lab2 - Experiment-2 Experiment-2 Single-Stage BJT...

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Experiment-2 R. B. Darling EE-332 Laboratory Handbook Page E2.1 Experiment-2 Single-Stage BJT Amplifiers Introduction The objectives of this experiment are to observe the operating characteristics of the three fundamental single-stage BJT amplifiers: common-emitter, common-base, and common-collector, and to learn how to properly bias a BJT for small-signal amplification. Biasing a BJT into the forward-active region of operation is the first required step in creating an amplifer stage. Once the BJT is properly biased, various amplifier stages can be achieved by injecting a signal into one terminal and extracting a signal from another. When the BJT is regarded as a two-port network, one of the terminals must serve as a common point between the input port and the output port. If the input is on the base and the output on the collector, the emitter must therefore be common between the input and output ports, and the configuration is referred to as a common-emitter (CE) amplifier stage. Two rules apply to single stage BJT amplifiers: the base can never be an output, and the collector can never be an input. With these rules, there are three fundamental BJT amplifier stages: (1) a common- emitter (CE) where the input is on the base and the output on the collector, (2) a common-base (CB) where the input is on the emitter and the output on the collector, and (3) a common-collector (CC), also known as an emitter-follower (EF) where the input is on the base and the output is on the emitter. This laboratory experiment will examine the characteristics of each of these three fundamental amplifer configurations.
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Experiment-2 R. B. Darling EE-332 Laboratory Handbook Page E2.2 Procedure 1 NPN common-emitter stage characteristics Comments With in input signal delivered to the base terminal and the output signal pulled from the collector terminal, the emitter terminal of the BJT is common to the input and output ports. Thus, this configuration is termed a common-emitter transistor stage. In the following circuit a potentiometer R3 will be used to adjust the value of the collector resistor. To keep the value of this resistance from accidentally being reduced all the way to zero, an additional “pot-stop” resistor R2 is added in series to establish a minimum resistance for this branch. This is always good practice for potentiometers to avoid producing unwanted short circuits which could cause serious circuit problems, in this case destroying the transistor. Whenever you design a circuit with a potentiometer in it, always consider the worst cases that will occur at each of the two endpoints of the potentiometer’s settings. A little forethrought here will save you lots of parts and frustration later! Set-Up
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lab2 - Experiment-2 Experiment-2 Single-Stage BJT...

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