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1of8 Microelectronic Devices and Circuits- EECS105 Second Midterm Exam Wednesday, April 16, 2003 Costas J. Spanos University of California at Be College of Engineering Department of Electrical Engineering and Computer Sciences Your Name: _O{ficial Solariou's (last) firs) Your Signature: 1, Print and sign yoy name on this page before you start. 2. You gre allowed two, 85" x11” handwritten sheet, No books or notes! 3. A correct expression is worth 70% of the credit, The calvulution gets you the rest. 4. You have until 4/25/03 to bring any grasting issues to Prof. Spanos’ attention. ww Problem I _ £48 Problem 2 116 Problem 3 116 Problem 4 120 TOTAL f=? _o216 /100 MOS Device Data! (you may not have to use all of these...) bnCox= SOPANV, tpCon= 25HA/V2, Vip = “Wap = 1, Limin = 2m, Vas = 0. ‘dq Ay =0.1V"' when L = pm, and itis otherwise proportional to 1/L_ Cop=2.38F um’, Cin = O.LEF/ur?, Cip= 0.3EF/jumn?, Chom = 0.58/03, Cysup= 0.35fF/am, Com = 0.51F/um, Corp 0.51F/ um BIT Device Data’ (you may not have to use all of these...) Br=Bo=100, Is=10°7A, Vee sar=0.1V, Wa=25V, te=50ps, C= 1SFEVne=0.7V, Cp=10F@Vec=2.0V "Except as indicated om the particular problem... 2o0f8 Problem 1 of 4: Answer each question briefly and clearly. (6 pts each, 48 total) LL What are the nppical values of Rin, Rox for a decent CC voltage buffer? ko nD Cay 6 (Hf) Rin 5-100 100-1000 10-20 kQ Rout 5-109 100-1000 2 100-TKQ =1-10M2 Ff # 409-1000 Vomt 1.2 Why is it important to make the base of a BJT as short as possible? (choose one) 3 So that the transistor occupies less space a So that there are no ohmic losses in the base So that almost all injected minority carriers make it across So that holes and electrons stay uniformly distributed a The transonductance drops in value in value WY Ther, drops in value a The Early voltage gets delayed Provide a brief explanation of the mechanism responsible for the above. Base wich modulation due te the CB doplettan , wylew nghiay the base Guia shaver (derreases \V4l) 1.4 What happens when the channel of a MOSEET is very long? (choose one) The transconductance increases @ Velocity saturation kicks in a The transistor gets too hot JX Ther, increases in value Provide a brief explanation of the mechanism responsible for the above: Choanel Coarsh rradelarion i Leis oF + problem fr Lowy Cinasisters (derreases )) 
