Unfolding and Folding of Architectures - Digital Design of Signal Processing Systems: A Practical Approach - page 365

x n x n-1 x n-2

f s

x n

x n-3 x n-4 x n-5 x n-6

h 0
h 3
h 6

h 1
h 4
h 7

h 2
h 5
h 8

0
1
2

0
1
2

0
1
2

x x x

cntr s cntr

0
2
1

0
1
2

0
1
2

+ + +

x n-7 x n-8

2
1
0 y n

0 1 2 0 1 2 0 1 2

cntr

h 0
h 3
h 6

h 1
h 4
h 7

h 2
h 5
h 8

r 0 r 3 r 6

r 1 r 4 r 7

r 2 r 5 r 8

f clk

rst_n

(a) (b)

Figure 8.12 Folded-by-3 architecture for a 9-coefficient FIR filter. (a) Folded DF architecture. (b) Folded TDF architecture