AD9775-EB Analog Devices, Inc., AD9775-EB Datasheet - Page 34

• Manufacturer Part Number: AD9775-EB
• Description: 14-bit, 160 Msps, 2?/4?/8? Interpolating Dual Txdac+ Digital-to-analog Converter
• Manufacturer: Analog Devices, Inc.

AD9775
MODULATION, INTERPOLATION = 4×
With Control Register 0x01, Bit 7 and Bit 6 set to 10, the
interpolation rate of the AD9775 is 4×. Modulation is achieved
by multiplying successive samples at the interpolation filter
output by the sequence (0, +1, 0, −1).
The Effects of the Digital Modulation on the DAC Output Spectrum, Interpolation = 4×
–100
–100
–20
–40
–60
–80
–20
–40
–60
–80
0
0
0
0
Figure 67. 4× Interpolation, Modulation Disabled
Figure 68. 4× Interpolation, Modulation = f
1
1
f
f
OUT
OUT
(×
(×
2
2
f
f
DATA
DATA
)
)
3
3
DAC
/4
4
4
Rev. E | Page 34 of 56
Figure 67 through Figure 70 represent the spectral response of
the AD9775 DAC output with 4× interpolation in the various
modulation modes to a narrow-band baseband signal.
–100
–100
–20
–40
–60
–80
–20
–40
–60
–80
0
0
0
0
Figure 69. 4× Interpolation, Modulation = f
Figure 70. 4× Interpolation, Modulation = f
1
1
f
f
OUT
OUT
(×
(×
2
2
f
f
DATA
DATA
)
)
3
3
DAC
DAC
/2
/8
4
4