B johnson thermal agitation of electricity in

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Unformatted text preview: in bandwidth B delivered to a matched load – Example: B = 1Hz PN = 4 x 10-21W = -174 dBm – Reference: J.B. Johnson, “Thermal Agitation of Electricity in conductors,” Phys. Rev., pp. 97-109, July 1928. EECS 240 Lecture 5: Noise © 2006 A. M. Niknejad and B. Boser 5 Resistor Noise Model Noisy resistor model R PN R vn 2 vn PN = k BTB = 4R Mean square noise voltage: 2 vn = 4k BTRB EECS 240 Lecture 5: Noise © 2006 A. M. Niknejad and B. Boser 6 Thermal Noise • • • Present in all dissipative elements (resistors) Independent of DC current flow Random fluctuations of v(t) or i(t) – – – – Instantaneous noise is unpredictable Result of many random, superimposed collisions Relaxation time constant τ ~ 0.17ps Consequences: 2 vn = 4k BTRB • Zero mean • G...
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