Embedded Multipliers in Cyclone II Devices
Altera provides two methods for implementing multipliers in your
design using embedded multiplier resources: instantiation and inference.
Both methods use the following three Quartus II megafunctions:
Software
Support
■
■
■
lpm_mult
altmult_add
altmult_accum
You can instantiate the megafunctions in the Quartus II software to use
the embedded multipliers. You can use the lpm_multand
altmult_addmegafunctions to implement multipliers. Additionally,
you can use the altmult_addmegafunctions to implement multiplier-
adders where the embedded multiplier is used to implement the multiply
function and the adder function is implemented in LEs. The
altmult_accummegafunction implements multiply accumulate
functions where the embedded multiplier implements the multiplier and
the accumulator function is implemented in LEs.
f
f
See Quartus II On-Line Help for instructions on using the megafunctions
and the MegaWizard Plug-In Manager.
For information on our complete DSP Design and Intellectual Property
offerings, see www.Altera.com.
You can also infer the megafunctions by creating an HDL design and
synthesize it using Quartus II integrated synthesis or a third-party
synthesis tool that recognizes and infers the appropriate multiplier
megafunction. Using either method, the Quartus II software maps the
multiplier functionality to the embedded multipliers during compilation.
f
See the Synthesis section in Volume 1 of the Quartus II Handbook for
more information.
The Cyclone II device embedded multipliers are optimized to support
multiplier-intensive DSP applications such as FIR filters, FFT functions
and encoders. These embedded multipliers can be configured to
implement multipliers of various bit widths up to 18-bits to suit a
particular application resulting in efficient resource utilization and
improved performance and data throughput. The Quartus II software,
together with the LeonardoSpectrum and Synplify software provide a
complete and easy-to-use flow for implementing multiplier functions
using embedded multipliers.
Conclusion
Altera Corporation
February 2007
12–9
Cyclone II Device Handbook, Volume 1
ALTERA [ ALTERA CORPORATION ]
