EP3C16F256I7N Altera, EP3C16F256I7N Datasheet - Page 49

• Manufacturer Part Number: EP3C16F256I7N
• Description: Cyclone III
• Manufacturer: Altera

Chapter 3: Memory Blocks in the Cyclone III Device Family
Memory Modes
Figure 3–12. Cyclone III Device Family True Dual-Port Timing Waveforms
Shift Register Mode
© December 2009
q_a (asynch)
q_b (asynch)
address_a
address_b
data_a
rden_a
wren_a
wren_b
rden_b
clk_a
clk_b
Altera Corporation
din-1
an-1
doutn-1
Figure 3–12
and read operation at port B. Registering the outputs of the RAM simply delays the q
outputs by one clock cycle.
Cyclone III device family M9K memory blocks can implement shift registers for
digital signal processing (DSP) applications, such as finite impulse response (FIR)
filters, pseudo-random number generators, multi-channel filtering, and
auto-correlation and cross-correlation functions. These and other DSP applications
require local data storage, traditionally implemented with standard flipflops that
quickly exhaust many logic cells for large shift registers. A more efficient alternative is
to use embedded memory as a shift register block, which saves logic cell and routing
resources.
The size of a (w × m × n) shift register is determined by the input data width (w), the
length of the taps (m), and the number of taps (n), and must be less than or equal to
the maximum number of memory bits, which is 9,216 bits. In addition, the size of
(w × n) must be less than or equal to the maximum width of the block, which is 36 bits.
If you need a larger shift register, you can cascade the M9K memory blocks.
bn
din-1
din
an
shows true dual-port timing waveforms for the write operation at port A
doutn
din
b0
a0
dout0
a1
dout0
dout1
b1
a2
dout2
a3
dout3
dout1
b2
din4
a4
Cyclone III Device Handbook, Volume 1
din4
din5
a5
dout2
din5
b3
din6
a6
3–13