UG-804
EV-ADF4355-2SD1Z User Guide
Rev. 0 | Page 4 of 18
EVALUATION BOARD HARDWARE
The
EV-ADF4355-2SD1Z
requires the
SDP-S
platform that uses
the
EVAL-SDP-CS1Z
. (
SDP-B
is not recommended.)
The
EV-ADF4355-2SD1Z
schematics are shown in Figure 7,
Figure 8, and Figure 9. The silkscreens for the evaluation board
are shown in Figure 10 and Figure 11.
POWER SUPPLIES
The board is powered by a 6 V power supply connected to the
red and black banana connectors. Connect the red connector to
a 6 V power supply and the black connector to ground.
The power supply circuitry allows the user two or three separate
low dropout (LDO) regulators to feed the
ADF4355-2
(using
fewer LDO regulators increases the risk of spur contaminated
dc feeds).
The charge pump and VCO supply pins are driven from a
5 V
ADM7150
high performance, low noise regulator. The
remaining supplies are powered from 3.3 V
ADM7150
high
performance, low noise regulator.
LED1 indicates when the
ADF4355-2
is powered on. Use
Switch S1 to switch the 6 V to the board on and off.
RF OUTPUT
The
EV-ADF4355-2SD1Z
has two pairs of SMA output
connectors: /RFOUTA− and /RFOUTB−
(differential outputs). Because they are sensitive to impedance
mismatch, connect the RF outputs to equal load impedances.
If only one port of a differential pair is used, terminate the
complementary port with an equal load terminator (in general,
a 50 Ω terminator).
LOOP FILTER
The loop filter schematic is included in the board schematic in
Figure 7. Figure 3 shows the loop filter component placements.
For lowest rms phase noise, use the following components (that
are inserted on the evaluation board) with a 0.9 mA charge
pump current:
C60 = 1.2 nF, C59 = 33 nF, C61 = 390 pF, C73 = 10 pF
R14 = 1 kΩ, R17 = 3.3 kΩ
Narrower loop filter bandwidths have lower spurious signals.
Figure 3. Loop Filter Placement
REFERENCE SOURCE
The evaluation board contains a 122.88 MHz differential output
TCXO from Vectron International. If preferred, the user may
supply either a single-ended or differential reference input to
REFINA/REFINB SMA connectors. When using an external
reference, remove R12 to disconnect the power rail to the
TCXO.
To use a single-ended REFINx, connect a low noise 122.88 MHz
reference source to SMA REFINB, and connect a 50 Ω terminator
to SMA REFINA. Remove Resistor R27 (100 Ω). To use a
differential REFINx, connect the differential signal to SMA
REFINA and SMA REFINB. The differential REFINA/REFINB
SMA connectors can operate to a 500 MHz input frequency.
In the schematic shown in Figure 7, the REF
IN
A pin of U1
(
ADF4355-2
) is connected to SMA REFINB, and the REF
IN
B
pin of U1 (
ADF4355-2
) is connected to SMA REFINA. This
schematic matches the evaluation board connections.
DEFAULT CONFIGURATION
All components necessary for local oscillator (LO) generation
are inserted on the board. This board is shipped with the
ADF4355-2
synthesizer with an integrated VCO, a differential
122.88 MHz reference TCXO, and a 20 kHz loop filter (I
CP
=
0.9
mA).
RVTUNE
R5
C73
RCPOUT
R17
RP
IN
18
C60
C59
R14
C61
R1
12941-
002
