Page 292 - DSP Integrated Circuits

DSP SYSTEM DESIGN

7.1 INTRODUCTION

In this chapter we will discuss some of the most important steps in the system
design phase. As illustrated in Figure 7.1, the system design phase follows the
specification phase and involves a number of design steps that ultimately lead to a
logical description of the architectural components. After the system design phase
follows the integrated circuit design phase, which involves circuit design, electri-
cal validation, floor planning, layout, etc. In this chapter we assume that the spec-
ification and algorithm design phases have been completed. The first step in the
system design phase involves hierarchically partitioning the DSP system into a
set of cooperating processes. These processes are then scheduled in such a way
that they can be mapped onto suitable software-hardware structures. The design
of the hardware structures will be discussed in subsequent chapters.
The purpose of the scheduling is to dis-
tribute the processes in time so that the
amount of hardware required is minimized.
The underlying assumption is that minimiz-
ing the amount of hardware will also mini-
mize the power consumption. Because of the
complexity involved, in practice often only the
number of PEs is minimized. We will present
a design approach that also makes it possible
to minimize the memory and communication
requirements.
In Chapter 9, we will present methods of
synthesizing optimal architectures based on
schedules derived in this chapter. Good
scheduling techniques are essential for the
synthesis of efficient architectures that match
the algorithm well. Most digital signal pro-
cessing algorithms allow a static scheduling
of operations which avoids the significant
work load that dynamic scheduling generally Figure 7.1 The main phases in the
represents in real-time systems. design of a DSP system