GC2011A Datasheet, PDF (9/50 Pages) Texas Instruments – 3.3V DIGITAL FILTER CHIP

GC2011A 3.3V DIGITAL FILTER CHIP
SLWS129A
2.1 TRANSVERSAL FILTERS
The chip implements finite impulse response (FIR) transversal filters defined by Equation (1):
N–1
∑ ^{y(n) = h(k)x(n – k)}
Eq. (1)
k=0
where x(n) is the input sample at time n, y(n) is the output sample at time n, N is the number of taps in the filter and h(k)
are the filter coefficients. Many common filters are symmetric, meaning the tap coefficients are symmetric about the
center tap. For example, the 16 coefficients (1, 2, 3, 4, 5, 6, 7, 8, 8, 7, 6, 5, 4, 3, 2, 1) have even-length symmetry. The
15 coefficients (1, 2, 3, 4, 5, 6, 7, 8, 7, 6, 5, 4, 3, 2, 1) have odd-length symmetry. Figure 2 shows the basic transversal
filter structure for an 8 tap non-symmetric filter, a 16 tap even symmetry filter and a 15 tap odd symmetry filter (actual
GC2011A filter sizes are up to 256 taps).
x(n)
h₀
h₁
h₂
h₃
h₄
h₅
h₆
h₇
y(n)
(a) 8 TAP NON-SYMMETRIC FILTER
x(n)
h₀
h₁
h₂
h₃
h₄
h₅
h₆
h₇
y(n)
(b) 16 TAP EVEN SYMMETRY FILTER
x(n)
h₀
h₁
h₂
h₃
h₄
h₅
h₆
h₇
y(n)
(c) 15 TAP ODD SYMMETRY FILTER
Figure 2. Basic Transversal Filters
The GC2011A chip implements the transversal filter structures shown in Figure 2 with the addition of pipeline
delays to increase the maximum clock rate of the chip. The pipeline delays add latency to the chip but do not effect its
operation.
Texas Instruments Incorporated
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