Texas Instruments LMX2615EVM-CVAL User manual

LMX2615EVM-CVAL Wideband 15-GHz
Synthesizer
User's Guide
Literature Number: SNAU218
November 2018

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Table of Contents
Contents
1 Evaluation Board Setup and Description ................................................................................ 4
2 Setting Up the Software........................................................................................................ 5
3 Bringing LMX2615 to a Lock State ......................................................................................... 6
4 Current Loop Filter Configuration .......................................................................................... 7
5 Typical Phase Noise............................................................................................................. 8
Appendix A Schematic................................................................................................................ 10
Appendix B Bill of Materials......................................................................................................... 11
Appendix C PCB Board Specifications.......................................................................................... 13
Appendix D Proper Jumper and Switch Positions .......................................................................... 18

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LMX2615EVM-CVAL Wideband 15-GHz Synthesizer
User's Guide
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LMX2615EVM-CVAL Wideband 15-GHz Synthesizer
Figure 1. LMX2615EVM-CVAL

+3.3 V
To Spectrum
Analyzer
50 :
Termination
100 MHz Input
Reference
Lock Detect
LED
Readback/
Lock Detect
Selector
Switch
Reference Pro
SPI interface
FS Switches
Power
Jumpers
Evaluation Board Setup and Description www.ti.com
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LMX2615EVM-CVAL Wideband 15-GHz Synthesizer
1 Evaluation Board Setup and Description
SPACER
Figure 2. LMX2615EVM Setup and Description
1. Power:
a. Set power supply to 3.3 V with 600-mA current limit and connect to VCC SMA.
2. Input Signal
a. The EVM is designed for a 100-MHz input reference that should be connected to the OSCin SMA.
Some of the options for this could be a signal generator, the 100 MHz output from the Reference
Pro board, or a very clean signal source such as the Wenzel 501-4623G ultra-low phase noise 100
MHz reference
3. Programming Interface:
• Reference Pro will provide SPI interface to program LMX2615. If using this, Connect USB cable
from laptop or PC to USB port in Reference Pro. This provides power to Reference Pro Board and
communication with TICS GUI
• The other option is to use the dip switch on the board to use Pin mode.
4. Output:
1. Connect RFoutAP to a phase noise analyzer and connect a 50-Ωterminator to RFoutAM.

www.ti.com Setting Up the Software
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LMX2615EVM-CVAL Wideband 15-GHz Synthesizer
2 Setting Up the Software
1. Download the TICS Pro from the TI Website at www.ti.com/tool/TICSPRO-SW and install.
2. From the menu bar choose Select Device →PLL + VCO →LMX2615
Figure 3. Search for LMX2615 on TICS Pro
3. Verify the communication setup with Reference Pro. To do this, select USB communications →
Interface . Click on the identify button and the LED on the Reference Pro should blink.

Bringing LMX2615 to a Lock State www.ti.com
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LMX2615EVM-CVAL Wideband 15-GHz Synthesizer
3 Bringing LMX2615 to a Lock State
Load the default mode as shown in Figure 4 The PLL GUI tab gives useful feedback to the user that is
helpful in getting the best performance out of the device
• Items highlighted in orange or red indicate that something may be sub-optimal. To view the comment,
simply mouse over the colored item and a tooltip will appear. In this case, the feedback suggests that
CAL_CLK_DIV and VCO_SEL can be adjusted to improve the VCO calibration time, SEG1_EN could
be disabled for better spurs and lower current, and that FCAL_EN should be toggled to calibrate the
VCO.
• Mouse over any item and it will display the field value in the lower left corner including the field name,
register location, and description.
• On the bottom is the status bar, which indicates when registers are written to and the status of the
USB2ANY/Reference Pro board. In this case, it is indicating that there is no board connected.
Figure 4. TICS Pro GUI LMX2615 Default Configuration
The GUI gives useful feedback to the user to help understand how to program and get the best
performance out of the de

www.ti.com Current Loop Filter Configuration
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LMX2615EVM-CVAL Wideband 15-GHz Synthesizer
4 Current Loop Filter Configuration
Note that if the phase detector frequency is changed significantly, the loop filter needs to be redesigned.
Table 1. Current Loop Filter Configuration
PARAMETER VALUE
VCO Gain 132 MHz/V
Loop Bandwidth 285 kHz
Phase Margin 65 deg
C1_LF 390 pF
C2_LF 68 nF
C3_LF Open
C4_LF 1800 pF
R2 68 Ω
R3_LF 0 Ω
R4_LF 18 Ω
Effective Charge Pump Gain 15 mA
Phase Detector Frequency (MHz) 200 MHz
VCO Frequency Designed for 15 GHz, but works
over the whole frequency range
Figure 5. Current Loop Filter Configuration
For detailed design and simulation, see the PLLatinum Sim Tool.
For application notes, videos, and other technical information on TI products, see http://www.ti.com/pll.

Typical Phase Noise www.ti.com
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LMX2615EVM-CVAL Wideband 15-GHz Synthesizer
5 Typical Phase Noise
Figure 6. Typical Phase Noise with Wenzel 100 MHz Input
Figure 7. PLLatinum Sim Simulation Result for Phase Noise with Wenzel 100 MHz Input
(Total Trace = Simulation, Comparison Trace = Actual Measurement)

www.ti.com Typical Phase Noise
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LMX2615EVM-CVAL Wideband 15-GHz Synthesizer
Figure 8. Typical Phase Noise 100 MHz Reference Pro as Input
Figure 9. PLLatinum Sim Simulation using 100 MHz Reference Pro as Input
(Total Trace = Simulation, Comparison Trace = Actual Measurement)

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Schematic
Appendix A
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Schematic
Figure 10. Schematic