ACEX1 datasheet(26/86 Pages) ETC

26 / 86 page

Altera Corporation

ACEX 1K Programmable Logic Device Family Data Sheet

FastTrack Interconnect Routing Structure

In the ACEX 1K architecture, connections between LEs, EABs, and device

I/O pins are provided by the FastTrack Interconnect routing structure,

which is a series of continuous horizontal and vertical routing channels

that traverse the device. This global routing structure provides

predictable performance, even in complex designs. In contrast, the

segmented routing in FPGAs requires switch matrices to connect a

variable number of routing paths, increasing the delays between logic

resources and reducing performance.

The FastTrack Interconnect routing structure consists of row and column

interconnect channels that span the entire device. Each row of LABs is

served by a dedicated row interconnect. The row interconnect can drive

I/O pins and feed other LABs in the row. The column interconnect routes

signals between rows and can drive I/O pins.

Row channels drive into the LAB or EAB local interconnect. The row

signal is buffered at every LAB or EAB to reduce the effect of fan-out on

delay. A row channel can be driven by an LE or by one of three column

channels. These four signals feed dual 4-to-1 multiplexers that connect to

two specific row channels. These multiplexers, which are connected to

each LE, allow column channels to drive row channels even when all eight

LEs in a LAB drive the row interconnect.

Each column of LABs or EABs is served by a dedicated column

interconnect. The column interconnect that serves the EABs has twice as

many channels as other column interconnects. The column interconnect

can then drive I/O pins or another row’s interconnect to route the signals

to other LABs or EABs in the device. A signal from the column

interconnect, which can be either the output of a LE or an input from an

I/O pin, must be routed to the row interconnect before it can enter a LAB

or EAB. Each row channel that is driven by an IOE or EAB can drive one

specific column channel.

Access to row and column channels can be switched between LEs in

adjacent pairs of LABs. For example, a LE in one LAB can drive the row

and column channels normally driven by a particular LE in the adjacent

LAB in the same row, and vice versa. This flexibility enables routing

resources to be used more efficiently. Figure 13 shows the ACEX 1K LAB.

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