Altera FFT MegaCore Function - Manual (Page 38)

Parameter Value Description
I/O Data Flow Streaming
Variable Streaming
Buffered Burst
Burst
If you select Variable Streaming and Floating
Point, the precision is automatically set to 32, and
the reverse I/O order options are Digit Reverse
Order.
I/O Order Bit Reverse Order,
Digit Reverse Order,
Natural Order, N/2
to N/2
The input and output order for data entering and
leaving the FFT (variable streaming FFT only).
The Digit Reverse Order option replaces the Bit
Reverse Order in variable streaming floating
point variations.
Data Representation Fixed point or single
floating point, or
block floating point
The internal data representation type (variable
streaming FFT only), either fixed point with
natural bit-growth or single precision floating
point. Floating-point bidirectional IP cores expect
input in natural order for forward transforms and
digit reverse order for reverse transforms. The
output order is digit reverse order for forward
transforms and natural order for reverse
transforms.
Data Width 8, 10, 12, 14, 16, 18,
20, 24, 28, 32
The data precision. The values 28 and 32 are
available for variable streaming only.
Twiddle Width 8, 10, 12, 14, 16, 18,
20, 24, 28, 32
The twiddle precision. The values 28 and 32 are
available for variable streaming only. Twiddle
factor precision must be less than or equal to data
precision.
The FFT IP core's advanced parameters.
Table 3-5: Advanced Parameters
Parameter Value Description
FFT Engine Architec‐
ture
Quad Output, Single
Output
Choose between one, two, and four quad-output
FFT engines working in parallel. Alternatively, if
you have selected a single-output FFT engine
architecture, you may choose to implement one
or two engines in parallel. Multiple parallel
engines reduce transform time at the expense of
device resources, which allows you to select the
desired area and throughput trade-off point.
Not available for variable streaming or streaming
FFTs.
Number of Parallel
FFT Engines
1, 2, 4
UG-FFT
2014.12.15
FFT IP Core Parameters 3-15
FFT IP Core Functional Description Altera Corporation
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