igital Systems 101 We'll begin by describing a typical synchronous circuit. Many variations are pos- ible but a simple example will be adequate to illustrate the sources of error Figure 1 shows the circuit and timing for one clocked element of the example One issue that deserves mention is this: Why use synchronous logic at all? Wouldn't asynchronous logic be faster? The answers to these questions could take a book, but here are some reasons to use synchronous designs Synchronous designs eliminate the problems associated with speed varia- tions through different paths of logic. By sampling signals at well-defined time intervals, fast paths and slow paths can be handled in a simple manner Synchronous designs work well under variations of temperature, voltage and process. This stability is key for high-volume manufacturing Many designs must be portable-that is, they must be easy to migrate to a new and improved technology(say, moving from 6 micron to. 35 micron) The deterministic behavior of synchronous designs makes them much more straightforward to move to a new technology Interfacing between two blocks of logic is simplified by defining standardized synchronous behavior. Asynchronous interfaces demand elaborate hand shaking or token passing to ensure integrity of information; synchronous designs with known timing characteristics can guarantee correct reception of Heck, I Know What a Flip Synchronous circuits are made with a mixture of combinatorial logic and Flop Is! clocked elements, such as fiip flops or registers. The clocked elements share a common clock, and all transition from one state to another on the rising edge of The Ten Commandments of Excellent DesignDigital Systems 101 2 The Ten Commandments of Excellent Design Digital Systems 101 We’ll begin by describing a typical synchronous circuit. Many variations are pos￾sible, but a simple example will be adequate to illustrate the sources of error. Figure 1 shows the circuit and timing for one clocked element of the example. One issue that deserves mention is this: Why use synchronous logic at all? Wouldn’t asynchronous logic be faster? The answers to these questions could take a book, but here are some reasons to use synchronous designs: • Synchronous designs eliminate the problems associated with speed varia￾tions through different paths of logic. By sampling signals at well-defined time intervals, fast paths and slow paths can be handled in a simple manner. • Synchronous designs work well under variations of temperature, voltage and process. This stability is key for high-volume manufacturing. • Many designs must be portable—that is, they must be easy to migrate to a new and improved technology (say, moving from .6 micron to .35 micron). The deterministic behavior of synchronous designs makes them much more straightforward to move to a new technology. • Interfacing between two blocks of logic is simplified by defining standardized synchronous behavior. Asynchronous interfaces demand elaborate hand￾shaking or token passing to ensure integrity of information; synchronous designs with known timing characteristics can guarantee correct reception of data. Heck, I Know What a Flip￾Flop Is! Synchronous circuits are made with a mixture of combinatorial logic and clocked elements, such as flip flops or registers. The clocked elements share a common clock, and all transition from one state to another on the rising edge of