AD9146 datasheet(32/52 Pages) AD

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AD9146

Rev. 0 | Page 32 of 52

0.40

Figure 41 shows the pass-band filter response for HB1. In most

applications, the usable bandwidth of the filter is limited by the

image suppression provided by the stop-band rejection and not

by the pass-band flatness. Table 16 shows the pass-band flatness

and the stop-band rejection supported by the HB1 filter at dif-

ferent bandwidths.

0.02

–0.10

–0.08

–0.06

–0.04

–0.02

0.36

0.32

0.28

0.24

0.20

0.16

0.12

0.08

0.04

FREQUENCY (×

fIN1) (Hz)

Figure 41. Pass-Band Detail of HB1

Table 16. HB1 Pass-Band and Stop-Band Performance by

Bandwidth

Bandwidth (% of fIN1)

Pass-Band

Flatness (dB)

Stop-Band

Rejection (dB)

0.001

80.4

0.0012

81.2

0.0033

0.0076

83.6

0.0271

85.6

0.1096

Half-Band Filter 2 (HB2)

HB2 has eight modes of operation, as shown in Figure 42 and

Figure 43. The shape of the filter response is identical in each

of the eight modes. The eight modes are distinguished by two

factors: the filter center frequency and whether the input signal

is modulated by the filter.

–20

–40

–60

–80

–100

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

MODE 0

MODE 2

MODE 6

MODE 4

FREQUENCY (×

fIN2) (Hz)

Figure 42. HB2, Even Filter Modes

–20

–40

–60

–80

–100

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

MODE 1

MODE 3

MODE 7

MODE 5

FREQUENCY (×

fIN2) (Hz)

Figure 43. HB2, Odd Filter Modes

As shown in Figure 42 and Figure 43, the center frequency in

each mode is offset by one-fourth the input data rate (fIN2) of

the filter. Mode 0 through Mode 3 do not modulate the input

signal. Mode 4 through Mode 7 modulate the input signal by

fIN2. When operating in Mode 0 and Mode 4, the I and Q paths

operate independently and no mixing of the data between chan-

nels occurs. When operating in the other six modes, mixing of

the data between the I and Q paths occurs; therefore, the data

input to the filter is assumed to be complex. Table 17 summarizes

the HB2 modes.

Table 17. HB2 Filter Modes

Mode

fCENTER

fMOD

Input Data

None

Real or complex

fIN/4

None

Complex

fIN/2

None

Complex

3fIN/4

None

Complex

fIN

Real or complex

5fIN/4

fIN

Complex

3fIN/2

fIN

Complex

7fIN/4

fIN

Complex

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