AD9653BCPZ-125 Analog Devices, AD9653BCPZ-125 Datasheet - Page 28

• Manufacturer Part Number: AD9653BCPZ-125
• Description: the ad9653 is a quad, 16-bit, 125 msps analog-to-digital converter (adc) with an...
• Manufacturer: Analog Devices

AD9653
An example of the LVDS output using the ANSI-644 standard
(default) data eye and a time interval error (TIE) jitter histo-
gram with trace lengths less than 24 inches on standard FR-4
material is shown in Figure 73.
Figure 73. Data Eye for LVDS Outputs in ANSI-644 Mode with Trace Lengths
Less than 24 Inches on Standard FR-4 Material, External 100 Ω Far-End
–100
–200
–300
–400
–500
500
400
300
200
100
Figure 72. LVDS Output Timing Example in Reduced Range Mode
7k
6k
5k
4k
3k
2k
1k
200ps
0
0
D0 400mV/DIV
D1 400mV/DIV
DCO 400mV/DIV
FCO 400mV/DIV
–0.8ns
EYE: ALL BITS
250ps
–0.4ns
300ps
Termination Only
350ps
0ns
400ps
0.4ns
ULS: 7000/400354
450ps
4ns/DIV
0.8ns
500ps
Rev. 0 | Page 28 of 40
Figure 74 shows an example of trace lengths exceeding 24 inches
on standard FR-4 material. Notice that the TIE jitter histogram
reflects the decrease of the data eye opening as the edge deviates
from the ideal position.
It is the user’s responsibility to determine if the waveforms
meet the timing budget of the design when the trace lengths
exceed 24 inches. Additional SPI options allow the user to further
increase the internal termination (increasing the current) of all
four outputs to drive longer trace lengths. This can be achieved
by programming Register 0x15. Even though this produces
sharper rise and fall times on the data edges and is less prone to
bit errors, the power dissipation of the DRVDD supply increases
when this option is used.
The format of the output data is twos complement by default.
An example of the output coding format can be found in Table 12.
To change the output data format to offset binary, see the
Memory Map section.
Data from each ADC is serialized and provided on a separate
channel in two lanes in DDR mode. The data rate for each serial
stream is equal to 16 bits times the sample clock rate, with a
maximum of 500 Mbps/lane [(16 bits × 125 MSPS)/(2 × 2) =
500 Mbps/lane]. The lowest typical conversion rate is 20 MSPS.
See the Memory Map section for details on enabling this feature.
Figure 74. Data Eye for LVDS Outputs in ANSI-644 Mode with Trace Lengths
Greater than 24 Inches on Standard FR-4 Material, External 100 Ω Far-End
–100
–200
–300
–400
–500
500
400
300
200
100
12k
10k
–800ps –600ps –400ps –200ps
8k
6k
4k
2k
0k
0
–0.8ns
EYE: ALL BITS
–0.4ns
Termination Only
0ns
0ps
0.4ns
200ps
ULS: 8000/414024
Data Sheet
400ps
–0.8ns
600ps