AD9146 Analog Devices, AD9146 Datasheet - Page 34

• Manufacturer Part Number: AD9146
• Description: Dual, 16-Bit, 1230 MSPS, TxDAC+® Digital-to-Analog Converter
• Manufacturer: Analog Devices

Specifications of AD9146

• Resolution (bits): 16bit
• Dac Update Rate: 1.23GSPS
• Dac Settling Time: n/a
• Max Pos Supply (v): +3.47V
• Single-supply: No
• Dac Type: Current Out
• Dac Input Format: Byte,LVDS,Nibble

AD9146
Figure 44 shows the pass-band filter response for HB2. 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 18 shows the pass-band flatness
and stop-band rejection supported by the HB2 filter at different
bandwidths.
Table 19. Recommended Interpolation Filter Modes (Register 0x1C and Register 0x1D)
Interpolation Factor
4
4
4
4
4
4
4
4
2
2
2
2
1
input signal in the filter pass band.
When HB1 Mode 1 or Mode 3 is used, enabling premodulation provides an additional frequency translation of the input signal by f
–0.02
–0.04
–0.06
–0.08
–0.10
0.02
0
0
0.04
Figure 44. Pass-Band Detail of HB2
0.08
FREQUENCY (×
0.12
0.16
HB1[1:0]
00 (Mode 0)
01 (Mode 1)
10 (Mode 2)
11 (Mode 3)
00 (Mode 0)
01 (Mode 1)
10 (Mode 2)
11 (Mode 3)
00 (Mode 0)
01 (Mode 1)
10 (Mode 2)
11 (Mode 3)
f
IN2
0.20
) (Hz)
0.24
0.28
Filter Modes
0.32
HB2[5:0]
000000
001001
010010
011011
100100
101101
110110
111111
Bypass
Bypass
Bypass
Bypass
Rev. A | Page 34 of 56
Table 18. HB2 Pass-Band and Stop-Band Performance by
Bandwidth
Bandwidth (% of f
50
50.8
52.8
56
60
64.8
DATAPATH CONFIGURATION
Configuring the AD9146 datapath starts with the application
requirements of the input data rate, the interpolation ratio, the
output signal bandwidth, and the output signal center frequency.
Given these four parameters, the first step in configuring the
datapath is to verify that the device supports the bandwidth
requirements. The modes of the interpolation filters are then
chosen.
DETERMINING INTERPOLATION FILTER MODES
Table 19 shows the recommended interpolation filter settings
for a variety of filter interpolation factors, filter center frequencies,
and signal modulation. The interpolation modes were chosen
based on the final center frequency of the signal and by deter-
mining the frequency shift of the signal required. When these
parameters are known and put in terms of the input data rate
(f
is selected from Table 19.
DATA
), the filter configuration that comes closest to matching
f
DC
DC
f
f
2f
2f
3f
3f
DC
DC
f
f
DATA
DATA
DATA
DATA
SIGNAL
DATA
DATA
DATA
DATA
1
1
1
1
1
1
Modulation
IN2
)
Pass-Band
Flatness (dB)
0.001
0.0012
0.0028
0.0089
0.0287
0.1877
DATA
/2, which centers a baseband
f
0
f
f
3f
2f
5f
3f
7f
0
f
f
3f
DATA
DATA
DATA
DATA
CENTER
DATA
DATA
DATA
DATA
DATA
DATA
/2
/2
/2
/2
/2
/2
Shift
Data Sheet
Stop-Band
Rejection (dB)
85
80
70
60
50
40