OR3T125-5BA352 AGERE [Agere Systems], OR3T125-5BA352 Datasheet - Page 18

• Manufacturer Part Number: OR3T125-5BA352
• Description: 3C and 3T Field-Programmable Gate Arrays
• Manufacturer: AGERE [Agere Systems]

ORCA Series 3C and 3T FPGAs
Programmable Logic Cells
In the third submode, multiplier submode, a single
PFU can affect an 8 x 1 bit (4 x 1 for half-ripple mode)
multiply and sum with a partial product (see Figure 8).
The multiplier bit is input at ASWE, and the multiplicand
bits are input at K
cant bit (MSB). K
other input to be summed) from a previous stage. If
ASWE is logical 1, the multiplicand is added to the par-
tial product. If ASWE is logical 0, 0 is added to the par-
tial product, which is the same as passing the partial
product. CIN/FCIN can bring the carry-in from the less
significant PFUs if the multiplicand is wider than 8 bits,
and COUT/FCOUT holds any carry-out from the multi-
plication, which may then be used as part of the prod-
uct or routed to another PFU in multiplier mode for
multiplicand width expansion.
Ripple mode’s fourth submode features equality
comparators. The functions that are explicitly available
are A
input on K
value of 1 on the carry-out signals valid argument. For
example, a carry-out equal to 1 in AB submode indi-
cates that the value on K
the value on K
B, and A > B are available using the same functions but
with a 0 output expected. For example, A
output indicates A < B. Table 5 shows each function
and the output expected.
If larger than 8 bits, the carry-out signal can be cas-
caded using fast-carry logic to the carry-in of any adja-
cent PFU. The use of this submode could be shown
using Figure 6, except that the CIN/FCIN input for the
least significant PFU is controlled via configuration.
Table 5. Ripple Mode Equality Comparator
18
18
Function
Equality
A
A
A
A < B
A > B
A = B
>
>
<
B, A
Functions and Outputs
B
B
B
Z
[0], and the value for B is input on K
Z
B, and A
[1]. Conversely, the functions A < B, A +
ORCA Foundry
Z
Z
[0] contains the partial product (or
[1], where K
Submode
A
A
A
A
A
A
>
>
<
<
<
Z
[0] is greater than or equal to
B
B
B
B
B
B
B, where the value for A is
7
[1] is the most signifi-
Carry-Out Is:
(continued)
True, if
>
1
1
1
0
0
0
B with a 0
Z
[1]. A
Key: C = configuration data.
ASWE
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
7
7
6
6
5
5
4
4
3
3
2
2
1
1
0
0
[1]
[0]
[1]
[0]
[1]
[0]
[1]
[0]
[1]
[0]
[1]
[0]
[1]
[0]
[1]
[0]
0
0
0
0
0
0
0
0
Figure 8. Multiplier Submode
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
+
+
+
+
+
+
+
+
K
K
K
K
K
K
K
K
7
6
5
4
3
2
1
0
C
C
Lucent Technologies Inc.
D Q
D Q
D Q
D Q
D Q
D Q
D Q
D Q
D Q
Data Sheet
June 1999
REGCOUT
COUT
F7
Q7
F6
Q6
F5
Q5
F4
Q4
F3
Q3
F2
Q2
F1
Q1
F0
Q0
5-5757(F)