Top-Down Digital VLSI Design

Chapter 8

Acquisition of Asynchronous Data

Abstract

Any digital circuit that interacts with the external world must assimilate asynchronous inputs because outside events appear at random points in time with respect to the circuit’s internal clock and operation. This gives rise to two problems, namely inconsistent data and metastable synchronizer behavior. After studying how data can become corrupted during synchronization, the text proposes various options for making sure only consistent data sets get admitted into a circuit. These techniques that can be used for safely exchanging data between distinct clock domains include unit-distance coding, suppression of jumbled data patterns, handshaking (full and partial), and FIFO synchronizers. ...