Differential Amplifiers: Op-Amps and Comparators

This lecture discusses the design and analysis of differential amplifiers, focusing on operational amplifiers (op-amps) and comparators. The instructor begins by correcting an exercise related to a schematic produced by Motorola, identifying various components such as PMOS and NMOS transistors. The lecture explains the configuration of a differential amplifier using PMOS inputs and a current source, detailing how the circuit operates with active loads. The instructor highlights the inversion of signals through the stages of the amplifier, illustrating the relationship between the input and output signals. The second part of the lecture introduces another schematic, prompting students to interpret the design, which includes multiple stages of amplification and inverters. The instructor emphasizes the gain characteristics of the circuit, explaining how the configuration functions as a comparator, capable of amplifying the difference between input signals significantly. The lecture concludes with a summary of the operational principles of the discussed circuits, reinforcing the concepts of differential amplification and signal comparison.