AD9680 datasheet(61/99 Pages) AD

61 / 99 page

Data Sheet

AD9680

Rev. C | Page 59 of 97

HB2 Filter

The third decimate-by-2, half-band, low-pass FIR filter (HB2)

uses a 19-tap, symmetrical, fixed coefficient filter implementation

that is optimized for low power consumption. The HB2 filter is

only used when complex outputs (decimate by 4, 8, or 16) or

real outputs (decimate by 2, 4, or 8) are enabled; otherwise, the

filter is bypassed.

Table 21 and Figure 152 show the coefficients and response of

the HB2 filter.

Table 21. HB2 Filter Coefficients

HB2 Coefficient

Number

Normalized

Coefficient

Decimal Coefficient

(19-Bit)

C1, C19

0.000614

161

C2, C18

C3, C17

−0.005066

−1328

C4, C16

C5, C15

0.022179

5814

C6, C14

C7, C13

−0.073517

−19,272

C8, C12

C9, C11

0.305786

80,160

C10

0.500000

131,072

–120

–100

–80

–60

–40

–20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

NORMALIZED FREQUENCY (× π RAD/SAMPLE)

Figure 152. HB2 Filter Response

HB1 Filter

The fourth and final decimate-by-2, half-band, low-pass FIR

filter (HB1) uses a 55-tap, symmetrical, fixed coefficient filter

implementation, optimized for low power consumption. The

HB1 filter is always enabled and cannot be bypassed. Table 22

and Figure 153 show the coefficients and response of the HB1

filter.

–120

–100

–80

–60

–40

–20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

NORMALIZED FREQUENCY (× π RAD/SAMPLE)

Figure 153. HB1 Filter Response

Table 22. HB1 Filter Coefficients

HB1 Coefficient

Number

Normalized

Coefficient

Decimal Coefficient

(21-Bit)

C1, C55

−0.000023

−24

C2, C54

C3, C53

0.000097

102

C4, C52

C5, C51

−0.000288

−302

C6, C50

C7, C49

0.000696

730

C8, C48

C9, C47

−0.0014725

−1544

C10, C46

C11, C45

0.002827

2964

C12, C44

C13, C43

−0.005039

−5284

C14, C42

C15, C41

0.008491

8903

C16, C40

C17, C39

−0.013717

−14,383

C18, C38

C19, C37

0.021591

22,640

C20, C36

C21, C35

−0.033833

−35,476

C22, C34

C23, C33

0.054806

57,468

C24, C32

C25, C31

−0.100557

−105,442

C26, C30

C27, C29

0.316421

331,792

C28

0.500000

524,288

AD9680 Datasheet(PDF) 61 Page - Analog Devices

AD9680 Datasheet(HTML) 61 Page - Analog Devices

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 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

Datasheet Download

Link URL