Which Array Technology?
The broad categories of technologies are CMOS, BiPOLAR,
BiCMOS, and GaAs. Figure 1-4 provides a family tree of the most common
technologies, at least at this moment. Array technology is a subject
in itself and the reader is referred elsewhere for detailed discussions
on any specific process.
Figure 1-4a The Dominant Technologies
Bipolar as used in conjunction with arrays in this text
refers to ECL-internal with TTL, ECL 10K, ECL 100K I/O modes, or mixed
ECL/TTL interface capability. Not all arrays offer the ability to mix
TTL and ECL or to mix ECL 10K and ECL 100K on one chip. Some arrays
may limit the types of macros that can be placed on the I/O cells. Design
limits imposed by these restrictions are generally based on the array
The AMCC BiCMOS has the same interface capability as
the bipolar arrays while providing a CMOS internal core. BiCMOS interfaces
include CMOS, TTL, ECL 10K and ECL 100K and combinations of all. Not
all BiCMOS arrays offer the ability to mix TTL and ECL or ECL 10K and
ECL 100K on one chip.
Figure 1-4b Relations among Silicon Technologies
Ref: Design of VLSI Gate Array ICs by Ernest E. Hollis
Technology differences for VLSI are primarily speed and
power. CMOS is lower speed, lower power. Bipolar at 600MHz or 1.2GHz
and up is faster with a high power dissipation (5-7, up to 16 watts
for the fastest arrays is not unusual). BiCMOS is intended to be a combination
of these two, providing a reasonable speed (about 130MHz and up) at
greatly reduced power dissipation.
The actual maximum frequency of operation and the power
dissipation will vary from series to series even within the technologies.
Data sheets for the array series of interest should be reviewed and
compared as a first method of estimation for applicability.
Obtain Data Sheets from several vendors
Note: One array series may be lower power at one frequency
and higher power at another. Comparisons must be made using equivalent
conditions. When the conditions are not specified, ask! All vendors
maintain Field-Application Engineers that can explain how measurements
were taken or what assumptions were used.
Figure 1-4c Relations among Technologies