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Unformatted text preview: ndependent of temperature Example:
ID = 1mA, B = 1MHz i = 2qI D ∆f
n 17nA rms Shot noise versus thermal noise (rd = Vt/ID)
Thermal equilibrium EECS 240 Lecture 5: Noise © 2006 A. M. Niknejad and B. Boser 9 BJT Noise
vb = 4k BTrb ∆f ∆f
i = 2qI B ∆f + K1 I B
b α ic2 = 2qI C ∆f • The collector and base shot noise are partially correlated.
• The base resistance contributes thermal noise.
• Note that ro does not contribute noise. It’s not a physical
EECS 240 Lecture 5: Noise © 2006 A. M. Niknejad and B. Boser 10 FET Noise
• In addition to the extrinsic physical resistances in
a FET (rg, rs, rd), the channel resistance also
contributes thermal noise.
• The channel conductance is calculated by • The noise injection is a distributed process. The
net sum of the noise injection gives (note γ) EECS 240 Lecture 5: Noise © 2006 A. M. Niknejad and B. Boser 11 More Fundamental Expres...
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