Texas Instruments LMX2594PSEVM User manual

User’s Guide
LMX2594PSEVM Evaluation Instructions
ABSTRACT
The LMX2594PSEVM uses two LMX2594 synthesizers to generate two phase-coherent outputs with very fine
phase adjustment capability. The outputs of the synthesizers can also be combined to produce lower noise and
jitter than is possible with just one.
The LMX2594 is a high-performance, wideband synthesizer that can generate any frequency from 10 MHz to 15
GHz without using an internal doubler, thus eliminating the need for sub-harmonic filters.
Table of Contents
1 LMX2594PSEVM Evaluation Module.....................................................................................................................................3
1.1 Evaluation Module Contents.............................................................................................................................................. 3
1.2 Evaluation Setup Requirement.......................................................................................................................................... 3
1.3 Resources.......................................................................................................................................................................... 3
2 Setup........................................................................................................................................................................................4
2.1 Connection Diagram.......................................................................................................................................................... 4
2.2 Power Supply..................................................................................................................................................................... 4
2.3 Reference Clock.................................................................................................................................................................4
2.4 SYNC Input........................................................................................................................................................................ 4
2.5 RF Output...........................................................................................................................................................................4
2.6 Programming......................................................................................................................................................................4
2.7 Evaluation Software........................................................................................................................................................... 5
3 Typical Measurement..............................................................................................................................................................6
3.1 Category 3 Synchronization............................................................................................................................................... 6
3.2 Phase Noise Improvement.................................................................................................................................................7
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4 Schematic................................................................................................................................................................................9
5 PCB Layout and Layer Stack-up..........................................................................................................................................11
5.1 PCB Layer Stack-Up........................................................................................................................................................ 11
5.2 PCB Layout...................................................................................................................................................................... 11
6 Bill of Materials..................................................................................................................................................................... 13
7 EVM Modification..................................................................................................................................................................14
8 Troubleshooting Guide.........................................................................................................................................................15
9 Reference PRO......................................................................................................................................................................16
9.1 Output Frequency Selection.............................................................................................................................................16
9.2 Output Format Selection.................................................................................................................................................. 17
9.3 Typical Output Characteristics......................................................................................................................................... 18
9.4 Firmware Update..............................................................................................................................................................18
Trademarks
PLLatinum™ is a trademark of Texas Instruments.
Windows® is a registered trademark of Microsoft Corporation.
All trademarks are the property of their respective owners.
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1 LMX2594PSEVM Evaluation Module
1.1 Evaluation Module Contents
The following is included in the package:
• One LMX2594PSEVM board (DC193-001).
• One Reference PRO board (SV601349).
• One USB cable.
• One 10-pin ribbon cable.
1.2 Evaluation Setup Requirement
The evaluation requires the following hardware and software:
• A DC power supply
• A spectrum analyzer or a signal analyzer
• A PC running Windows® 7 or more recent version
• An oscilloscope
• A high quality signal generator
• Texas Instruments Clocks and Synthesizers TICS Pro software
• Texas Instruments PLLatinum™ Simulator Tool (optional)
1.3 Resources
Related evaluation and development resources include:
•LMX2594 data sheet
•TICS Pro software
•PLLatinum Simulator Tool (PLL Sim)
•Reference PRO design file
• Reference designs:
–TIDA-01410
–TIDA-01346
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2 Setup
2.1 Connection Diagram
Figure 2-1. Connection Diagram
2.2 Power Supply
Apply 3.6 V to Vcc SMA connector. Acceptable supply voltage range is 3.5 V to 5 V. The maximum current
consumption in the most extreme configuration must not exceed 1200 mA. The onboard LDOs will provide a
3.3-V supply to the LMX2594 devices.
2.3 Reference Clock
Connect a low jitter reference clock to the OSCin SMA connector. This clock is evenly distributed to both
LMX2594 devices. If a sine wave clock is used, 8 dBm or more input power is suggested.
