Exam2SolutionsSummer2001

Exam2SolutionsSummer2001 - ECE 3040B Microelectronic...

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Unformatted text preview: ECE 3040B Microelectronic Circuits Exam 2 July 3, 2001 Dr. W. Alan Doolittle I Print your name clearly and largely: go In +lah s Instructions: Read all the problems carefully and thoroughly before you begin working. You are allowed to use 1 new sheet of notes (1 page from and back), your note sheet from the previous exam as well as a calculator. There are 100 total points in this exam. Observe the point value of each problem and allocate your time accordingly. SHOW ALL WORK AND CIRCLE YOUR FINAL ANSWER WITH THE PROPER UNITS INDICATED. Write legibly. IfI can not read it, it will be considered to be a wrong answer. Do all work on the paper provided. Turn in all scratch paper, even if it did not lead to an answer. Report any and all ethics violations to the instructor. Good luck! Sign your name on ONE of the two following cases: I DID NOT observe any ethical violations during this exam: I observed an ethical violation during this exam: __._____._._____________________ First 25% Multiple Choice (Select the most correct answer) 1.) (5-points) When analyzing a circuit using the ideal diode model, which of the following is -—' e: m The diode is replaced with either an open or a short circuit . The diode is replaced with a battery plus an open or short circuit 0.) The diode has a small non-zero leakage current flowing in reverse bias d.) The diode has an offset voltage equal to the built in voltage of the diode e.) None of the above. 2.) (5-points) The emitter injection efficiency, 7. .. a.) ...characterizes the ability of a diode to handle large currents. b.) . . .characterizes the ability of a transistor to handle large currents. c.) characterizes the percentage of minority carriers in the base that make it to the collector. , . .. characterizes how effectively the emitter can inject can-iers into the base A. characterizes how effectively the collector can inject carriers into the base 3.) (S-points) Which of the following bias diagrams is consistent with reverse bias (all three diagrams must be correct, i.e. the schematic symbols, energy band diagrams and the material drang must have the correct polarity)? b.) 4.) (5-points) Ifwe want to bias this transistor into forward activ ode, which of the following is true? 3.>v2>v1 . V1>V2>V3 c.) V2>V1>V3 d.) V1>V3>V2 e.) You cannot bias a transistor without resistors. 5.) (S—points) If we want to bias this transistor into cutoff, which of the following is true? a. V3>V1 and V1>V3 b. V1>V2 and V3>V2 V2>V3 and V1>V3 a v2>v1 and V2>V3 e. You cannot bias a transistor without resistors. Second 15% Short Answer and Fill in the blank: 6.) (3-points each, 15 points total) The (a.) g m .‘ + jfi r ofa BJT biased into forward active mode is (b. circle one) oped and is responsible for injecting it’s majority can'iers into the (c.) a e where they diffuse to the (d.) C 0 ' 'QL 1‘0 ’- and are “collected” by a large (c.) Q (go-Wk. 'Fz'el 0/ . as Oarki Third 20% 7.) (20-points total in two parts) A GaAs p+ n diode has the following parameters: Intrinsic concentration ni= 2e6 cm'3 Relative dielectric constant, K, (or 6,)=l3.1 Area=256um2(16umx 16um) 0‘ Minority carrier diffusion coefficient, DP, in the p side of 5 cm2/Sec Vout Minority carrier diffusion length, LP, in the p-side of 0.1 um p-type doping of 1e19 cm'3 R Minority carrier diffusion coefficient, 1),, in the 11 side of 10 cm2/Sec 1E6 ohm; Minority carrier diffusion length, L.., in the n-side of 0.5 urn n-type doping of 1e15 cm'3. - if, The diode is to be used as a photodetector biased with the circuit shown. Find the value of the output voltage, Vout, for (a. lO-points) dark conditions where there is no light and (b. 10—points) for lighted conditions when a generation rate of 1e19 electron-hole Pairs/cm3-Second illuminates the diode. \I/moa 5% ‘> I": I0 601+ Glear‘y 09— Can aniy be reverse bo'aseo/ 50/ g - u+= —IR, I: A2153. 0 2:}. a? LhN&+-—EE—No ': ‘68—“ (0.0016 cm x 0.00“ CM)< R 2 6("3/5 chéZcm'é , i Mag/S 366) ea," $3.50“ '6 l1 “'3 , Extra work can be done here, but clearly indicate with problem you are solving. 1 LgfiA‘F‘n :r:t Ia’cvk +ILIS/xr : {[0 —c;,4 (La +W+Lp)€t / W -~ 1 k; 69 N +No 1 ’30 Mo) (Vb' - VA) V“ 1%: A (“:3”) 2 (Bl) 9.8541- W F/cM 'leHHeI 63:”) W: [3,€6AM> _ I 50 I: ~Io " 1.66""('00")1(le-5‘m+3“9‘94 + 58-76M) 36W cad/5 = - L33 9—“) v0u+ '2 *I R\ (4In Section - 40%) Pulling all the concepts together for a usefill purpose: 8.) (40-points) Given the following “video amplifier circuit” and BJT Parameters, what is the AC voltage gain, VoutACNinAC? Assume: BDC=100, Early voltage is infinite, turn on voltages for all forward biased junctions are 0.6 V. You may assume all capacitors are very large values and are thus, AC shorts. Additionally consider the circuit to be operated at low frequencies where you can neglect all small signal capacitances. Also, neglect all resistances that result from quasi-neutral regions. ‘er alwa’es {an +kis circuit"? affi exemfiefi } @‘r over-yv‘alrase |n€tl§ fratccwdh a; we disc“ 54w! in 6 iaés, 0‘: V+k ire ILA“: VBE — IE R7 (5" IEK... £576] 2 I9 (new) + 0,6 —— (IJOH)I5 (Mr [M L5 ' _ ,4 — W _ . I3 - Hausa, Iowans) '50. 44 Extra work can be done here, but clearly indicatc with problem you are solving. vc 2 5—— L R5— V 2 5-4‘W665Q63) 3AM V If (at; +K7) =<l.6Ie-3) (was) Pat‘wa ACiV'Ve 0, ,‘5 01670 filthce C- 0416 fl‘KCC V5 70V y'alvf 2 0,00% 5 (o) Fw= “£7: " (71%;: MM HZ w my wives : .05}: Do 94=IDJTIS = iii—IE" '9 r4: 55—: .00 «'9 (of/86+ a éfanyhdh. [ % g 4.(. Extra work can be done here, but clearly indicate with problem you are solving. 56 {M4505 1 \n) Man-r: A%’ 7M (,Léc’f'. MAH’8551/ 3) g ’ 60"¢V/VR3”R1 ' ’U'i'k 1‘ firth ___.———- RBNR1+R5 WK ‘ Rblma | \ ’Wn ' m C. (Eek. um? less V = 0-417 V/V (c) Extra work can be done here, but clearly indicate with problem you are solving. 1/9th : 0.38%? V/V. <1) 4” Q— 50.3)(a.am) 0"”7) Av: "171.? v/y Bonus of 15 points total: In the last problem, what is the minimum and maximum “Large signal” output swing possible before distortion begins? Note: I am asking for the “actual” voltage swing, not the simpler “worst case” voltage swing. 45V «W V; '3' K1 5V: Isa? +0.7 +Ic fir Lit-3V: '05:) R7 + R5) Ia 1;: we: w" Va: EV‘ 14/85" Vt - 0.306 V ...
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This note was uploaded on 05/26/2010 for the course ECE 3025 taught by Professor Citrin during the Spring '08 term at Georgia Tech.

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Exam2SolutionsSummer2001 - ECE 3040B Microelectronic...

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