OR3C80 datasheet(27/210 Pages) AGERE

27 / 210 page

Lucent Technologies Inc.

Data Sheet

June 1999

ORCA Series 3C and 3T FPGAs

Programmable Logic Cells (continued)

PLC Routing Resources

Generally, the

ORCA Foundry Development System is

used to automatically route interconnections. Interac-

tive routing with the

ORCA Foundry design editor

(EPIC) is also available for design optimization. To use

EPIC for interactive layout, an understanding of the

routing resources is needed and is provided in this sec-

tion.

The routing resources consist of switching circuitry and

metal interconnect segments. Generally, the metal lines

which carry the signals are designated as routing seg-

ments. The switching circuitry connects the routing

segments, providing one or more of three basic func-

tions: signal switching, amplification, and isolation. A

net running from a PFU or PIC output (source) to a

PLC or PIC input (destination) consists of one or more

routing segments, connected by switching circuitry

called configurable interconnect points (CIPs).

The following sections discuss PLC, PIC, and interquad

routing resources. This section discusses the PLC

switching circuitry, intra-PLC routing, inter-PLC routing,

and clock distribution.

Configurable Interconnect Points

The process of connecting routing segments uses

three basic types of switching circuits: two types of con-

figurable interconnect points (CIPs) and bidirectional

buffers (BIDIs). The basic element in CIPs is one or

more pass transistors, each controlled by a configura-

tion RAM bit. The two types of CIPs are the mutually

exclusive (or multiplexed) CIP and the independent CIP.

A mutually exclusive set of CIPs contains two or more

CIPs, only one of which can be on at a time. An inde-

pendent CIP has no such restrictions and can be on

independent of the state of other CIPs. Figure 18

shows an example of both types of CIPs.

Key: C = configuration data.

5-5973(C)

Figure 18. Configurable Interconnect Point

3-Statable Bidirectional Buffers

Bidirectional buffers, previously described in the SLIC

section of the programmable logic cell discussion, pro-

vide isolation as well as amplification for signals routed

a long distance. Bidirectional buffers are also used to

route signals diagonally in the PLC (described later in

the subsection entitled Intra-PLC Routing), and BIDIs

can be used to indirectly route signals through the

switching routing (xSW) segments. Any number from

zero to ten BIDIs can be used in a given PLC.

MULTIPLEXED CIP

INDEPENDENT CIP

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