Microelectronic Devices and Circuits - EECS 105 Second Midterm Exam, Exams of Microelectronic Circuits

Download Microelectronic Devices and Circuits - EECS 105 Second Midterm Exam and more Exams Microelectronic Circuits in PDF only on Docsity! Microelectronic Devices and Circuits- EECS 105 Second Midterm Exam Wednesday, November 15, 2000 Costas J. Spanos University of California at Berkeley College of Engineering Department of Electrical Engineering and Computer Sciences Your Name: (last) (first) Your Signature: Print and sign your name on this page before you start.1. You are allowed two 8.5"x11" handwritten sheets with formulas. No books or notes!2. Do everything on this exam, and make your methods as clear as possible.3. Problem 1 / 30 Problem 2 / 40 Problem 3 / 30 University of California at Berkeley 1 TOTAL / 100 Problem 1 of 3 Answer each question briefly and clearly. Sketch a simple drawing if it helps you make your point. (30 points) What is the physical mechanism limits the maximum fT of a BJT? (6 pts) What is "base-width modulation" and how does it affect the behavior of BJT? (6pts) You are given a 2-port, which has Rin = 1KΩ, Rout = 100KΩ, and an open circuit voltage gain Av = -10. Please draw the equivalent transconductance 2-port and calculate its Rin, Rout, and Gm. (6 pts) University of California at Berkeley 2 a) draw the equivalent small signal circuit of this amplifier (10 pts) b) Sketch the 2-port Current Amp equivalent, and write expressions for Rin, Rout, and Ai. Assume that ro>>Rs and ro>>RL. (10 pts). c) Calculate the overall (loaded) current gain, (note that Vbs = 0 V). (10pts) University of California at Berkeley 5 M1 and M2 have both the same W/L. Find the value of Rref so that this current source delivers the 1 mA of supply current that is needed (for this part of the problem assume that the load draws no DC current). (10pts). University of California at Berkeley 6 Problem 3 of 3 (30 points) For each of the following questions, make sure that you show the expressions before you plug in the specific values. A correct expression is worth 70% of the credit, even if the numerical calculation is incorrect! a) Derive the transfer function Vout/Vin expression of the following amplifier (10 pts). b) Plot amplitude and phase Bode plots when R1 = 10KΩ. C1= 0.01 µF, R2 = 1KΩ. C2 = 0.001 µF, Gm = 0.01 S. (10 pts for each plot). University of California at Berkeley 7