Motorola DSP56156 Manual page 148

If a unity gain is expected from the A/D section, the gain of that filter has to be multiplied
by 1/0.9313 in order to compensate the attenuation of the comb filter at the given decima-
tion ratio (refer to Table 6-11).
Table 6-12 Coefficient of the Filter Shown in Figure 6-17
; Source filter file: "compad125.IIR.Filter"
_filter_type
_NSTAGES
Figure 6-18 shows the overall response of the A/D section cascaded with the DSP IIR filter
described above.
MOTOROLA
APPLICATION EXAMPLES
equ BIQUAD_FILTER_TYPE
equ 4
dc $00e1
; Biquad stage no. 1
dc $ca7f
dc $2dfe
dc $2d53
dc $509d
; Biquad stage no. 2
dc $df76
dc $37c5
dc $dadc
dc $e66c
; Biquad stage no. 3
dc $e42a
dc $4b16
dc $dd3d
dc $e3c4
; Biquad stage no. 4
dc $c60b
dc $7940
dc $f477
dc $285f
DSP56156 ON-CHIP SIGMA/DELTA CODEC
; number of stages
; gain = 0.01371465707/2
; -d2_1 = -0.8360288598/2
; -d1_1 = 0.7186447751/2
; n2_1 = 0.7081856555/2
; n1_1 = 1.259552697/2
; -d2_2 = -0.5084528045/2
; -d1_2 = 0.8713790964/2
; n2_2 = -0.5803458289/2
; n1_2 = -0.3996296048/2
; -d2_3 = -0.434960982/2
; -d1_3 = 1.173228867/2
; n2_3 = -0.5431805183/2
; n1_3 = -0.4411614171/2
; -d2_4 = -0.9055949256/2
; -d1_4 = 1.894549449/2
; n2_4 = -0.1802356271/2
; n1_4 = 0.6307957449/2
6 - 33