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Unformatted text preview: Question 1 A Si nchannel MOSFET has V G =3.0V, and V D =8V. The parameters for the MOSFET are Z=5 m, L=1.5 m, N a =10 16 /cm 3 , r =3.9, oxide thickness 70, the effective interface charge Q i is 9X10 10 qC/cm 2 , and a surface mobility of n =200cm 2 /Vs. Calculate the drain current for the transistor assuming V T = 0.2V. V D >(V GV T ) so the FET is saturated, and ( ) ( ) ( ) ( ) ( ) ( ) 2 4 8 14 2 A/V 10 29 . 3 cm 10 70 1.5 F/cm 10 85 . 8 9 . 3 2 5 Vs / cm 200 = = = = d L Z L ZC k i n i n n () ( ) ( ) ( ) ( ) ( ) ( ) 1.68mA A 00168 . .2V 3 A/V 10 64 . 1 V 2 . 3 2 A/V 10 29 . 3 2 sat 2 2 4 2 2 4 2 = = = = = T G n D V V k I Question 2 For the MOSFET in question 1, calculate the actual V T for the transistor. For an nchannel, p Si transistor with N a =10 16 /cm 3 V 96 . = ms The effective interface charge Q i is: ( ) ( ) 28192 10 i C/cm 10 44 . 1 C 10 1.6 cm 10 9 Q = = () ( ) 2 7 o 8 o 14 i F/cm 10 93 . 4 A cm/ 10 A 70 F/cm 10 85 . 8 9 . 3 C = = = d i The insulator capacitance: Finding F ( ) V 347 . 10 5 . 1 10 1 ln V 0259 . ln 10 16 = = = i a F N N q kT ( ) ( ) ( ) ( ) ( ) ( ) 2 8 3 16 19 14 C/cm 10 82 . 4 347 . cm 10 C 10 6 . 1 F/cm 10 85 . 8 8 . 11 2 2 2 2 1 2 1 2 1...
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 Spring '08
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