User's Guide
SNAU219–June 2017
LMX2595 EVM Instructions – 19-GHz Wideband Low Noise
PLL With Integrated VCO
This Evaluation Module is for the LMX2595, which is the first PLL with integrated VCO in industry to get
fundamental VCO output up to 15 GHz. The industry leading PLL FOM is -236 dBc/Hz with 1/f of -129
dBc/Hz. This device supports JESD204B standard (it can generate or repeat the SYSREF signal) which
makes it ideal to clock high speed data converters. The integrated jitter from the EVM measurements is
less than 50 fs at 9 GHz carrier frequency. By providing a SYNC signal, the user can synchronize the
output phase across multiple LMX2595 devices. LMX2595 can also generate a frequency ramp which can
be demonstrated in this evaluation module. With an on-board oscillator, setup process only requires a
3.3V power supply and an included Reference Pro module (For SPI Programming interface). The software
is simple, with an intuitive and user friendly GUI.
1 Evaluation Board Setup .................................................................................................... 3
2 EVM Description ............................................................................................................. 4
3 Bringing LMX2595 to a Lock State ........................................................................................ 8
4 Current Loop Filter Configuration ........................................................................................ 10
5 Key Results to Expect ..................................................................................................... 11
Appendix A Schematic .......................................................................................................... 12
Appendix B Bill of Materials .................................................................................................... 13
Appendix C Board Layers Stack-Up........................................................................................... 15
Appendix D Changing Reference Oscillator and Setup..................................................................... 16
Appendix E Connecting Reference Pro....................................................................................... 18
Appendix F Ramping Feature ................................................................................................. 21
Appendix G SYSREF Feature ................................................................................................. 23
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Figure 1. LMX2595EVM
Contents
LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
Copyright © 2017, Texas Instruments Incorporated
Integrated VCO
1
Appendix H VCO Calibration ................................................................................................... 28
Appendix I Enabling Onboard DC-DC Buck Converter (TPS62150)..................................................... 30
Appendix J Appendix J: Using the VCO Doubler ........................................................................... 31
Trademarks
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LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
Integrated VCO
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3.3 Volt supply
LMX2594
Output to
analyzer
Serial Interface
Reference
Pro
LMX2595EVM
USB Æ PC
Reference XO
If unused,
terminate
(50ohm)
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1 Evaluation Board Setup
Evaluation Board Setup
Figure 2. LMX2595EVM Setup
SPACER
1. Power:
(a) Set power supply to 3.3 V with 600-mA current limit and connect to VCCSMA.
2. Input Signal:
(a) VC-708 100-MHz on-board oscillator enabled (default). To use another reference, see Appendix D.
3. Programming Interface:
• Reference Pro will provide SPI interface to program LMX2595:
(a) 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
(b) Connect 10 pin ribbon cable from Reference Pro to LMX2595EVM as shown above.
4. Output:
(a) Connect RFoutAM or RFoutAP to a phase noise Analyzer. Connect a 50-Ω on the unused output if
you are using only single-ended. Use a balun if you are using differential.
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LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
Integrated VCO
3
Power supply.
3.3 Volt
Voltage regulator
not enabled
Diff. RF output A
Diff. RF output B
100 MHz XO
Diff. reference input
Single ended signal
can be used.
Lock indicator LED
Switch to select:
1) SPI Read back
2) Lock indicator
(1 OR 2)
LMX2595
Serial interface
Loop filter components
(*_LF)
123456789
10
Serial interface pin out
Sync
SysRef
EVM Description
2 EVM Description
The LMX2595 is populated on a 4-layer PCB. This brief description should help you use the EVM:
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The serial interface pin description is as follow:
4
LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
Integrated VCO
Table 1. EVM and Serial Interface Connector
Figure 3. LMX2595EVM Description
Description
NO. NAME
1
2 CSB
3 MUXout
4 SDI
5 Not Used
6 GND
7 RampCLK
8 SCK
9 SysRefReq
10 SYNC
RAMPDIR and CE (Choose with
Resistors on Board)
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The LD switch must be on to enable Lock indicator:
EVM Description
Figure 4. LD Lock Detect
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LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
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Integrated VCO
5
EVM Description
2.1 Installing the Software
1. Download TICS Pro from the TI Website at www.ti.com/tool/TICSPRO-SW
2. Install it by following the wizard
3. Search for LMX2595: Click on Select Device From menu bar →PLL+VCO→LMX2595
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Figure 5. Search for LMX2595 on TICS Pro
4. You are now ready to use this software. Verify that you can communicate with Reference Pro. Select
interface under USB communications:
Figure 6. USB Communications on TICS Pro
6
LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
Integrated VCO
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5. Click on identify and you will see the LED (MSP430 Supplied) Blink on Reference Pro
EVM Description
Figure 7. USB Communication Between TICS Pro and Reference Pro
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LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
Copyright © 2017, Texas Instruments Incorporated
Integrated VCO
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Bringing LMX2595 to a Lock State
3 Bringing LMX2595 to a Lock State
Load the default mode by selecting it as shown in Figure 8:
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Figure 8. TICS Pro GUI LMX2595 Default Configuration
8
LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
Integrated VCO
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For best results, in the User Controls Tab in TICS Pro. Under General Controls, check and uncheck the
Reset box. After the reset, Write all registers as shown in Figure 9:
Bringing LMX2595 to a Lock State
Figure 9. TICS Pro Write All Registers
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LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
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Integrated VCO
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Current Loop Filter Configuration
4 Current Loop Filter Configuration
The parameters for the loop filters are:
Table 2. 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
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Designed for 15 GHz, but works
over the whole frequency range
10
Figure 10. Current Loop Filter Configuration
For detailed design and simulation, see the PLLatinum Sim Tool.
For application notes, blogs,or videos on our products, see http://www.ti.com/pll.
LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
Integrated VCO
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5 Key Results to Expect
Key Results to Expect
This assumes that the input reference is very clean, such as a 100-MHz Wenzel oscillator. A signal
generator is NOT sufficiently clean. The LMX2595 requires an external reference.
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Figure 11. Phase Noise Plot at 14-GHz Output Frequency
LMX2595 EVM Instructions – 19-GHz Wideband Low Noise PLL With
Copyright © 2017, Texas Instruments Incorporated
Integrated VCO
11
Appendix A
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Schematic
12
Schematic
Figure 12. Schematic
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