Question

1. Think about what you’ve learned about BJTs, both from lecture and from lab. What aspects of the transfer functions of the CE amplifier and the emitter follower can you sketch on your own (i.e. without having the PSpice simulation or Labview measurement)? What value does PSpice add to your ability to analyze these circuits?

Answer 1

Answer:

Check all the explanations below. Also check all the attached files for additional information

Explanation:

A Bipolar Junction Transistor is a semiconductor device consisting of two P-N Junctions connecting three terminals called the Base, Emitter and Collector terminals. The current and the gain of theses transistors is determined by the arrangement of these terminals. The BJT uses both electrons and holes as the charge carriers. The BJT can be of two types, the PNP and the NPN transistors.

The common emitter amplifier is a three basic single-stage bipolar junction transistor and is used as a voltage amplifier. In this configuration, the emitter terminal is common to both the collector and the base, the input to the amplifier is taken from the base while the output is taken from the collector.

The common emitter amplifier circuit is attached as a file to this solution.

The current gain of a common emitter amplifier is $\beta = \frac{\triangle I_{c} }{\triangle I_{B} }$

where $I_{c} and I_{B}$ are the collector and emitter currents respectively

The voltage gain of the amplifier is given by $A_{v} = \beta \frac{R_{c} }{R_{B} }$

$R_{c} and R_{B}$ are the collector and base resistance respectively

In an emitter follower configuration, emitter follows the voltage on the base. It is also called the common collector configuration. The collector is common to the emitter and base terminals.

The common collector configuration is shown in the second file attached

The output voltage on a common-collector amplifier will be in phase with the input voltage, making the common-collector a non-inverting amplifier circuit.

The current gain = $\beta + 1$

Voltage gain = 1 ( Approximately)

Pspice helps in the simulation and analysis of electronic and electrical circuits without going through the rigors of using a pen and paper. It also allows us to test with real data and make proper choice of values.