UNIVERSITY OF CALIFORNIA AT BERKELEY College of Engineering Department of Electrical Engineering and Computer Sciences EE105 Lab Experiments Report 5 Single Stage BJT Amplifiers Common Collector and Common Base Name Lab Section 1 Lab Questions 3 1 2 4 CB Amplifier Parameters Av Rin Rout 3 1 5 Suppose the source resistance of VIN is 50 Would the CB amplifier amplify a signal from this source well Why 3 2 2 DC voltage values when biased at maximum output voltage swing VIN VOUT Output Voltage Swing 3 2 3 CC amplifier parameters Av Rin 1 2 POST LAB QUESTIONS 2 Rout 3 2 4 Another name for the CC amplifier is the emitter follower Based on the gain that you have found why do you think it has this name 3 3 3 Is the output of the common collector speaker amplifier louder quieter or about the same as when the signal was directly applied using the function generator Why Hint The output impedance of the function generator is 50 2 Post lab Questions 2 1 Common Collector Amplifier as a Voltage Buffer 1 Even though the common collector amplifier has almost unity gain why is it still a useful amplifier configuration 2 What are the advantages or disadvantages of using a larger RE in our common collector amplifier 2 POST LAB QUESTIONS 2 2 3 Common Base Amplifier as a Current Buffer 1 The CB amplifier is rarely used as a voltage or transconductance amplifier the CE amplifier is typically used instead Based on the values of the CB and CE amplifier two port parameters you found during the labs explain why this is the case 2 The CB amplifier is commonly used as a current amplifier Approximate the current gain of a CB amplifier Hint What is the relationship between the emitter and collector currents of a CB amplifier Draw the two port model of the CB current amplifier and find Ai 3 Suppose that a small signal current of 10 A peak to peak is applied directly to a load resistor of 5 k Assuming the source resistance is 100 what is the peak to peak current flowing through the load resistor 2 POST LAB QUESTIONS 4 4 Now assume the small signal current of 10 A peak to peak with source resistance of 100 is applied to the input of the CB amplifier Assume a 5 k load resistor is also attached to the output of the CB amplifier Using the two port characteristics found during lab and the approximated current gain what is the current flowing through the load resistor Based on this result why is the CB amplifier used as a current buffer
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