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Unformatted text preview: UNIVERSITY OF CALIFORNIA AT BERKELEY College of Engineering Department of Electrical Engineering and Computer Sciences Homework #10 Solutions Due Tuesday, November 6, 2007 EE 105 Fall 2007 Prof. Liu Problem 1. MOSFET Body Effect a) V TH = V TH + γ parenleftBig radicalbig 2 φ B + V SB − radicalbig 2 φ B parenrightBig V TH = 0 . 5 V V TH = V FB + 2 φ B + 1 C ox radicalbig 2 qǫ s N A 2 φ B φ B = (60 mV)log ( N A /n i ) = 480 mV C ox = ǫ ox /t ox = 1 . 38 μ F / cm 2 V TH = 0 . 362 V γ = 1 C ox radicalbig 2 qN A ǫ s = 0 . 410 V SB = . 773 V b) Reverse biasing the body-source PN junction would increase the short-channel effect. By reverse biasing the body-source junction, the reverse-bias on the body-drain junction is also increased. Thus, reverse body biasing exacerbates the “short channel effect” of | V TH | re- duction with decreasing L , because the depletion charge supported by the source and drain junctions is increased (hence the depletion charge supported by the gate is decreased signifi-...
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- Fall '07
- Electrical Engineering