Data Sheet
June 1999
ORCA Series 2 FPGAs
binatorial mode, the LUTs can realize any four-, five-,
or six-input logic functions. In ripple mode, the high-
speed carry logic is used for arithmetic functions, the
new multiplier function, or the enhanced data path
functions. In memory mode, the LUTs can be used as a
16 x 4 read/write or read-only memory (asynchronous
mode or the new synchronous mode) or a new 16 x 2
dual-port memory.
ORCA Foundry Development System
Overview
The ORCA Foundry Development System interfaces to
front-end design entry tools and provides the tools to
produce a configured FPGA. In the design flow, the
user defines the functionality of the FPGA at two
points: at design entry and at the bit stream generation
stage.
Following design entry, the development system’s map,
place, and route tools translate the netlist into a routed
FPGA. Its bit stream generator is then used to generate
the configuration data which is loaded into the FPGA’s
internal configuration RAM. When using the bit stream
generator, the user selects options that affect the func-
tionality of the FPGA. Combined with the front-end
tools, ORCA Foundry produces configuration data that
implements the various logic and routing options dis-
cussed in this data sheet.
Programmable Logic Cells
The programmable logic cell (PLC) consists of a pro-
grammable function unit (PFU) and routing resources.
All PLCs in the array are identical. The PFU, which con-
tains four LUTs and four latches/FFs for logic imple-
mentation, is discussed in the next section.
Programmable Function Unit
The PFUs are used for logic. Each PFU has 19 exter-
nal inputs and six outputs and can operate in several
modes. The functionality of the inputs and outputs
depends on the operating mode.
Architecture
The ORCA Series FPGA is comprised of two basic
elements: PLCs and PICs. Figure 1 shows an array of
programmable logic cells (PLCs) surrounded by pro-
grammable input/output cells (PICs). The Series 2 has
PLCs arranged in an array of 20 rows and 20 columns.
PICs are located on all four sides of the FPGA between
the PLCs and the IC edge.
The PFU uses three input data buses (A[4:0], B[4:0],
WD[3:0]), four control inputs (C0, CK, CE, LSR), and a
carry input (CIN); the last is used for fast arithmetic
functions. There is a 5-bit output bus (O[4:0]) and a
carry-out (COUT).
The location of a PLC is indicated by its row and col-
umn so that a PLC in the second row and third column
is R2C3. PICs are indicated similarly, with PT (top) and
PB (bottom) designating rows and PL (left) and PR
(right) designating columns, followed by a number. The
routing resources and configuration RAM are not
shown, but the interquad routing blocks (hIQ, vIQ)
present in the Series 2 series are shown.
PROGRAMMABLE LOGIC CELL (PLC)
WD3
WD2
WD1
COUT
WD0
A4
A3
A2
A1
A0
O4
O3
O2
O1
O0
Each PIC contains the necessary I/O buffers to inter-
face to bond pads. The PICs also contain the routing
resources needed to connect signals from the bond
pads to/from PLCs. The PICs do not contain any user-
accessible logic elements, such as flip-flops.
PROGRAMMABLE
FUNCTION UNIT
(PFU)
B4
B3
B2
B1
B0
Combinatorial logic is done in look-up tables (LUTs)
located in the PFU. The PFU can be used in different
modes to meet different logic requirements. The LUT’s
configurable medium-/large-grain architecture can be
used to implement from one to four combinatorial logic
functions. The flexibility of the LUT to handle wide input
functions, as well as multiple smaller input functions,
maximizes the gate count/PFU.
C0 CK CE LSR
CIN
(ROUTING RESOURCES, CONFIGURATION RAM)
5-2750(F).r3
Figure 2. PFU Ports
The LUTs can be programmed to operate in one of
three modes: combinatorial, ripple, or memory. In com-
Lucent Technologies Inc.
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