EP3SL150F780I3N Altera, EP3SL150F780I3N Datasheet - Page 148

• Manufacturer Part Number: EP3SL150F780I3N
• Description: Stratix III
• Manufacturer: Altera

Application Examples
Figure 5–24. Radix-4 Butterfly
5–48
Stratix III Device Handbook, Volume 1
RAM
RAM
RAM
RAM
A0
A1
A2
A3
X[k,0]
X[k,1]
X[k,2]
X[k,3]
FFT Example
The Fast Fourier Transform (FFT) is a very common DSP function used to
convert samples in the time domain to and from the frequency domain.
A fundamental building block of the FFT is the FFT butterfly. FFTs are
most efficient when operating on complex samples. You can use the
Stratix III DSP block to form the core of a complex FFT butterfly very
efficiently.
In
complex multipliers. This can be implemented in Stratix III using three
half-DSP blocks assuming that the data and twiddle wordlengths are
18 bits or fewer.
Figure
5–24, a radix-4 butterfly is shown. Each butterfly requires three
G[k,1]
G[k,2]
G[k,3]
G[k,0]
ROM
0
FFT ENGINE
ROM
1
ROM
2
H[k,0]
H[k,1]
H[k,2]
H[k,3]
BFPU
BFPU
BFPU
BFPU
Altera Corporation
October 2007
RAM
RAM
RAM
RAM
A0
A1
A2
A3