AD9411/PCB Analog Devices Inc, AD9411/PCB Datasheet - Page 21

• Manufacturer Part Number: AD9411/PCB
• Manufacturer: Analog Devices Inc

Specifications of AD9411/PCB

• Lead Free Status / Rohs Status: Not Compliant

EVALUATION BOARD
The AD9411 evaluation board offers an easy way to test the
AD9411 in LVDS mode. It requires a clock source, an analog
input signal, and a 3.3 V power supply. The clock source is
buffered on the board to provide the clocks for the ADC,
latches, and a data-ready signal. The digital outputs and output
clocks are available at a 40-pin connector, P23. The board has
several different modes of operation and is shipped in the
following configurations:
•
•
•
POWER CONNECTOR
Power is supplied to the board via a detachable 12-lead power
strip (three 4-pin blocks).
Table 8. Power Connector, LVDS Mode
AVDD
DRVDD
VDL
VCLK/V_XTAL
EXT_VREF
1
2
ANALOG INPUTS
The evaluation board accepts a 1.3 V p-p analog input signal
centered at ground at SMB connector J4. This signal is
terminated to ground through 50 Ω by R16. The input can be
alternatively terminated at the T1 transformer secondary by
R13 and R14. T1 is a wideband RF transformer that provides a
single-ended-to-differential conversion, allowing the ADC to be
driven differentially, which minimizes even-order harmonics.
An optional second transformer, T2, can be placed following T1
if desired. This provides some performance advantage (~1 dB to
2 dB) for high analog input frequencies (>100 MHz). If T2 is
placed, cut the two shorting traces at the pads. The analog
signal can be low-pass filtered by R41, C12 and R42, C13 at the
ADC input. The footprint for transformer T2 can be modified
to accept a wideband differential amplifier (AD8351) for low
frequency applications where gain is required. See the PCB
schematic for more information.
AVDD, DRVDD, and VDL are the minimum required power connections.
LVEL16 clock buffer can be powered from AVDD or VCLK at E47 jumper.
1
Offset binary
Internal voltage reference
Full-scale adjust = low
3.3 V
1
3.3 V
1
3.3 V
2
Supply for Clock Buffer/Optional XTAL
Analog Supply for ADC (350 mA)
Output Supply for ADC (50 mA)
Supply for Support Logic
Optional External Reference Input
Rev. A | Page 21 of 28
GAIN
Full scale is set at E17–E19, E17–E18 sets S5 low, full scale =
1.5 V differential; E17–E19 sets S5 high, full scale = 0.75 V
differential. Best performance is obtained at 1.5 V full scale.
CLOCK
The clock input is terminated to ground through 50 Ω resistor
at SMB connector J5. The input is ac-coupled to a high speed
differential receiver (LVEL16) that provides the required low
jitter, fast edge rates needed for optimum performance. J5 input
should be > 0.5 V p-p. Power to the LVEL16 is set at Jumper
E47. E47–E45 powers the buffer from AVDD; E47–E46 powers
the buffer from VCLK/V_XTAL.
VOLTAGE REFERENCE
The AD9411 has an internal 1.23 V voltage reference. The ADC
uses the internal reference as the default when Jumpers E24–E27
and E25–E26 are left open. The full scale can be increased by
placing an optional resistor (R3). The required value varies with
the process and needs to be tuned for the specific application.
Full scale can similarly be reduced by placing R4; tuning is
required here as well. An external reference can be used by
shorting the SENSE pin to 3.3 V (place Jumper E26–E25).
Jumper E27–E24 connects the ADC VREF pin to the
EXT_VREF pin at the power connector.
DATA FORMAT SELECT
Data format select (DFS) sets the output data format of the
ADC. Setting DFS (E1–E2) low sets the output format to be
offset binary; setting DFS high (E1–E3) sets the output to twos
complement.
DATA OUTPUTS
The ADC LVDS digital outputs are routed directly to the
connector at the card edge. Resistor pads placed at the output
connector allow for termination if the connector receiving logic
lack the differential termination for the data bits and DCO.
Each output trace pair should be terminated differentially at
the far end of the line with a single 100 ohm resistor.
CLOCK XTAL
An optional XTAL oscillator can be placed on the board to
serve as a clock source for the PCB. Power to the XTAL is
through the VCLK/VXTAL pin at the power connector. If an
oscillator is used, ensure proper termination for best results.
The board was tested with a Valpey Fisher VF561 and a Vectron
JN00158-163.84.
AD9411