TLC32046MFKB datasheet(29/56 Pages) TI

29 / 56 page

Error = 20 log

sin

π f/fs

2–15

Table 2–5. (sin x)/x Roll-Off Error

fs (Hz)

f = 3000 Hz

(dB)

7200

– 2.64

8000

– 2.11

9600

– 1.44

14400

– 0.63

16000

– 0.50

19200

– 0.35

25000

– 0.21

The actual AIC (sin x)/x roll-off is slightly less than the figures in Table 2–5 because the AIC has less than

100% duty cycle hold interval.

2.27 Correction Filter

To externally compensate for the (sin x)/x roll-off of the AIC, a first-order correction filter can be implemented

as shown in Figure 2–8.

y(i + 1)

(1 – p1) p2

u (i + 1)

Z – 1

Figure 2–8. First-Order Correction Filter

The difference equation for this correction filter is:

(4)

y(i + 1) = p2 ⋅ (1 – p1) ⋅ u(i + 1) + p1 ⋅ y(i)

where the constant p1 determines the pole locations.

The resulting squared magnitude transfer function is:

| H (f) | 2 =

(p2)2

V (1–p1)2

1 – 2

V p1 V cos (2p f/fs) + (p1)2

(5)

2.28 Correction Results

Table 2-6 shows the optimum p values and the corresponding correction results for 8000-Hz and 9600-Hz

sampling rates (see Figures 5 – 8, 5 –9, and 5 –10).

TLC32046MFKB Datasheet(PDF) 29 Page - Texas Instruments

TLC32046MFKB Datasheet(HTML) 29 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56

Datasheet Download

Link URL