U. Glaeser

Communication devices need to be of small size and low power dissipation for portability and need
to be operated at very high speed. Any of these devices, as other digital products, may consist of a single
integrated circuit (IC) or more likely many ICs mounted on a printed circuit broad (PCB). Although
the new technology (small feature size) has resulted in higher speed ICs, the transfer of data from one
IC to another still creates a bottleneck of information. The I/O pads, with their increasing inductance,
cause supply surges that compromise signal integrity. As an alternative to PCB design, another design
approach known as multichip module (MCM) consists of placing more than one chip in the same
package. The connections between modules have a large capacitive load that slows down communication
among all of the modules. In the late 1990s, a new paradigm design called system-on-a-chip (SoC) has
been successfully used to integrate the components of an entire system on one chip. This is in contrast
to the traditional design where the components are implemented in separate ICs and then assembled on
a PCB.
Section 42.3 describes the new design paradigm of a SoC and its beneficial attributes are outlined.
The remainder of the paper concentrates on communication devices and the subsection on “Need for
Communication Systems” emphasizes the need for these systems. Descriptions of communication SoCs
and projections on their characteristics are given in “Communication SoCs.” Latency, an important
attribute, is the subject of “System Latency”; and “Communication MCMs” describes the integration of
these systems with analog parts in MCM.
System-on-a-Chip (SoC)
The shift toward very deep submicron technology has encouraged IC designers to increase the complexity
of their designs to the extent that an entire system is now implemented on a single chip. To increase the
design productivity and decrease time-to-market, reuse of previously designed modules is becoming
common practice in SoC design; however, the reuse approach is not limited to in-house designs. It is
extended to modules that have been designed by others as well. Such modules are referred to as embedded
cores. This design approach has encouraged the founding of several companies that specialize in providing
embedded cores to service multiple customers. It is predicted that in the near future, cores, of which
40% to 60% will be from external sources [Smith 1997], will populate 90% of a chip. Except for a very
few, individual companies do not have the wide range of expertise that can match the spectrum of design
types in demand today.
Core-based design, justified by the need to decrease time-to-market, has created a host of challenging
problems for the design and testing community. First, there are legal issues for the core provider and the
user, regarding the intellectual property (IP). Second, there are problems with integrating and verifying
a mix of proprietary and external cores that are more involved than simply integrating ICs on a PCB.
A typical SoC configuration is shown in Fig. 42.9. It consists of several cores that are also referred to
as modules, blocks, or macros. Often, these terms are used interchangeably. These cores may be DSP, RAM
FIGURE 42.9 A system-on-a-chip (SoC).
© 2002 by CRC Press LLC