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Unformatted text preview: noise (strong inversion)
– Drain current (use gds0 not gm)
γ = 2/3 for small fields (long L)
can be 1-2 or even larger for short L • Since the expression with gm is convenient for input referred
noise calculations, it is often used. The expression with gds0 is
more accurate and should be used. The factor α captures the drop
in gm for a short channel device.
• Gate induced noise (142/242 topic)
• Gate current (leakage shot noise)
• No noise from ro (not physical resistor)
• Extrinsic noise sources (drain/source/gate resistance)
EECS 240 Lecture 5: Noise © 2006 A. M. Niknejad and B. Boser 15 FET Noise Model • The resistance of the substrate also generates
thermal noise. In most circuits we will be
concerned with the noise due to the channel
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