EE 321L Analog Electronics Laboratory Fall 2011Lab 8BJT Single-Stage AmplifiersIn this lab you will investigate single-stage a mplifier linearity and measure amplifier inputand output resistances.Pre-Lab1. Pick resistor values for steps 1, 3, and 4.2. Estimate the input and output resistance in step 7.3. Estimate the output resistance Routfor both small a nd large values of RSin step 9.Understand what constitutes large and small values for RS.Linearity and gainIn this section you will look at how ga in can be traded for linearity in the common-emitteramplifier. You will work with the following circuit with VCC= 15 V and VEE= 0 V:R12RERCVCCVEER1. Make RE= 0 and pick R1and R2to get IC= 1 mA, then pick RCto get VC= 7 V.Make sure you pick R1and R2so that the current through the voltag e divider is muchlarger than the current into the base.2. Apply a AC input through a capacitor directly to the ba se (make the frequency highenough to not attenuate the signal). Make the amplitude large enough to saturate atthe to p and the bottom. Compare the input and output for linearity.3. Next insert a resistor between t he source and the capacitor large enough t o makeGvo= 2, and again compare the input a nd output for linearity.4. Remove the resistor and instead adjust R1and R2and REto make Gvo= Avo= 2.Att ach the source to the capacitor and again compare the input and output for linearity.1EE 321L Analog Electronics Laboratory Fall 20115. Comment on the relationship between gain and linearity.Input resistance of the Common-Emitter AmplifierHere you will measure the input resistance of the common-emitter amplifier. O ne way to dothat is to measure the ga in with and without a resistor of similar size to the expected inputresistance.6. Build the common-emitter amplifier with dual base bias resistor R1and R2of totalresistance 10 kΩ and IC= 1 mA, VC= 7 V, VCC= 15 V, and VEE= 0 V, and coupleinput and output through capacitors. Be sure to use a sufficiently high frequency signal.7. Estimate the input resistance and measure it by measuring the gain vo/vswith andwithout the estimated resistor in place. Compare.Output Resistance of the Emitter Follower AmplifierHere you will measure the output resistance of the common emitter amplifier and its depen-dence o n the source resistance. Remember that the emitter follower is non-unilateral.8. Build t he emitter follower with RE= 5 kΩ a nd IC= 1 mA, and R1+ R2= 10 kΩ,VCC= 15 V, and VEE= 0 V.9. Estimate the output resistance for large a nd small value of RS.10. Measure the output resistance with a larg e value of RSand and small value of RSandcompare with the
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