CN-0311 Datasheet, PDF (3/4 Pages) Analog Devices – Broadband, Low Error Vector Magnitude (EVM) Direct Conversion Transmitter Using LO Divide-by-2 Modulator

Circuit Note
CN-0311
R&S AMIQ
RF_OUTA+
ADF4351
EVALUATION BOARD
RF_OUTA–
IP IN QP QN
LOIP
ADL5385 EVALUATION BOARD
ADAPTED TO ACCEPT
RFOUT
DIFFERENTIAL LO INPUTS
LOIN
5V
SPECTRUM
ANALYZER
POWER SUPPLY
Figure 3. Sideband Suppression Measurement Test Setup (Simplified Diagram)
COMMON VARIATIONS
The PLL-to-modulator interface described is applicable to all
I/Q modulators that contain a 2XLO-based phase splitter. It is
also applicable to 2XLO-based I/Q demodulators, such as the
ADL5387.
CIRCUIT EVALUATION AND TEST
The CN-0311 uses the EVAL-ADF4351EB1Z and the ADL5385-
EVALZ for the evaluation of the described circuit, allowing for
quick setup and evaluation. The EVAL-ADF4351EB1Z uses
the standard ADF4351 programming software contained on the
CD that accompanies the evaluation board.
Equipment Needed
The following equipment is needed:
• A PC with a USB port that contains Windows® XP, Vista, or
Windows 7
• The EVAL-ADF4351EB1Z evaluation board
• The ADL5385-EVALZ evaluation board,
• ADF4351 programming software
• Power supplies (5 V, 500 mA)
• An I-Q signal source, such as a Rohde & Schwarz AMIQ
• A spectrum analyzer
Also, see the UG-435 User Guide for the EVAL-ADF4351EB1Z
evaluation board, the ADF4351 data sheet, and the ADL5385
data sheet.
Getting Started
A description of the circuit, the schematic, and a block diagram
of the test setup is detailed within the CN-0311 (see Figure 1 and
Figure 3). The UG-435 user guide details the installation and use of
the EVAL-ADF4351EB1Z evaluation software. The UG-435 also
contains the board setup instructions, and the board schematic,
layout, and bill of materials. The ADL5385-EVALZ board
schematic, block diagram, bill of materials, layout, and assembly
information is included in the ADL5385 data sheet. See the
ADF4351 data sheet and ADL5385 data sheet for device
information.
Functional Block Diagram
The functional block diagram of the described test setup is
shown in Figure 3.
Setup and Test
After setting up the equipment, use standard RF test methods to
measure the sideband suppression of the circuit.
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