AD9773-EB Analog Devices Inc, AD9773-EB Datasheet - Page 34

• Manufacturer Part Number: AD9773-EB
• Description: BOARD EVAL FOR AD9773
• Manufacturer: Analog Devices Inc
• Series: TxDAC®r

Specifications of AD9773-EB

• Rohs Status: RoHS non-compliant
• Number Of Dac's: 2
• Number Of Bits: 12
• Outputs And Type: 2, Differential
• Sampling Rate (per Second): 160M
• Data Interface: Parallel
• Settling Time: 11ns
• Dac Type: Current
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD9773

AD9773
MODULATION, NO INTERPOLATION
With Control Register 01h, Bit 7 and Bit 6 set to 00, the
interpolation function on the AD9773 is disabled. Figure 59 to
Figure 62 show the DAC output spectral characteristics of the
AD9773 in the various modulation modes, all with the
interpolation filters disabled. The modulation frequency is
determined by the state of Control Register 01h, Bits 5 and 4.
The tall rectangles represent the digital domain spectrum of a
baseband signal of narrow bandwidth.
The Effects of the Digital Modulation on the DAC Output Spectrum, Interpolation Disabled
–100
–100
–20
–40
–60
–80
–20
–40
–60
–80
0
0
0
0
Figure 59. No Interpolation, Modulation Disabled
Figure 60. No Interpolation, Modulation = f
0.2
0.2
0.4
0.4
f
f
OUT
OUT
( ×
( ×
f
f
DATA
DATA
0.6
0.6
)
)
0.8
0.8
DAC
/2
1.0
1.0
Rev. D | Page 34 of 60
By comparing the digital domain spectrum to the DAC SIN(x)/x
roll-off, an estimate can be made for the characteristics required
for the DAC reconstruction filter. Note also, per the previous
discussion on amplitude modulation, that the spectral com-
ponents (where modulation is set to f
factor of 2. In the situation where the modulation is f
modulated spectral components add constructively, and there is
no scaling effect.
–100
–100
–20
–40
–60
–80
–20
–40
–60
–80
0
0
0
0
Figure 61. No Interpolation, Modulation = f
Figure 62. No Interpolation, Modulation = f
0.2
0.2
0.4
0.4
f
f
OUT
OUT
( ×
( ×
f
f
DATA
DATA
0.6
0.6
)
)
S
/4 or f
S
/8) are scaled by a
0.8
0.8
DAC
DAC
/4
/8
S
/2, the
1.0
1.0