Motorola DSP56156 Manual page 151

If a unity gain is expected from the D/A section, the gain of that filter has to be multiplied
by 1/1.7366 in order to compensate the attenuation of the comb filter at the given decima-
tion ratio (refer to Table 6-11).
Table 6-13 Coefficient of the Filter Shown in Figure 6-19
; Source filter file: "compda125.IIR.Filter"
_filter_type
_NSTAGES
Figure 6-20 shows the overall response of the DSP IIR filter cascaded with the D/A sec-
tion.
6 - 36
APPLICATION EXAMPLES
equ BIQUAD_FILTER_TYPE
equ 4
dc $00a6
; Biquad stage no. 1
dc $cd33
dc $2a8b
dc $2fc9
dc $631a
; Biquad stage no. 2
dc $e357
dc $2c13
dc $d70a
dc $ea14
; Biquad stage no. 3
dc $e6b6
dc $4431
dc $dd2e
dc $e35a
; Biquad stage no. 4
dc $c629
dc $7923
dc $19a1
dc $5060
DSP56156 ON-CHIP SIGMA/DELTA CODEC
; number of stages
; gain = 0.01012690668/2
; -d2_1 = -0.7937344327/2
; -d1_1 = 0.6647261771/2
; n2_1 = 0.7466289714/2
; n1_1 = 1.548444641/2
; -d2_2 = -0.4478366909/2
; -d1_2 = 0.6886420446/2
; n2_2 = -0.6400153519/2
; n1_2 = -0.3425524844/2
; -d2_3 = -0.395159897/2
; -d1_3 = 1.065511376/2
; n2_3 = -0.5440372612/2
; n1_3 = -0.4476206714/2
; -d2_4 = -0.9037268127/2
; -d1_4 = 1.892747933/2
; n2_4 = 0.4004225192/2
; n1_4 = 1.255851238/2
MOTOROLA