2.4 SYNC Input
In category 1 and 2 phase synchronization, the timing of the SYNC signal is not critical. This SYNC signal can
be generated from the Reference Pro board. In category 3 phase synchronization, the SYNC signal has to be
carefully aligned with the reference clock of the synthesizers. This SYNC signal shall be provided externally to
the SYNC SMA connector.
2.5 RF Output
Each LMX2594 device has two RF outputs, but only RFoutA is used. By default, RFoutAP pin is connected to
the SMA connector while the RFoutAM pin is terminated onboard. This is the default configuration to measure
the phases between the outputs of the LMX2594 devices. With some modification to the EVM, the sum of the
two LMX2594 devices output can be obtained from the SumRFout SMA connector. See Section 7 for more
information on EVM modification.
2.6 Programming
Connect the ribbon cable from the Reference PRO to the LMX2594PSEVM.
Connect the USB cable from a PC to the USB port on the Reference PRO board. This provides a power
supply to the Reference PRO board and communication with the TICS Pro software. A firmware update may be
required. See Section 9.4 for details.
The two LMX2594 devices share the uWIRE socket but only one device can be programmed at a time. Make
sure that only one of the DIP switches is in the ON position at a time.
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Figure 2-2. uWIRE Switches
2.7 Evaluation Software
Download and install TICS Pro to a PC. Run the software and follow the following steps to get started.
1. Go to Select Device → PLL + VCO → LMX2594.
2. Go to Default Configuration → Default Mode.
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3 Typical Measurement
3.1 Category 3 Synchronization
Use the flow chart in the data sheet to determine the phase synchronization category. If it is a category 3
synchronization, there is limitation to the reference clock frequency and the timing of the SYNC signal with
respect to the reference clock is critical. Shown below is a category 3 synchronization example.
Figure 3-1. Category 3 TICS Pro Configuration
If it is a category 3 synchronization, VCO_PHASE_SYNC should be checked to put the devices in SYNC mode.
After programming, the outputs from the two LMX2594 devices may not be phase-aligned.
Figure 3-2. Output Phases Before Synchronization
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A timing critical SYNC pulse is needed to trigger synchronization.
Figure 3-3. Timing Critical SYNC Pulse
Figure 3-4. Output Phases After Synchronization
3.2 Phase Noise Improvement
By combining the output of two synthesizers that are in-phase, a theoretical 3-dB phase noise benefit is possible
due to the output power being 6-dB higher while the noise power is only 3-dB higher.
To measure the combined phase noise, some modification to the EVM is needed. See Section 7 for details.
In Figure 3-5, the blue trace shown the phase noise of individual LMX2594 device while the black trace
respresented the phase noise of the combined signal.
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Figure 3-5. Combined Phase Noise
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4 Schematic
Figure 4-1. LMX2594PSEVM Schematic (Page 1)
Figure 4-2. LMX2594PSEVM Schematic (Page 2)
