Solutions-March-2002-Midterm-Exam

Solutions-March-2002-Midterm-Exam - ,‘aLVT~0N§ Student...

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Unformatted text preview: ,‘aLVT~0N§ Student #: Name: CARLETON UNIVERSITY MID—TERM EXAMINATION March 2, 2002 Duration: lhour 40 minutes Electronics 97.257 Number of students: 402 Department name and course number: Course Instructor(s): R. Achar, N. Tait Lab Section: Question Max Score Marks 1 5 2 15 3 20 Total 40 AUTHORIZED MEMORANDA: NON-PROGRAMMABLE CALCULATOR Students MUST count the number of pages in this examination paper before beginning to write, and report any discrepancies immediately to a proctor. This question paper has l+6=7 pages. This examination question paper MAY NOT be taken from the examination room. This exam consists of 3 questions, which should be answered on this exam paper in the space provided. Attempt all questions. Marks allocated to each question are indicated. The total number of marks for the examination is 40. The solution must be clearly indicated. Multiple solutions or solutions that are not clearly identified, will be marked incorrect. Clearly state all assumptions made. Marks are given for your approach to the problem, so SHOW YOUR WORK! Diode: _ VD/nVT __ ) z' =z' +z' [D — [S (e l E B C . . r 2 n VT lC = fllB small Signal res1stance: d I D C [CT _ gm : — V7" I 'q— Z 23’” V at room temperature VT r0 : K14— 1C Bipolar Transistor; a Active mode operation: V35: 0.7V I, : Saturation mode operation: VCEMF 0.2V 9 g m Bipolar Transistor (continued): 6 63 © @ 97.257 Midterm Examination, March 2, 2001 2/2 Name: Student #2 Lab Section: 1) Chose the correct answer for the following multiple-choice questions. Identify the correct answer by filling in the corresponding circles with your selection a or b or c or d (5 marks). (i) The important feature of Zener diodes used in voltage regulator circuits is a) They have high zener resistance b) They have highly constant forward bias (while conducting) voltages c) They have sharp reverse breakdown voltages V d) They emit light when forward biased (ii) For a pnp transistor to be in active mode 3) Vc > VB; Vli < VB b) VC > VB; V13?) V13 C) VC < VB; VE > VB / d) VC < VB; VB < VB (iii) In general, small signal parameters of a transistor are a) mainly dependent on A. C. signal variations in active region b) mainly dependent on DC, bias currents and voltages v/ 0) usually specified by the manufacturer d) valid only for the saturation region (iv) In general, the open circuit voltage gain of a common emitter amplifier circuit a) is smaller compared to actual loaded conditions b) is larger compared to actual loaded conditions / c) is heavily dependent on the a.c. signal amplitude in the active region d) usually calculated only for the saturation region (v) The major objective of using an external resistance (RE) between Emitter and Ground, in BJT CE amplifier circuits is to a) Increase the voltage gain b) Improve Bias stability 0) Increase the output resistance d) Decrease the Input resistance 97.257 Midterm Examination, March 2, 2001 3/3 Name: Student #: Lab Section: 2) Junction Diodes (Total 15 marks) R1Z2kQ R2: l _ a) In the circuit above the diodes can be described by a piecewise linear model (battery + resistance) with VDOl=0.7V, Rm=100§2 and VD02=O.7V, RDZZOQ. Find the currents 11, 12 311C113. (5 marks) $214 0“” leg—WA“ iwfll. orifc 97.257 Midterm Examination, March 2, 2001 4/4 Name: Student #: Lab Section: For the circuit shown here, two operating points have been measured: i) V021 .3V when VS=2V ii) V0:3.8V when Vs=4.55V Using the above data, answer the following questions: b) Find VD and ID for both the above measurement cases (2 marks): i) yg=1.3v when XEZZV ' -~ "Va, L F' m _ a" . VD‘ VD: 52403 w W 2 Lay: M», ii) 29:33 when v_,=4.55v VD: 0°?EV VD ; 4%? 3‘8,- 0'75‘1/3 fpfiéz gagm/Jr 1D: 3»?hfl’ c) Using the above results, calculate the piecewise linear model (battery + resistance) parameters, VDQ and RD, for the diode (4 marks): Q3 ,- «3 - /w0 Lmrw/f lw3X/o RD: 0“} ' V96 +3‘YX/53/{nro‘75 @ arm/53123 :o'og ‘ RD: 6 VDC; 0&0 }-7G3X/0~3r{9 i2.,,:____, :c H V V P I d) Using the results of part b) for two measurement points, calculate the diode equation parameters 15 and n for this diode (you can simplify your calculations by neglecting the —l ’ term in the diode current equation) (4 marks): Vfll [h V: t_, Ver V «1‘, TC, WA .2; LA; (RDl/“ u ,/ 6192': f/s‘p‘ V130: 97.257 Midterm Examination, March 2, 2001 5/5 Name: Student #2 Lab Section: 3) Bipolar Junction Transistor. Use [3:100 and VBE=O.7V, for an active operation for small signal AC analysis (Total 20 marks). 0C7- ? we r IEzfsoJ'm/i (“+1 (7 .a I ~ ,4 , , I : L ~ Slaaim =‘e3 3“ lg 34¢” 0‘99 4% “3—4 Ar V6; 71426 ; ('O‘mAthsg/wl; (HSZBV VB: 5443‘], - 3 V : ~343l/ V112): Vera-Wiw’ I 04' _ VC—M’ , ‘ \/ :— i “34.3 Va : V6 140V r ‘ « ’FL,(51043+0-2,) : QOKC20~ (5104.3) 1; RI: um 14%;; 97.257 Midterm Examination, March 2, 2001 6/6 Name: Student #: Lab Section: ‘2 $_‘ , .2: RC3“ ill-“343 , r Big. c W: 30 50% ‘7 Re :f-éfék.L c) Find RC and R1 (2 marks): 1 Mk : ;, l/ " I :1 2 0 ’ [2L { V13 T1)» 32779 :4}- ’1? C: figfiem a K1112). CRfi/Qg ‘ V (art/2L .: 20R~ T RR « t; j 2 6 I >— R1: I’Z lsoékn, f6 OQ—5CRVI‘20 k) a Sex zole- In“ Wei 2, IOU 2 ‘5’ - 0 61411 5° 24 3 For the remaining parts of this question use B=100, IC=1mA, RC=4k§2, R1=50k§2, R2=20k§2, and RE=5kQ (instead of the values from above parts). (1) Draw the equivalent circuit for small signal AC analysis. (2 marks) 97.257 Midterm Examination, March 2, 2001 7/7 Name: Student #: Lab Section: t) Find the voltage gain Av1=vo/v,-, voltage gain AVZZV/VS, the overall voltage gain AV:V0/VS and input resistance Ki (5 marks): (rfflff#,,afl_ /%u? Aagxflubi g) If the B] T output resistance r0=100k§2, find the output resistance RO (including the El T output resistance contribution) of the amplifier circuit (2 marks): _' " ll ' , :5nS/4'6m wad/(Yum fl %% if :4kflw M M a £0 ‘ l/0._6:o——'~; ...
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Solutions-March-2002-Midterm-Exam - ,‘aLVT~0N§ Student...

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