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Thermal Agitation Noise

August 20th Fact-of-the-Day

Noise voltages due to thermal agitation in resistors set limits on the smallest signal voltages that can be amplified without being lost in noise. Those limits are independent of frequency and are dependant only upon temperature, resistance and bandwidth. At a temperature of 300 degrees Kelvin, an rms thermal agitation noise voltage of 6.4 microvolts develops across a 1/2 megohm resistor for a frequency bandwidth of 5 kHz. ©2004 Martek International All rights reserved.


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