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Figure 4-3. LMX2594PSEVM Schematic (Page 3)
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5 PCB Layout and Layer Stack-up
5.1 PCB Layer Stack-Up
Top layer
RO4350B (Er = 3.66)
8 mil
GND layer
FR4 (Er = 4.2)
40 mil
FR4 (Er = 4.2)
8 mil
Bottom layer
62 mil
Power layer
Figure 5-1. PCB Layer Stack-Up
5.2 PCB Layout
Figure 5-2. Top Layer
Figure 5-3. GND Layer
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Figure 5-4. Power Layer
Figure 5-5. Bottom Layer
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6 Bill of Materials
Table 6-1. Bill of Materials
DESIGNATOR QUANTITY DESCRIPTION PART NUMBER MANUFACTURER
C1, C2, C3, C4 4 CAP, CERM, 10 µF, 16 V,
10%, X7R, 0805
EMK212BB7106KG-T Taiyo Yuden
C1_LF1, C1_LF2 2 CAP, CERM, 390 pF, 50 V,
5%, C0G/NP0, 0603
06035A391JAT2A AVX
C2_LF1, C2_LF2 2 CAP, CERM, 0.068 µF, 25 V,
10%, X7R, 0603
885012206070 Wurth Elektronik
C4_LF1, C4_LF2 2 CAP, CERM, 1800 pF, 50 V,
5%, C0G/NP0, 0603
GRM1885C1H182JA01D MuRata
C5, C8, C9, C10, C12, C22,
C23, C24, C26, C27, C33,
C35, C36, C37, C40, C41
16 CAP, CERM, 0.1 µF, 16 V,
5%, X7R, 0603
0603YC104JAT2A AVX
C6, C11, C20, C25, C34, C39 6 CAP, CERM, 1 µF, 16 V, 10%,
X7R, 0603
885012206052 Wurth Elektronik
C7, C16, C17, C18, C21,
C31, C32, C38
8 CAP, CERM, 10 µF, 10 V,
10%, X5R, 0603
GRM188R61A106KAALD MuRata
C13, C14, C15, C28, C29,
C30, C42, C43
8 CAP, CERM, 0.1 µF, 16 V,
10%, X7R, 0402
530L104KT16T AT Ceramics
C44, C45 2 CAP, CERM, 4.7 µF, 50 V,
X7R, 10%, 0805
CGA4J1X7R1H475K125AC TDK Corporation
D1, D2 2 LED, Green, SMD LTST-C190GKT Lite-On
J1, J2, J4 3 Connector, End launch SMA
50 ohm, TH
142-0761-881 Cinch Connectivity
J3, J5, J6 3 Connector, End launch SMA,
50 ohm, SMT
142-0701-851 Cinch Connectivity
L1, L2 2 Inductor, Multilayer, Air Core,
18 nH, SMD
LQG15HS18NJ02D MuRata
R1, R2, R4_LF1, R4_LF2,
R26, R30, R35
7 RES, 0, 5%, 0.1 W, 0603 CRCW06030000Z0EA Vishay-Dale
R2_LF1, R2_LF2 2 RES, 68, 5%, 0.1 W, 0603 CRCW060368R0JNEA Vishay-Dale
R3, R3_LF1, R3_LF2, R4,
R5, R7, R8, R10
8 RES, 18, 5%, 0.1 W, 0603 CRCW060318R0JNEA Vishay-Dale
R6, R9, R11, R14, R18, R27,
R28, R31, R32, R33, R36
11 RES, 12 k, 5%, 0.1 W, 0603 CRCW060312K0JNEA Vishay-Dale
R12, R13 2 RES, 330, 5%, 0.1 W, 0603 RC0603JR-07330RL Yageo
R15, R16, R19, R20 4 RES, 51, 5%, 0.1 W, 0603 CRCW060351R0JNEA Vishay-Dale
R17, R21, R22, R23, R24,
R25
6 RES, 50, 0.1%, 0.05 W, 0402 FC0402E50R0BST1 Vishay-Dale
R29, R34 2 RES, 22.1 k, 1%, 0.1 W, 0603 CRCW060322K1FKEA Vishay-Dale
S1, S2 2 Switch, SPST, Slide, Off-On,
4 Pos, SMD
219-4MST CTS Electrocomponents
TP1 1 Test Point, White, TH 5007 Keystone Electronics
U1, U2 2 15 GHz RF Synthesizer LMX2594RHAR Texas Instruments
U3 1 Power Splitter/Combiner,
50Ohm, 1.8 to 12.5 GHz
EP2C+ Minicircuits
U4, U5 2 1-A, Ultra-Low Noise LDO TPS7A9401DSCR Texas Instruments
uWire 1 Header (shrouded), 100 mil,
5x2, Gold, SMT
52601-S10-8LF FCI
C1, C2, C3, C4 4 CAP, CERM, 10 µF, 16 V,
10%, X7R, 0805
EMK212BB7106KG-T Taiyo Yuden
C1_LF1, C1_LF2 2 CAP, CERM, 390 pF, 50 V,
5%, C0G/NP0, 0603
06035A391JAT2A AVX
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7 EVM Modification
The default EVM configuration has the outputs of the LMX2594 devices connected to the RFout1 and RFout2
SMA connectors. To evaluate the phase noise improvement by summing the two outputs together, do the
following modifications.
