CMOS Analog Circuit Design : Comparators (#006)

Description

This module examines comparators. Comparators are used to sense when an input signal is above or below a reference voltage. In the basic form, the comparator is nothing more than a 1-bit analog-to-digital converter. The input of the comparator functions in the analog domain while the output functions in the digital domain. The comparator is only active when the two inputs are closed to each other. For all else, the comparator output is either high or low. The types of comparators that are presented include the open-loop comparator, the latch, and combinations of the open-loop and latch comparator. The open-loop comparator is essentially an op amp without any compensation. The latch uses positive feedback to take an unknown difference and cause it to be amplified. The fastest comparators use a combination of open-loop and latch type comparators.
Lectures

1. Open-Loop Comparators
2. Improved Open-Loop Comparators and Latches
3. High speed comparators