Question

Polytechnic University of Puerto Rico Electrical & Computer Engineering and Computer Science Department Period Fall/2017 Take-home Test Title: Electronics I Section: 22 Assignment date 12/27/2817 Day to hand in: 1/8/2018 Course code: EE-2500 Professor: Rodrigo Martínez Instructions: 1 In order to get partial grade credits in the problems, it is necessary to include 2 Please, make commentaries in each important step of the problem 3 Answers without its respective procedure are not valid 4 The technical content of the report as well as the quality of the presentation, will the procedure used to obtain the answers count on the total grade of the test 5 Send the completed test in pdf to rmartineapupr.edu. You can use a scanner with pdf capabilities to scan your handwritten exam. You should also include these pages Problem 1 For the amplifier shown in Figure 1, determine the expression for vo(t) Data R1=22 kΩ Vsa(t) = 300s in(6,000rt) mv Use LTspice to simulate the amplifier. Give the printouts of the input and the output waveforms using only 3 periods in order to observe their properties. Mark the most important points of the waveforms Compare the calculated values with the values obtained in LTspice and comment your results. sig +V Ri OPAMP LT1007 Figure1

Answer 1

Given tha t V_cc = 7 v R_1 = 22 k ohm R_2 = 2 k ohm R_3 = 20 k ohm R_4 = 109 k ohm R_L = 1.5 k ohm V_ = 300 sin () mv Given operational amplifier circuit is a inverting amplifier (with negative feedback through R_4) due to Negative feedback, virtual short is possible at the inverting and non - inverting terminals is op. amp i.e. V_a = V_b let V_b = V-c c times R_2/R_1 + R_2 = 9 times 2 k/22 k = 2k = 750 mV V_a = v_sig R_4 + V_0 R_3/R_4 + R_3 V_a = V_sig (100 k) + v_0 (20 k)/100 k + 20 k 750 mV = V_sig (100 k) + V_0 (20 k)/120 k Because (v_a = v_b) (750 mv) (120 k) = (300 sin (600 pi t) xn (100 k) + v_0 (20 k) 90 times 10\^3 = 308 n