UNIVERSITY OF CALIFORNIA AT BERKELEY EECS Department EECS 40 Fall 2007 Prof Chang Hasnain Homework 8 Due at 5 pm in 240 Cory on Thursday 11 15 07 Total Points 100 Put 1 your name and 2 discussion section number on your homework You need to put down all the derivation steps to obtain full credits of the problems Numerical answers alone will at best receive low percentage partial credits No late submission will be accepted except those with prior approval from Prof Chang Hasnain Problems of this HW are from Hambley 4th Edition Large Signal Modeling of Diodes 1 Load Line Analysis P10 24 10 points 2 DC Models Diode 12 points For the circuit on the left calculate the currents and voltages of each diode a assuming ideal diodes 6 pts b assuming the constant voltage drop model 0 6 V 6pts 3 Rectifier Circuits You have a device which requires DC voltage However you only have an AC voltage source You try to design a rectifier circuit In this question you may assume the diode to be ideal 27 pts a Your first approach is the circuit on the left sketch the voltage at the diode and at the resistor as a function of time There are two problems associated with this circuit What are these 4 pts b To improve on these problems you come up with the following circuit Sketch the voltage drop at the resistor qualitatively you do not need the actual values to do that 5pts Page 1 of 2 UNIVERSITY OF CALIFORNIA AT BERKELEY EECS Department c Still considering the circuit on the right assume now R 1k C 100uF and f 60Hz Calculate the approximate lowest value of the voltage drop at the resistor as a function of V1 and briefly comment on why your approximation holds 6pts d Assume now you want to assure that the voltage drop across the resistor is never lower than 0 9 what value for C do you need to choose if R and f are fixed 6pts e You now use a diode bridge full wave rectifier Draw the configuration with the smoothing capacitor and the load resistor at the output 3 pts f Repeat problem d with the configuration found in e 3 pts 4 Clipper Circuits 14 pts You have a sinusoidal input voltage adhering to 5V sin wt You have a sinusoidal input voltage adhering to 5V sin t a Design a clipper circuit using diodes assume the constant voltage drop model with 0 6V and Zener diodes ideal that clips voltages above 4V and also clips the signal during half of the time during which the input is negative 8 pts b Explain the functionality of the designed circuit Discuss voltage drops and currents of the diodes in the different phases of operation 6 pts 5 Clamp Circuits P10 76 12 pts Small Signal Modeling of Diodes 6 P10 78 6 pts 7 P10 79 6 pts 8 P10 80 6 pts 9 P10 83 7 pts Page 2 of 2
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