The goals of this lab are to become familiar with gain/bandwidth, with a common-emitter (CE) amplifier, and with LTspice. To do this the pre-lab required use of LTSpice to build and analyze a virtual version of the CE amplifier circuit. This familiarized me with the basic operations of LTSpice by guiding me through building virtual circuits. It also taught me how to perform simulations of the circuits such as dc operating point and transient analysis. This included taking single measurements of specific aspects of the circuit ,such as collector and emitter current and power dissipation, and analysis of how the circuit behaved over time through measuring the input and output signals over time.
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During the lab, I breadboarded and tested a CE amplifier circuit. By doing this I became more familiar with the concept of gain and the common emitter amplifier circuit. One thing I learned is that it is best to observe the input and the output signals when measuring the gain of an amplifier because generators usually have some nonlinearity that causes their output voltage to vary with frequency. Another thing is that gain stays relatively steady over a large range of resistance values at the load for a given frequency. The same holds true for a large range of frequencies with a given load resistance.
The lab also served as a refresher on the common emitter amplifier and increased my knowledge of it. It reminded me how to design the dc biasing portion of the circuit and how to calculate the Q-point of a pre-designed circuit. It also, showed me how to actually use the amplifier whereas previously, I only knew how to build one, but not what to use it for. In addition, I found out that R1 and R2 are in parallel when looking at the circuit from an AC standpoint because Vcc is an AC ground. I also learned that transconductance is related to gain by the negative parallel combination of the coupling and load resistor.