TLC32040M Datasheet, PDF (18/30 Pages) Texas Instruments – ANALOG INTERFACE CIRCUIT

TLC32040M
ANALOG INTERFACE CIRCUIT
Table 3. (sin x)/x Roll-Off
fs (Hz)
7200
8000
9600
14400
19200
20 log ^{sin π f/fs}
π f/fs
(f = 3000 Hz)
(dB)
– 2.64
– 2.11
–1.44
– 0.63
– 0.35
Note that the actual AIC (sin x)/x roll-off will be slightly less than the above figures because the AIC has less
than a 100% duty cycle hold interval.
correction filter
To compensate for the (sin x)/x roll-off of the AIC, a first-order correction filter shown below, is recommended.
u(i _{+ 1)}
+
X
Σ
+
(1– p1)P2
X
Z–1
y(i _{+ 1)}
p1
The difference equation for this correction filter is:
) + * ) ) Yi 1 p2(1 p1) (ui 1) p1 Yi
where the constant p1 determines the pole locations.
The resulting squared magnitude transfer function is:
H (f)² =
p2² (1 – p1)²
1 – 2p1 cos(2 π f/f_s) + p1²
4–18
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