ECE 250 Exam 2 Fall 2007-Solution

ECE 250 Exam 2 Fall 2007-Solution - Scores DQS 2;2 s 3)05...

This preview shows pages 1–7. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Scores: DQS 2).;2 s 3)05 4013 Total / 9(9 \2 I pledge on my honor that I did not copy any of this exam, and that this work is entirely my own. Furthermore, I did not use PSpice during this exam. Page 1 of 9 Problem 1 125 Points}: VCC =15V LL. Vx 5V .2; V1 1. I C2 1”” 12 1mA £3 »VEE = -15 V Source iin is a small signal ac current source. Find the bias values of VCE and Vx. Assume that VBE = 0.7 V and [3 = 100. Do not ignore base currents. \lE :1 ovubgzaau—wﬁo 2%} (9 \lg/ \lcc '13», ‘z- \50 "QMMBQ: m) Problem 2 (25 Points): VCC =15V RC i1” (.3 —VEE = -15 V Assume B = 100. Calculate a numerical value for the gain VO/im. 56m, [1d, lit—6.... :[email protected] \j—c "' 613‘? mm) a YE, 1‘ (K‘R‘ACB) :; "\fb‘éom “‘9‘ @ Page40f9 Problem 3: (25 Points) We would like to turn on and off an LED using the circuit below: VCC = 5V :3 RC U1A RB ' W t: 02 fé 3;. 7400 Assume: 0 When the logic gate output is high, the output voltage can be anywhere in the range of 3.5 V to 5 V. 0 When the output of the logic gate is high, the most current it can source is 5 mA. 0 For the BJT, 350 2 B Z 50. o The LED forward voltage drop is 1.5 V. 0 VCC = 5 0 Assume the BJT saturation voltage is 0.2 V. o This bullet was put here by accident. We want to design the circuit for the following operation. 0 When the LED is on, 30 mA of current ﬂows through the LED. 0 When the logic gate output is high, the LED should be off. 0 When the output of the logic gate is high, we want the logic gate to supply as little current as possible and still meet the speciﬁcations. (You can’t just say R3 = 10 because that will supply more than enough current.) Choose the largest values for R3 and RC that meet the above speciﬁcations and work for any logic high output and any value of B. xx)“va TM SwV’W/l’x “u DEF, M Rowe \$0 ..... , .2 ‘10 9—9-3 quvdcb‘w} 5‘) O : (’“W‘A C9 «a ’32? m H 1C \.\ («MAB q 1C? Ckougz, ’12, 2: ° a“: I SO : O M ﬁw “(\4. L&( cu d’ Page 7 of 9 Problem 4: (25 Points) A new diode has been discovered with the properties shown below: + Id Vd ‘ i __ IOU/(1)15 f0?” Vd Z 0 Where Id — {O for Vd < 0 a) In the circuit below, bias the diode so that the diode voltage Vd is 5 V. Use p = 0.001 A/V 1‘5 . (7 points) VgC = 15 V L2 R6 R5 V0 b) Using the value for of R5 determined in part a, ﬁnd a numerical value for the small signal voltage gain VO/Vm. (18 Points) QC, C2610 \T "MSG .__e‘59 5x) + RS U325d Page 8 of 9 Page 9 of 9 ...
View Full Document

{[ snackBarMessage ]}

What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern