XP2 Datasheet, PDF (22/92 Pages) Lattice Semiconductor – LatticeXP2 Family Data Sheet

Lattice Semiconductor
Architecture
LatticeXP2 Family Data Sheet
Figure 2-19. Comparison of General DSP and LatticeXP2 Approaches
Operand
A
Operand
B
Single
Multiplier
x
Operand
A
Operand
A
Operand
B
Operand
B
M loops
x x Multiplier 0
Multiplier 1
Operand
A
Operand
B
x
Multiplier k
m/k
loops
Accumulator
Function implemented in
General purpose DSP
(k adds)
+
m/k
accumulate
Output
Function implemented
in LatticeXP2
sysDSP Block Capabilities
The sysDSP block in the LatticeXP2 family supports four functional elements in three 9, 18 and 36 data path
widths. The user selects a function element for a DSP block and then selects the width and type (signed/unsigned)
of its operands. The operands in the LatticeXP2 family sysDSP Blocks can be either signed or unsigned but not
mixed within a function element. Similarly, the operand widths cannot be mixed within a block. DSP elements can
be concatenated.
The resources in each sysDSP block can be configured to support the following four elements:
• MULT (Multiply)
• MAC (Multiply, Accumulate)
• MULTADDSUB (Multiply, Addition/Subtraction)
• MULTADDSUBSUM (Multiply, Addition/Subtraction, Accumulate)
The number of elements available in each block depends on the width selected from the three available options: x9,
x18, and x36. A number of these elements are concatenated for highly parallel implementations of DSP functions.
Table 2-6 shows the capabilities of the block.
Table 2-6. Maximum Number of Elements in a Block
Width of Multiply
x9
MULT
8
MAC
2
MULTADDSUB
4
MULTADDSUBSUM
2
x18
x36
4
1
2
—
2
—
1
—
Some options are available in four elements. The input register in all the elements can be directly loaded or can be
loaded as shift register from previous operand registers. By selecting ‘dynamic operation’ the following operations
are possible:
2-19