Title :
Application of null networks in minimizing thermal noise of Class A power amplifiers
Author :
Holdmann, Michael M. ; Girgis, Girgis A. ; Rizkalla, Maher E.
Author_Institution :
Lilly Res. Lab., Indianapolis, IN, USA
Abstract :
A filter circuit is described which was designed to shunt 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 analytically in order to obtain maximum signal-to-noise ratio at the operating frequency. The effects of harmonic distortion and noise were analyzed. A circuit has been modeled for use in a system for magnetic resonance spectroscopy. In this simulation, a 200 μW thermal noise amplitude between pulses of 180-MHz sinewaves was reduced by ≈40 dB
Keywords :
harmonics; power amplifiers; thermal noise; 150 W; 180 MHz; 200 muW; 300 MHz; Class A power amplifiers; filter circuit; harmonic distortion; magnetic resonance spectroscopy; null networks; signal-to-noise ratio; thermal noise; white noise; Circuit noise; Filters; Frequency; Harmonic distortion; Magnetic analysis; Magnetic noise; Noise generators; Signal analysis; Signal to noise ratio; White noise;
Conference_Titel :
Circuits and Systems, 1990., Proceedings of the 33rd Midwest Symposium on
Conference_Location :
Calgary, Alta.
Print_ISBN :
0-7803-0081-5
DOI :
10.1109/MWSCAS.1990.140700
