AD9779 Analog Devices, AD9779 Datasheet - Page 32

• Manufacturer Part Number: AD9779
• Description: Dual 16-Bit, 1 GSPS, Digital-to-Analog Converter
• Manufacturer: Analog Devices

Specifications of AD9779

• Resolution (bits): 16bit
• Dac Update Rate: 1GSPS
• Dac Settling Time: n/a
• Max Pos Supply (v): +3.47V
• Single-supply: Yes
• Dac Type: Current Out
• Dac Input Format: Par

AD9776/AD9778/AD9779
With the interpolation filter and modulator combined, the
incoming signal can be placed anywhere within the Nyquist
region of the DAC output sample rate. When the input signal is
complex, this architecture allows modulation of the input signal
to positive or negative Nyquist regions (see Table 17).
The Nyquist regions of up to 4× the input data rate can be seen
in Figure 60.
Figure 57, Figure 58, and Figure 59 show the low-pass response
of the digital filters with no modulation. By turning on the
modulation feature, the response of the digital filters can be
tuned to anywhere within the DAC bandwidth. As an example,
Figure 61 to Figure 67 show the nonshifted mode filter responses
(refer to Table 17 for shifted/nonshifted mode filter responses).
Figure 59. 8× Interpolation, Low-Pass Response to ±4× Input Data Rate
Figure 61. Interpolation/Modulation Combination of 4 f
–100
–100
–10
–20
–30
–40
–50
–60
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
–4×
10
10
0
0
–8
–4
–4
–7
–3×
–6
–3
–3
(Dotted Lines Indicate 1 dB Roll-Off)
–5
–2×
–4
–2
–2
Figure 60. Nyquist Zones
–3
–1×
f
f
OUT
–2
OUT
–1
–1
–1
(× Input Data Rate)
(× Input Data Rate)
DC
1
0
0
2
1×
3
1
1
4
2×
5
2
2
6
3×
7
DAC
8
3
3
4×
/8 Filter
4
4
Rev. A | Page 32 of 56
Figure 62. Interpolation/Modulation Combination of −3 f
Figure 63. Interpolation/Modulation Combination of −2 f
Figure 64. Interpolation/Modulation Combination of −1 f
–100
–100
–100
–10
–20
–30
–40
–50
–60
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
10
10
10
0
0
0
–4
–4
–4
–3
–3
–3
–2
–2
–2
f
f
f
OUT
OUT
OUT
–1
–1
–1
(× Input Data Rate)
(× Input Data Rate)
(× Input Data Rate)
0
0
0
1
1
1
2
2
2
DAC
DAC
DAC
3
3
3
/8 Filter
/8 Filter
/8 Filter
4
4
4