M niknejad and b boser 9 bjt noise 2 vb 4k btrb f f i

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Unformatted text preview: ndependent of temperature Example: ID = 1mA, B = 1MHz i = 2qI D ∆f 2 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 2 vb = 4k BTrb ∆f ∆f i = 2qI B ∆f + K1 I B f 2 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 resistor. 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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