TABLE OF CONTENTS In the previous two chapters, we have focused on the op amp and its design. Before considering how the op amp is used to accomplish various types of analog signal processing and analog digital conversion, we will examine the comparator. The comparator is a circuit that compares an analog signal with another analog signal or reference and outputs a binary signal based on the comparison. What is meant here by an analog signal is one that can have any of a continuum of amplitude values at a given point in time (see Section 1.1). In the strictest sense a binary signal can have only one of two given values at any point in time, but this concept of a binary signal is too ideal for real-world situations, where there is a transition region between the two binary states. It is important for the comparator to pass quickly through the transition region.
The comparator is widely used in the process of converting analog signals to digital signals. In the analog-to-digital conversion process, it is necessary to first sample the input. This sampled signal is then applied to a combination of comparators to determine the digital equivalent of the analog signal. In its simplest form, the comparator can be considered as a 1-bit analog digital converter. The application of the comparator in analog-to-digital converters will be presented in Chapter 10.
The presentation on comparators will first examine the requirements and characterization of comparators. It will be seen that comparators can be divided into...
