AD9775EB AD [Analog Devices], AD9775EB Datasheet - Page 28

• Manufacturer Part Number: AD9775EB
• Description: 14-Bit, 160 MSPS 2X/4X/8X Interpolating Dual TxDAC+ D/A Converter
• Manufacturer: AD [Analog Devices]

AD9775
MODULATION, INTERPOLATION = 4×
With Control Register 01h, Bits 7 and 6 set to “10,” the inter-
polation rate of the AD9775 is 4×. Modulation is achieved by
multiplying successive samples at the interpolation filter output
Figure 27a. 4 × Interpolation, Modulation Disabled
Figure 27b. 4 × Interpolation, Modulation = f
–100
–100
–20
–40
–60
–80
–20
–40
–60
–80
0
0
0
0
Figure 27. Effect of Digital Modulation on DAC Output Spectrum, Interpolation = 4 ×
1
1
f
f
OUT
OUT
(
(
2
2
f
f
DATA
DATA
)
)
3
3
DAC
4
/2
4
–28–
by the sequence (0, 1, 0, –1). Figures 27a–27d represent the
spectral response of the AD9775 DAC output with 4× interpo-
lation in the various modulation modes to a narrow band
baseband signal.
Figure 27d. 4 × Interpolation, Modulation = f
Figure 27c. 4 × Interpolation, Modulation = f
–100
–100
–20
–40
–60
–80
–20
–40
–60
–80
0
0
0
0
1
1
f
f
OUT
OUT
(
(
2
2
f
f
DATA
DATA
)
)
3
3
DAC
DAC
REV. 0
/4
4
4
/8