UG-963 EVAL-ADF4152HVEB1Z User Guide
Rev. 0 | Page 4 of 20
EVALUATION BOARD HARDWARE
The EVAL-ADF4152HVEB1Z schematics are shown in Figure 8,
Figure 9, Figure 10, and Figure 11. The silkscreen of the
evaluation board is shown in Figure 16.
POWER SUPPLIES
Two separate supply voltages are required for the evaluation
board.
•Supply the banana connectors with 30 V. This powers the
LM317LDG regulator, which provides a regulated 29 V to
VP(the charge pump supply of the ADF4152HV) and 12 V
for the DCYS100200-12 VCO supply (VVCO).
•The test point labeled +5V must be supplied with 5 V, as
shown in Figure 7. The 5 V powers high precision, low
noise ADP150AUJZ-3.3 linear regulators to provide 3.3 V
to VDD on the board (which supplies the ADF4152HV AVDD,
DVDD, and SDVDD pins), to VOUT (which supplies the
ADF4152HV pull-up supply of the RF outputs), and to the
ADL5541 buffer, which improves phase frequency detector
(PFD) spur levels at the VCO output.
The D3 LED indicates when the ADF4152HV is powered.
INPUT SIGNALS
The reference signal is necessary for proper operation of the
synthesizer. It can be sourced from a provided TCXO or from
an external generator, which can be connected to the REFIN
edge mount connector. To us e an external reference generator,
it is necessary to remove R101 and R100 to disconnect the
TCXO from the reference input and from the supply. R102 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 local oscillator (LO) generation are
inserted on the board. The PLL is composed of the ADF4152HV
synthesizer, a fourth-order passive loop filter, and the octave range
VCO. The loop filter is inserted between the charge pump output
and the VCO input, as shown in Figure 11. If replacing the VCO, a
VCO in a T package (or similar) must be used. The VCO output is
available at the edge mount SMA connector, VCO_I/O, and the
differential RF output of the device is connected to the
RFOUT+ and RFOUT− edge mount SMA connectors.
A buffer, the ADL5541, is placed between the VCO output and
the ADF4152HV RFIN+ pin, which significantly lowers the PFD
spur levels seen at the VCO output below −110 dBc. If the PFD
spur level measured on the VCO output without a buffer is
sufficient (approximately −80 dBc) or if the output signal is
taken only from the RF output pins of the ADF4152HV and not
from the VCO output, the ADL5541 is not needed and can be
bypassed.
The device is quite sensitive to impedance unbalance. If only
one port of the differential pair is used, the other must be
terminated with a 50 Ω load. The external VCO output must
also be terminated in a 50 Ω load.
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 20 kHz
bandwidth at ICP = 300 μA, and an octave range VCO with a
1 GHz to 2 GHz frequency range. To test the performance of the
device for a different frequency range and a different loop filter, the
relevant components on the board must be changed.
Note that the DCYS100200-12 VCO tuning sensitivity decreases
as the tuning voltage increases (see Figure 2). To maintain a
constant loop filter bandwidth, increase the charge pump value
to the maximum of 384 µA for frequencies greater than
approximately 1.8 GHz.
Figure 2. VCO Tuning Sensitivity (KV) vs. Tuning Voltage for DCYS100200-12 VCO
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.
External VCO Option
Optionally, an external VCO can be used. In this case, it is
necessary to remove R32 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.
V
TUNE
(V)
K
V
(MHz/V)
70
65
60
50
55
40
45
30
35
20
25
10
15
02 4 6 8 10 12 14 16 18 20 22 24 26 28
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