EE 105 - Fall 2009 - Salahuddin - Midterm 2 (solution)

EE 105 - Fall 2009 - Salahuddin - Midterm 2 (solution) -...

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Unformatted text preview: UNIVERSITY OF CALIFORNIA, BERKELEY College of Engineering Department of Electrical Engineering and Computer Sciences BB 105: Microelectronic Devices and Circuits Fall 2009 MIDTERM EXAMINATION #2 10/29/2009 Time allotted: 75 minutes NAME: STUDENT ID#: INSTRUCTIONS: 1. SHOW YOUR WORK. (Make your methods clear to the grader!) 2. Clearly mark (underline or box) your answers. 3. Specify the units on answers whenever appropriate. 4. Unless specified otherwise, include EARLY effect in your analysis. SCORE:} [16 2 [16 3 / 18 Total / 50 PHYSICAL CONSTANTS Description Smbol Value Electronic charge q 1.6><10‘19 C Boltzmann’s constant k 8.62x10'5 eV/K Thermal voltage at VT = 0.026 V 300K kT/q USEFUL NUMBERS VT 111(10) = 0.060 v at T=300K exp( 30) ~ 1013 PROPERTIES OF SILICON AT 300K Descrigtion Symbol Vaiuc Band gap energy EG 1.12 eV Intrinsic carrier m 1010 cm‘3 concentration Dielectn'c permittivity gSi 1.0x 1 0'12 F/cm Problem 1: BIT Amplifiers [16 pts] Consider the BIT amplifier shown below. Ignore EarEy effect for all cases. a) [2 pts] How does R1 and R2 help the ampiifier? to minimiag umfmhm b) [2 pts} What is the purpose of having RE? ‘miflimiié Hm: QHEL/E Varim‘fim in E1 W4 K2 c) [6 pt] What are the input and output resistances? 20w: : Ru d) {3 pts] What is the small signal voltage gain? 9) [3 pts]Now consider that a PNP transistor is added to the emitter of the amplifier as shown below. What wiil be the small signal voltage gain? P N p Ham sis who” AV :5 -— 9m {6/ 19 goat-ms E {g shat-{cl W 63L- PROB 2. B]? Amplifiers and Cascades [16 pts]. a) {6 pts} What is the gain of the following amplifier? Where would you use such an amplifier? Why? Ignore the early effect. RE \ Av : L {L %m+% I; '= Rm“ :i am be asgol as a; Witt/14° SW36 bttwen/m CL 62E algae div/(oi Ct Erma/ii mat. a _ .. ' 5 9‘” 'i'g flotsam; Pal—HHS} 0t CE H0332 chi’eici‘fj l’Ce 0: WWL LM‘GL‘ mam“ We; 03W: 77% poi/matim smug/L'- g/fws W344 WP“: CCU”? £5 Mid ma “Lip/ME Te; sates/r: ow» Wu m’ m 6‘va W“; b) {2 pts} How do cascodes help in amplifier design? {m p 0W4“; bilfibufi C5 amofl OL 34% Mi LN 5L . easwdgs [900% Hot; fimtpwi {mpgdmflw “Thy-Ytbg Marita/mg lheqm%: c) [4 pts} What is the maximum output impedance of the following cascade? V133 03 'X, 9mg, {5; (YGBH V732) Ra»an Rallfm‘flfit d) [4 pt] Explain why the following is not a good cascade. How will you change the design to obtain a larger small signal gain? PROB 3. Current mirrors and Frequency Response. [18 pts] a) {3 pts} Neglecting base currents find 1mm as a function of [Ref —-mu---—-¢ -- - — - — o — _ - n a na- 0 ¢ a — — _ - - -- nann-oudutunh-Q- b) [3 pts] Why is the foiiowing not a good mirror? Vcc [REF Since, VX £5 fixciokyfi (2’, the?ng mhmp WVQH {ME—fed? QREF- +1 Vx _Q1 impala Mm mid mmwi = “W? Media ummmtm @a 6&5; W 94 00% (km/WWW MWW c) {6 pts} For the foitowing, derive an expression fo [copy as a function of [Ref including the base currents. n on 1 ——“-' k} LREF * 18F+ 9' LEE? £6.13 F giiwm ‘ p‘j it~ ‘F g LE? P M + w; E (“REF m rLWW‘ 7‘\, Ram 63, C2) mad \‘jj Q ~ ‘= 2/ + W i" ‘75] d) [Zpts] Draw the high frequency modei of a CE stage. Mention physical origins for each of the capacitances in this model. 5 n ; Lie/pi won WP _ 7 C 044.96 6L4: {D H ELLE??? J pm l 6L3; S/Ldashmfi {gym-2%;- i e) [4 pts] Find out the poles of the foiiowing circuit at nodes X and Y. ‘9. " " o - 9;“ ,5“ ,p.’\ .Q- f. I r .' .. , . Iff 7‘.‘:.;,.255_Q'5l3.“re 5.’ “Mm-mil» $2.? "-6 ...
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This note was uploaded on 08/30/2011 for the course EE 105 taught by Professor King-liu during the Fall '07 term at Berkeley.

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EE 105 - Fall 2009 - Salahuddin - Midterm 2 (solution) -...

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