UG-380
Evaluation Board User Guide
Rev. 0 | Page 4 of 24
EVALUATION BOARD HARDWARE
The
schematics are shown in Figure 23,
Figure 24, Figure 25 and Figure 26. The silkscreen of the
evaluation board is shown in Figure 2.
POWER SUPPLIES
The board is powered from external banana connectors. The
supply voltage should be 5.5 V. The power supply circuit uses
high precision, low noise
and
adjustable LDO regulators to provide 3.3 V
to V
DD
on the board (which supplies the ADF4151 AV
DD
, DV
DD
,
and SDV
DD
pins) and 5 V to the ADF4150 V
P
.
INPUT SIGNALS
The reference signal is necessary for proper operation of the
synthesizer. It can be sourced from a provided TCXO or an
external generator, which can be connected to the REFIN edge
mount connector. To use an external reference generator, it is
necessary to remove R1 and R2 to disconnect the TCXO from
the reference input and from the supply. R3 can be populated
with a 50 Ω resistor to adjust the impedance matching of the
evaluation board to the external reference source.
Digital SPI signals are supplied from the Cypress microcontrol-
ler, U6, which is used for communication with the USB port of
the PC.
OUTPUT SIGNALS
All components necessary for LO generation are inserted on
the board. The PLL is made up of the
fourth-order passive loop filter, and the VCO. The loop filter
must be inserted between the charge pump output and the
VCO input, as shown in Figure 26. If replacing the VCO, a
VCO in a T-package (or similar) must be used. The RF output
is available at the edge mount SMA connector, VCO_I/ O, and
the differential RF output of the part is connected to the
RFOUT+ and RFOUT− edge mount SMA connectors.
DEFAULT OPERATION SETTINGS
This board is shipped with a TCXO that provides a reference
frequency of 25 MHz, a fourth-order low-pass filter with 30 kHz
bandwidth at I
CP
= 2.325 mA, and a VCO with a 1.7 GHz to
1.8 GHz frequency range. To test the performance of the part
for a different frequency range and different loop filter, the
relevant components on the board must be changed.
ADDITIONAL OPTIONS
The VVCO connector can be used as a test point to measure the
supply voltage of the VCO in its default configuration. It can
also be used to provide an external supply for the on-board
VCO; however, if an external supply for VCO is used, Resistor R31
must be removed to disconnect the connector from the output
of the on-board voltage regulator.
Optionally, an external VCO can be used. In this case, it is
necessary to remove R29 and insert a 0 Ω link at R46 to form a
connection between the loop filter output and the VTUNE
SMA edge mount connector. Remove R31 to disconnect the on-
board VCO from the power supply. Remove Resistor R26 to
disconnect the output of the on-board VCO from the RF signal
path, and replace Resistors R27 and R28 with 0 Ω links to
ensure operation of the VCO_I/O connector as an input from
an external VCO.
10552-
002
Figure 2. Evaluation Board Silkscreen
