The following lists the coefficients and frequency response plots of all decimation filters. These are all half-band filters, so only the center tap value and the first half are listed. The N(bit) is the bit width of the coefficients and it is used for normalized coefficients.
FIR 1a (2x)
N(bit) = 17
Center Tap: 65536
First Half: 5,0,-17,0,44,0,-96,0,187,0,-335,0,565,0,-906,0,1401,0,-2112,0,3145,0,-4723,0,7415,0,-13331,0,41526
FIR 1b (3x)
N(bit) = 19
Center Tap: 174763
2,6,0,-17,-27,0,57,79,0,-143,-187,0,307,385,0,-590,-721,0,1050,1254,0,-1757,-2063,0,2807,3256,0,-4339,-4991,0,6579,7549,0,-9975,-11517,0,15633,18486,0,-27325,-34856,0,71618,144204
Figure 1. FIR 1a and FIR 1b Frequency Response (Gen 3/DFE)
FIR 1c (5x)
N(bit) = 19
Center Tap: 104858
First Half: 2,0,-4,-10,-13,-11,0,17,35,43,32,0,-47,-91,-107,-78,0,106,198,228,162,0,-210,-386,-437,-304,0,383,693,772,531,0,-652,-1166,-1286,-875,0,1056,1872,2049,1384,0,-1648,-2905,-3163,-2127,0,2514,4421,4804,3227,0,-3819,-6731,-7340,-4956,0,5956,10615,11742,8070,0,-10195,-18821,-21778,-15872,0,24203,52516,79099,98013
Figure 2. FIR 1c (5x) Frequency Response (Gen 3/DFE)
FIR 2 (2x) Coefficients:
N(bit) = 15
Center Tap: 16384
First Half: -12,0,84,0,-337,0,1008,0,-2693,0,10142
FIR 3/4 (2x) Coefficients
Note: FIR 3 and 4 have the same coefficients.
N(bit) = 12
Center Tap: 2048
First Half: -6,0,54,0,-254,0,1230
Figure 3. FIR 2, 3 and 4 Frequency Response (Gen 3/DFE)