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XC4000E and XC4000X Series Field Programmable Gate Arrays
CLB
Double-Length Lines
PSM PSM
PSM
The double-length lines consist of a grid of metal segments,
each twice as long as
the single-length lines: they
run past
two
CLBs bef ore enter ing a s witch matr ix. Double-length
lines are grouped
in pairs with the switch matrices staggered,
¤
so that each line goes
through a switch
matr ix at
every
other row or column of CLBs (see Figure 29).
There are four vertical and four horizontal double-length
lines associated with each CLB. These lines provide faster
signal routing over
intermediate distances, while retaining
routing flexibility. Double-length lines are connected by way
of the programmable
switch matrices. Routing connectivity
is shown in Figure 28.
Quad Lines (XC4000X only)
CLB CLB
CLB CLB CLB
XC4000X devices
also include tw elve vertical and tw elve
¤
horizontal quad lines
per CLB row and column. Quad lines
are four
times as long as the single-length lines . They are
interconnected via
buffered switch matrices (shown as diamonds
in Figure
28 on page 4-31). Quad lines run
past four
CLBs before
enter ing a b uffered switch matr ix. The y are
grouped
in f ours, with the b uffered switch
matr ices staggered,
so that each line goes
¤
through a buffered
s
witch
matrix at every fourth CLB location in that row or column.
(See Figure 30.)
The buffered
switch matrixes have four pins, one on
each
edge.
All of the pins are bidirectional. Any pin can drive any
or all of the other pins.
Each buffered switch matrix contains one buffer and six
pass transistors.
It resemb les the prog rammable s witch
matrix shown in Figure 27, with the addition of a prog rammable
buffer. There can be up to two independent inputs
and up to two
independent
pendent inputs can be b
§
uffe
¨¡¡
¤
The place and route softw
a
requirements of the design
quad line signal should
be b
is typically buffered, while
a
scenario
is to alter nate
bu
allows
both vertical and hor
at alternating
buffered switc
Due to the buffered switch
fast.
They provide the f ast
heavily loaded signals for lo
Longlines
§
¨
§
.
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PSM
CLB CLB CLB
Doubles
Singles
Doubles
Figure 29: Single- and Double-Length Lines, with
Programmable Switch Matrices
(PSMs)
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X6601
CLB
CLB
CLB
Figure 30: Quad Lines
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Longlines form a grid of me
run the entire length or
wi
intended for high fan-out, t
that
are distributed
o
ver
devices,
quad lines are pre
the buffered
switch matrice
out nets
Two
horizontal longlines pe
or open-drain
drivers (TBU
ment unidirectional or bidir
ers,
or wired-AND functions
page 4-27 for more details.
Each horizontal longline dr
(XC4000E) or eight (XC40
vate these resistors, attach
line net. The software autom
ate number
of pull-ups . Th
each end of these two
horiz