Texas Instruments LMX2820EVM User manual

User’s Guide
LMX2820EVM Evaluation Module
Noel Fung
ABSTRACT
The LMX2820EVM is designed to evaluate the performance of LMX2820. This board consists of a LMX2820
device.
The LMX2820 is a high-performance wideband synthesizer that can generate any frequency from 44.14 MHz to
22.6 GHz. The device runs from a single 3.3-V supply and has integrated LDOs that eliminate the need for
onboard low noise LDOs.
Table of Contents
1 Trademarks..............................................................................................................................................................................2
2 LMX2820EVM Evaluation Module..........................................................................................................................................3
2.1 Evaluation Module Contents.............................................................................................................................................. 3
2.2 Evaluation Setup Requirement.......................................................................................................................................... 3
2.3 Resources.......................................................................................................................................................................... 3
www.ti.com Table of Contents
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3 Setup........................................................................................................................................................................................4
3.1 Connection Diagram.......................................................................................................................................................... 4
3.2 Power Supply..................................................................................................................................................................... 4
3.3 Reference Clock.................................................................................................................................................................4
3.4 RF Output...........................................................................................................................................................................4
3.5 Programming......................................................................................................................................................................4
3.6 Evaluation Software........................................................................................................................................................... 5
4 Typical Measurement..............................................................................................................................................................6
4.1 Default Configuration......................................................................................................................................................... 6
4.2 Additional Tests.................................................................................................................................................................. 8
5 Schematic..............................................................................................................................................................................10
6 PCB Layout and Layer Stack-Up.........................................................................................................................................12
6.1 PCB Layer Stack-Up........................................................................................................................................................ 12
6.2 PCB Layout...................................................................................................................................................................... 12
7 Bill of Materials..................................................................................................................................................................... 15
8 Troubleshooting Guide.........................................................................................................................................................16
A Using Different Reference Clock........................................................................................................................................ 17
B USB2ANY Firmware Upgrade..............................................................................................................................................18
C Revision History...................................................................................................................................................................20
List of Figures
Figure 3-1. EVM Connection Diagram.........................................................................................................................................4
Figure 3-2. Select Device in TICS Pro.........................................................................................................................................5
Figure 3-3. Default Mode............................................................................................................................................................. 5
Figure 4-1. Loop Filter................................................................................................................................................................. 6
Figure 4-2. Default Output........................................................................................................................................................... 7
Figure 4-3. SYSREF Pulsed Mode Setting..................................................................................................................................8
Figure 4-4. Offset Mixing With PFDIN Pin Setting....................................................................................................................... 8
Figure 4-5. External VCO Mode Setting...................................................................................................................................... 9
Figure 4-6. Register Readback....................................................................................................................................................9
Figure 5-1. LMX2820EVM Schematic (Page 1).........................................................................................................................10
Figure 5-2. LMX2820EVM Schematic (Page 2).........................................................................................................................11
Figure 6-1. PCB Layer Stack-Up............................................................................................................................................... 12
Figure 6-2. Top Layer.................................................................................................................................................................12
Figure 6-3. RF GND Layer.........................................................................................................................................................13
Figure 6-4. Signal GND Layer................................................................................................................................................... 13
Figure 6-5. Bottom Layer........................................................................................................................................................... 14
Figure 8-1. Troubleshooting Guide............................................................................................................................................ 16
Figure B-1. Firmware Requirement........................................................................................................................................... 18
Figure B-2. Firmware Loader.....................................................................................................................................................18
Figure B-3. BSL Button..............................................................................................................................................................18
Figure B-4. Update Firmware.................................................................................................................................................... 19
Figure B-5. Firmware Update Complete.................................................................................................................................... 19
Figure B-6. USB Communications.............................................................................................................................................20
List of Tables
Table 4-1. Loop Filter Configuration.............................................................................................................................................6
Table 7-1. Bill of Materials..........................................................................................................................................................15
Table A-1. Reference Clock Input Configuration........................................................................................................................17
1 Trademarks
PLLatinum™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
Trademarks www.ti.com
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2 LMX2820EVM Evaluation Module
2.1 Evaluation Module Contents
In the box, there is:
• One LMX2820EVM board (HSDC060-001)
• One USB2ANY (HPA665)
• One USB cable
• One 10-pin ribbon cable
2.2 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 (optional)
• A high quality signal generator (optional)
• Texas Instruments Clocks and Synthesizers TICS Pro software
• Texas Instruments PLLatinum™ Simulator Tool (optional)
2.3 Resources
Related evaluation and development resources are as follows:
•TICS Pro software
•PLLatinum Simulator Tool (PLL Sim)
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3 Setup
3.1 Connection Diagram
HPA665
USB2ANY
Texas Instruments
50 
Figure 3-1. EVM Connection Diagram
3.2 Power Supply
Apply 3.3 V to the J8 header. The acceptable supply voltage range is 3.2 V to 3.4 V.
3.3 Reference Clock
Connect the OSCINP SMA connector to a high-quality, 100-MHz signal source. The OSCINN SMA connector
can be left open because the OSCIN_N pin is terminated onboard.
The EVM is configured for single-ended input with the OSCIN_P pin connected to the OSCINP SMA connector
and the OSCIN_N pin 50-Ω terminated onboard. If required, the EVM can be modified to operate with a different
clock source in a different configuration. See Appendix A for more details.
3.4 RF Output
Connect either the RFOUTAP or RFOUTAN SMA connector to a signal analyzer. The unused connector must be
terminated with a 50-Ω resistor or SMA load. Output frequency is 6 GHz and the amplitude is about +3 dBm.
By default, the TICS Pro evaluation software has RFOUTB power down. These SMA connectors can be left
open.
3.5 Programming
Connect the ribbon cable from the USB2ANY to the LMX2820EVM.
Connect the USB cable from a PC to USB port in the USB2ANY. This provides power supply to the USB2ANY
and communication with the TICS Pro. A firmware update may be required. See Appendix B for more details.
Setup www.ti.com
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3.6 Evaluation Software
Download and install TICS Pro to a PC.
Run the software and follow these steps to start the program.
1. Go to Select Device → PLL + VCO → LMX2820.
Figure 3-2. Select Device in TICS Pro
2. The "ReadMe" page will load. Please take a minute to read the content to have a basic understanding of the
GUI.
3. Go to Default Configuration → EVM Default Mode.
Figure 3-3. