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Old_Test_2_Solution

# Old_Test_2_Solution - ECE3040D/RPK/RPY Name 30/c ”£19 to...

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Unformatted text preview: ECE3040D/RPK/RPY Name: 30 /c ”£19 to Spring 2004 Test #2 E-mail: Please .\'IZ!()W all work in the Space provided Use back if necessary. Calculate results {0 2 Signiﬁcant ﬁgures: Inc/ride appropriate 2min; m UH answers: ( iris/c or underline/final answer. Tulcdpoirzm 100. l. (30p0mrs rural) Consider the Following silicon NPN transistor structure. Assume: kTq = 25.9 m 1-" Emitrer ‘ j . . . A (“oi/cam ‘ NDF 10" cm NBC 10mm?" 0 .3 m: 10‘ cm 1)pa=3.6cm .5 l .l " h. ' 3". Dpf=llcm3s a) (10 pts) Sketch the minority carrier concentration in each region for active bias. Calculate values at depletion region edges according to the expressions below. A proximate small values} as zero \‘i here a appropriate. 7 {[1] 5 ﬁx; 1 0 5’. 0 Leg 1 . l L ' 5 :M6 'Zl‘Z/O Pun! ( «#an szdtlb " / CUE/4r ‘0‘ cI/Aﬂ‘?‘ 3y»! ”:95 ( 0) w; t ‘InE (I W W— xpC ( follecror Bare 1' Emitter b) (10 pts) What is the dominate mode ofcuirent flow (drift or diffusion) in each region ofthe BJT'? f7i'vaﬁwsr‘om / ilppt"§51’f"‘\ Collector c) (10 pts) Sketch the Ebers—Mole model to the right that is simpliﬁed for active mode operation. nl ix) £1. (.20 points rum}. wipiiiiits cue/i). Multiple choice. Circle only ONE answer. A back—to—baek (iip—pri) combination ofdiodcs does not create an iipn bipolar transistor, unless: i”. The n—regions are lower doped than the Ari-regions it Both p—regions are both depleted Which of the Following does not affect [3? i. Emitter donor concentration @ Collector donor concentration iii. Base acceptor concentration (9 The total p—region (base) width is much smaller than a diffusion length i v. A quasi—neutral region exists in both p—rcgions. What mechanism causes the Early effect (a weak dependence of collector current on collector—to— cmittcr voltage) in BJTS'? i. Variation in base width caused by variation in base—emitter depiction region ii. lligh injection ofelectrons into the collector region iii. Variation in base recombination rate due to trapped charges -.\ iv. Variation in base width caused by variation in base—collector depletion region The saturated modc ofan NPN BJT occurs under what conditions? J'. VB}; S 0 , [/f ‘11: 73' I/IEIH'. iii. V35- :i- 0. Viv; < Vii; It. VB}; 3 0 3 VCE > VBE @1317 > 01 VFE < VHE Ifthe base width \ rere increased to 2W. assuming that W-Jr-L [4), what happens to the current gain [3? i. Doubles @lalves ii. Quadruples iv. Does not change 3. (SOpUims- total) . All parts Ofthis problem refer to the Bl'l' circuit shown below. lmpedances of all capacitors may be assumed to be zero at the frequency of operation, unless otherwise stated. Operating Conditions: Transistor Parameters: 'l'emperature: T- 25 T B L: 300 H. q , 0.0259 V 1/1: —* 00 V311: 0.7 V R1; 100 M) a. (10,013) Calcrilate the values of resistors R}.- and RL- to achieve a DC Q—point 01‘ [m l0 mA and l/CEQ=4V. . l/ W at 1V , , ‘15 .. will” ”a g £1.15 .. a; -_ LEM» ..i.:. 4‘ .Lr. ' RE “(2.:- ﬁ E It,“ 30,”! ’,——: h. ([U'pm) Sketch the small—signal equivalent circuit model for the WT and external circuit. Label small—signal parameters and calculate their values. £6 G (ﬂm 4/ C ....-—--~:. 3 :8 g 1"" I471; {EM 2::- c (H)pf.\') Calculate the voltage gain 111‘. um” vm ot‘tlie smail—signal circuit. u '//:. —; 3?“ LI.“ I?C ﬂ!» Zsé . _ 7/ ‘ "' = if“! uwmxi ” Bum 5%?» ﬂy : MM -Z70—0.0%’7 : ST/ d. (ijrx) Caiculate the input and output resistances, Rm and RM El : Z: '7 7/7,: /1“ 1 Ua- (”11?ng?” M If [/r .5 I Er; i ‘7'" J _ ‘- 3 ma, tiff: ‘ : " (Mi ”tr-”W’w *éiéﬁ ﬂow 3 /?c “ 270“ \$17—1— c. (5 p15) What value of'capacitor, (I; is needed to achieve an input high—pass cut—offfrequency of 5 MHZ? —- — . Q: L 2/"! an.) ”In L f ”‘4 lb Eff : I _ ‘1 Mb” ﬂ! 7/“. 7/11 [Zita E, ﬂzfgwcﬁ / f/&V(/Zi1+ﬂI-)(j “VJ-n W) M I / L: E“ ”V" (12,.“ mm; =3 l gm (of: 7—) (1 1 (ﬁpfab,gn (AW; 77 f'. (5 pts) Suppose cx= 3 pi—'. What is the upper cut—off frequency ot‘operation? {2: W” ' Ff: w 9 Eng/mm ”i" a. if _ ,1»? /[‘£V,' (E - A ‘ ': I ? £1” 8;" ”fr/m?" "“ '9' A. 27/6407 - l i W] , zafé/{g é) ﬁfﬁ‘ “Vi?” n4 ZWHWZ/Jﬂ ”If" L L t L .1 ...
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