AD9785BSVZ Analog Devices Inc, AD9785BSVZ Datasheet - Page 38

• Manufacturer Part Number: AD9785BSVZ
• Description: IC DAC 12BIT 800MSPS 100TQFP
• Manufacturer: Analog Devices Inc
• Series: TxDAC®r

Specifications of AD9785BSVZ

• Data Interface: Serial
• Number Of Bits: 12
• Number Of Converters: 2
• Voltage Supply Source: Analog and Digital
• Power Dissipation (max): 450mW
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 100-TQFP Exposed Pad, 100-eTQFP, 100-HTQFP, 100-VQFP
• Resolution (bits): 12bit
• Sampling Rate: 800MSPS
• Input Channel Type: Parallel
• Digital Ic Case Style: QFP
• No. Of Pins: 100
• Operating Temperature Range: -40°C To +85°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Settling Time: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

AD9785/AD9787/AD9788
DIGITAL DATAPATH
The AD9785/AD9787/AD9788 digital datapath consists of
three 2× half-band interpolation filters, a quadrature modulator,
and an inverse sinc filter. A 32-bit NCO provides the sine and
cosine carrier signals required for the quadrature modulator.
INTERPOLATION FILTERS
The AD9785/AD9787/AD9788 contain three half-band filters
that can be bypassed. This allows the device to operate with 2×,
4×, or 8× interpolation rates, or without interpolation. The
interpolation filters have a linear phase response. The coefficients
of the low-pass filters are given in Table 28, Table 29, and
Table 30. Spectral plots for the filter responses are shown in
Figure 55, Figure 56, and Figure 57.
In 2×, 4×, or 8× interpolation mode, the usable bandwidth of
the interpolation filter is 80% of the complex input data rate.
The usable bandwidth has a pass-band ripple of less than
0.0005 dB and a stop-band attenuation of greater than 85 dB.
The center frequency of the interpolation filter is set by the
NCO frequency tuning word (Register 0x0A, Bits [31:0]), so
baseband input signals are always centered in the interpolation
filter pass band.
Figure 55. 2× Interpolation, Low-Pass Response to ±4× Input Data Rate
–100
–10
–20
–30
–40
–50
–60
–70
–80
–90
10
0
–4
–3
(Dotted Lines Indicate 1 dB Roll-Off)
–2
f
OUT
–1
(×
Input Data Rate)
0
1
2
3
4
Rev. A | Page 38 of 64
Figure 56. 4× Interpolation, Low-Pass Response to ±4× Input Data Rate
Figure 57. 8× Interpolation, Low-Pass Response to ±4× Input Data Rate
–100
–100
–10
–20
–30
–40
–50
–60
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
10
10
0
0
–4
–4
–3
–3
(Dotted Lines Indicate 1 dB Roll-Off)
(Dotted Lines Indicate 1 dB Roll-Off)
–2
–2
f
f
OUT
OUT
–1
–1
(×
(×
Input Data Rate)
Input Data Rate)
0
0
1
1
2
2
3
3
4
4