Motorola DSP56156 Manual page 167

If a unity gain is expected from the D/A section, the gain of that filter has to be multiplied
by 1/1.4588 in order to compensate the attenuation of the comb filter at the given decima-
tion ratio (refer to Table 6-17).
Table 6-19 Coefficient of the Filter Shown in Figure 6-31
; Source filter file: "compda105.IIR.Filter"
_filter_type
_NSTAGES
Figure 6-32 shows the overall response of the DSP IIR filter cascaded with the D/A sec-
tion.
6 - 52
APPLICATION EXAMPLES
equ BIQUAD_FILTER_TYPE
equ 4
dc $01aa
; Biquad stage no. 1
dc $d643
dc $40b9
dc $ffa6
dc $1716
; Biquad stage no. 2
dc $dab0
dc $59b0
dc $ff66
dc $15eb
; Biquad stage no. 3
dc $c8ec
dc $2f65
dc $e878
dc $da3c
; Biquad stage no. 4
dc $c5aa
dc $7990
dc $e724
dc $d908
DSP56156 ON-CHIP SIGMA/DELTA CODEC
; number of biquadratic stages
; g = 0.02600974423/2
; -d2_1 = -0.6521580312/2
; -d1_1 = 1.011306724/2
; n2_1 = -0.005487472908/2
; n1_1 = 0.3606981345/2
; -d2_2 = -0.5829883186/2
; -d1_2 = 1.401342029/2
; n2_2 = -0.009372766805/2
; n1_2 = 0.3424793475/2
; -d2_3 = -0.8605882387/2
; -d1_3 = 0.7405380828/2
; n2_3 = -0.3676882987/2
; n1_3 = -0.5901159969/2
; -d2_4 = -0.9114780943/2
; -d1_4 = 1.899401635/2
; n2_4 = -0.3884263941/2
; n1_4 = -0.6089069362/2
MOTOROLA