AD9148 Analog Devices, AD9148 Datasheet - Page 52

• Manufacturer Part Number: AD9148
• Manufacturer: Analog Devices

Specifications of AD9148

• Resolution (bits): 16bit
• Dac Update Rate: 1GSPS
• Dac Settling Time: n/a
• Max Pos Supply (v): +3.47V
• Single-supply: No
• Dac Type: Current Out
• Dac Input Format: LVDS,Par

AD9148
Half-Band Filter 1 (HB1)
HB1 has four modes of operation, as shown in Figure 64. The
shape of the filter response is identical in each of the four modes.
The four modes are distinguished by two factors: the filter center
frequency and whether the filter modulates the input signal.
As is shown in Figure 64, the center frequency in each mode is
offset by ½ of the input data rate (f
Mode 1 do not modulate the input signal. Mode 2 and Mode 3
modulate the input signal by f
and Mode 2, the I and Q paths operate independently and no
mixing of the data between channels occurs. When operating
in Mode 1 and Mode 3, mixing of the data between the I and Q
paths occurs; therefore, the data input into the filter is assumed
complex. Table 19 summarizes the HB1 modes.
Table 19. 2× Interpolation Filter Modes (Register 0x1C to
Register 0x1E)
Interpolation
Factor
2
2
2
2
Figure 65 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 20 shows the pass-band flatness
and stop-band rejection the HB1 filter supports at different
bandwidths.
–100
–20
–40
–60
–80
0
0
MODE 0
0.2
0.4
Pre-Mod
0
1
0
1
Figure 64. HB1 Filter Modes
0.6
MODE 1
0.8
Filter Modes
IN1
(×
HB1
0
1
2
3
. When operating in Mode 0
1.0
f
IN1
IN1
)
MODE 2
) of the filter. Mode 0 and
1.2
HB2
Off
Off
Off
Off
1.4
1.6
MODE 3
HB3
Off
Off
Off
Off
1.8
2.0
f
(f
0
f
f
−f
DAC
DAC
CENTER
DAC
DAC
/4
/2
Rev. B | Page 52 of 72
)
/4
Table 20. HB1 Pass-Band and Stop-Band Performance by
Bandwidth
Bandwidth (% of f
80
80.4
81.2
82.0
83.6
85.6
Half-Band Filter 2 (HB2)
HB2 has eight modes of operation, as shown in Figure 66 and
Figure 67. 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.
–100
–0.02
–0.04
–0.06
–0.08
–0.10
–20
–40
–60
–80
0.02
0
0
0
0
MODE 0
0.04
0.2
Figure 65. Pass-Band Detail of HB1
0.08
Figure 66. HB2, Even Filter Modes
0.4
IN1
)
0.12
0.6
MODE 2
0.16
0.8
Pass-Band
Flatness (dB)
0.001
0.0012
0.0033
0.0076
0.0271
0.1096
0.20
(×
(×
1.0
f
IN2
f
IN1
0.24
)
MODE 4
)
1.2
0.28
1.4
0.32
Data Sheet
Stop-Band
Rejection (dB)
85
80
70
60
50
40
1.6
MODE 6
0.36
1.8
0.40
2.0