AD9122 Analog Devices, AD9122 Datasheet - Page 40

• Manufacturer Part Number: AD9122
• Manufacturer: Analog Devices

Specifications of AD9122

• 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: LVDS,Par

AD9122
The available signal bandwidth for 8× interpolation vs. output
frequency varies between 50% and 80% of the input data rate,
as shown in Figure 59. Note that in 8× interpolation mode,
f
eight times from dc to f
Table 20. Recommended Interpolation Filter Modes (Register 0x1C Through Register 0x1E)
Interpolation Factor
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
4
4
4
4
4
4
4
4
2
2
2
2
1
2
3
DAC
When HB1 Mode 1 or Mode 3 is used, enabling premodulation provides an additional frequency translation of the input signal by f
input signal in the filter pass band.
This configuration was used in the 8× interpolation without NCO example (see the 8× Interpolation Without NCO section).
This configuration was used in the 4× interpolation with NCO example (see the 4× Interpolation with NCO section).
2
3
Figure 59. Signal Bandwidth vs. Center Frequency of the Output Signal,
= 8 × f
0.8
0.6
0.5
DATA
0.1
HB1, HB2, AND HB3
; therefore, the data shown in Figure 59 repeats
0.25
DAC
8× Interpolation
0.4
.
f
0.50
OUT
/
f
DATA
0.6
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)
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)
00 (Mode 0)
01 (Mode 1)
10 (Mode 2)
11 (Mode 3)
0.75
0.9
HB2[5:0]
000000
001001
010010
011011
100100
101101
110110
111111
000000
001001
010010
011011
100100
101101
110110
111111
000000
001001
010010
011011
100100
101101
110110
111111
Bypass
Bypass
Bypass
Bypass
1.00
Filter Modes
Rev. B | Page 40 of 60
HB3[5:0]
000000
000000
001001
001001
010010
010010
011011
011011
100100
100100
101101
101101
110110
110110
111111
111111
Bypass
Bypass
Bypass
Bypass
Bypass
Bypass
Bypass
Bypass
Bypass
Bypass
Bypass
Bypass
DETERMINING INTERPOLATION FILTER MODES
Table 20 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 20.
DATA
), the filter configuration that comes closest to matching
f
DC
DC
f
f
2f
2f
3f
3f
4f
4f
5f
5f
6f
6f
7f
7f
DC
DC
f
f
2f
2f
3f
3f
DC
DC
f
f
DATA
DATA
DATA
DATA
DATA
DATA
SIGNAL
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Modulation
DATA
/2, which centers a baseband
f
0
f
f
3f
2f
5f
3f
7f
4f
9f
5f
11f
6f
13f
7f
15f
0
f
f
3f
2f
5f
3f
7f
0
f
f
3f
DATA
DATA
DATA
DATA
DATA
DATA
CENTER
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
/2
/2
/2
/2
/2
/2
/2
/2
/2
/2
/2
Shift
/2
/2
/2