• Move C13 to C13p
• Move C30 to C30p
Figure 7-1. EVM Modification for Phase Noise Reduction
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8 Troubleshooting Guide
If the EVM does not work as expected, use the following chart to identify potential root causes. Remember:
• Verify that the EVM is in working order before you make modifications to the EVM or change the default
settings
• Register readback requires the correct hardware and software setup.
• The POR current of the LMX2594PSEVM is approximately 400 mA.
Figure 8-1. Trouble Shooting Guide
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9 Reference PRO
The Reference PRO board is used to program the LMX2594PSEVM and provide a clean reference clock
to LMX2594PSEVM at the same time. The board has several control pins dedicated for control of output
format, output frequency, and output enable control. These control pins are configurable through the jumpers
by strapping the center pin to Vdd position or GND position. Connections from the Vdd position to the device
supply or from the GND position to the ground plane are connected by 1.5-kΩ resistors. By default, the board is
configured for 100-MHz LVPECL output. The power supply to Reference PRO is obtained from the PC through a
USB connection.
Figure 9-1. Reference PRO Board
9.1 Output Frequency Selection
Jumpers FS1 and FS0 are used to set the output frequency.
Table 9-1. Reference PRO Output Frequency Selection
FS1 FS0 OUTPUT FREQUENCY (MHz)
GND GND 100
GND NC 312.5
GND Vdd 125
NC GND 106.25
NC NC 156.25
NC Vdd 212.5
Vdd GND 62.5
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9.2 Output Format Selection
The OE pin is used to enable or disable the output.
The OS pin is used to bias internal drivers and change the output format.
Table 9-2. Reference PRO Output Format Selection
OE OS OUTPUT FORMAT
GND Don't Care Disabled
Vdd GND LVPECL
Vdd NC LVDS
Vdd Vdd HCSL
It is imperative to match the output termination passive components as shown in Table 9-3.
Table 9-3. Output Termination Configuration
OUTPUT FORMAT COUPLING COMPONENT VALUE
LVPECL AC (Default configuration) R15, R28 0 Ω
R26, R29 150 Ω
C24, C25 0.01 µF
R27, R30, R31 DNP
DC(1) R15, R28, C24, C25 0 Ω
R26, R27, R29, R30, R31 DNP
LVDS(2) AC R25, R27, R28, R30 0 Ω
R31 100 Ω
C24, C25 0.01 µF
R26, R29 DNP
DC R25, R27, R28, R30, C24, C25 0 Ω
R31 100 Ω
R26, R29 DNP
HCSL AC R15, R28 0 Ω
R26, R29 50 Ω
C24, C25 0.01 µF
R27, R30, R31 DNP
DC R25, R28, C24, C25 0 Ω
R26, R29 50 Ω
R27, R30, R31 DNP
(1) 50-Ω to VCC – 2-V termination is required on receiver.
(2) 100-Ω differential termination (R31) is provided onboard. Removing this termination is possible if the differential termination is available
on the receiver.
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Figure 9-2. Output Termination Schematic
9.3 Typical Output Characteristics
Figure 9-3. Default Output Phase Nosie Figure 9-4. Default Output Waveform
9.4 Firmware Update
Usually when the Reference PRO board is used at the first time, TICS Pro will request for a firmware update.
Simply follow the pop-up instructions to complete the update. This is necessary to ensure that the USB
connection between the PC and the Reference PRO board is properly set up, otherwise the programming to
LMX2594PSEVM will not be successful.
1. When you see this message, press the OK button.
Figure 9-5. Firmware Requirement
2. Next, follow the on-screen procedure.
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Figure 9-6. Firmware Loader
3. Find the BSL button next to the USB connector.
Figure 9-7. BSL Button
4. Follow the on-screen procedure until the Update Fireware pop-up appears.
Figure 9-8. Update Firmware
5. Press the Upgrade Firmware button to start the firmware upgrade. Press the Close button after the upgrade
is complete.
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Figure 9-9. Firmware Update Completed
6. Go to USB communications → Interface to check the USB connection in TICS Pro. Make sure the USB
Connected button is now green.
Figure 9-10. USB Communications
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