometer components and accessories; thermal noise; white noise; 150 W; 300 MHz; Class A amplifiers; Cohn filter circuit; harmonic distortion; magnetic resonance spectroscopy; network components; noise floor; thermal noise; white noise; Circuit noise; Filters; Harmonic analysis; Harmonic distortion; Magnetic analysis; Magnetic noise; Magnetic separation; Pulse amplifiers; Pulse measurements; White noise;
Conference_Titel :
Circuits and Systems, 1991., Proceedings of the 34th Midwest Symposium on
Conference_Location :
Monterey, CA
Print_ISBN :
0-7803-0620-1
DOI :
10.1109/MWSCAS.1991.252077
