Chapter 12 Field-Effect Transistors. Chapter 12 Field-Effect Transistors. Understand MOSFET operation. 2 . Analyze basic FET amplifiers using the load-line technique. 3 . Analyze bias circuits. 4 . Use small-signal equivalent circuits to analyze FET amplifiers.
5. Compute the performance parameters of several
FET amplifier configurations.
6. Select a FET amplifier configuration that is
appropriate for a given application.
7. Understand the basic operation of CMOS logic
Amplifier analysis has two steps:
1. Determine the Q point.
2. Use a small-signal equivalent circuit to determine impedances and gains.
In small-signal midband analysis of FET amplifiers, the coupling capacitors, bypass capacitors, and dc voltage sources are replaced by short circuits. The FET is replaced with its small-signal equivalent circuit. Then, we write circuit equations and derive useful expressions for gains, input impedance, and output impedance.
To find the output resistance of an amplifier, we disconnect the load, replace the signal source by its internal resistance, and then find the resistance looking into the output terminals.
The source follower has voltage gain slightly less than unity, high input impedance, and low output impedance. Current gain and power gain can be larger than unity.