AD9148BPCZ AD [Analog Devices], AD9148BPCZ Datasheet - Page 52

• Manufacturer Part Number: AD9148BPCZ
• Description: Quad 16-Bit,1 GSPS, TxDAC+ Digital-to-Analog Converter
• Manufacturer: AD [Analog Devices]

AD9148
Half-Band Filter 1 (HB1)
HB1 has four modes of operation, as shown in Figure 63. 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 or not the input signal is modulated by
the filter.
As is shown in Figure 63, 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 18 summarizes the HB1 modes.
Table 18. 2× Interpolation Filter Modes (Register 0x1C to
Register 0x1E)
Interpolation
Factor
2
2
2
2
Figure 64 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 19 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 63. 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
0
−f
f
(f
f
f
2.0
DAC
DAC
CENTER
DAC
DAC
Rev. PrA | Page 52 of 73
/4
/2
)
/4
Table 19. 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 65 and
Figure 66. 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 64. Pass-Band Detail of HB1
0.08
Figure 65. HB2, Even Filter Modes
0.4
IN1
Preliminary Technical Data
)
0.12
0.6
MODE 2
0.16
Pass-Band
Flatness (dB)
0.001
0.0012
0.0033
0.0076
0.0271
0.1096
0.8
0.20
(×
(×
1.0
f
f
IN2
IN1
0.24
)
MODE 4
)
1.2
0.28
1.4
0.32
Stop-Band
Rejection (dB)
85
80
70
60
50
40
1.6
MODE 6
0.36
1.8
0.40
2.0