Altera Stratix - Page 328

7–42 Altera Corporation
Stratix Device Handbook, Volume 2 September 2004
Infinite Impulse Response (IIR) Filters
Figure 7–24. Butterworth Filter Biquad Notes (1), (2)
Notes to Figure 7–24:
(1) Unused ports are grayed out.
(2) The z
-1
coefficient is a multiple of the other coefficients (z-2 and 1) in the
feedforward path. This is implemented using a shift operation.
w(n-1)
w(n-2)
b
1
b
2
w(n)
w(n-1)
y(n)
x
(
n
)
DSP block
w(n)
DQ
D
Q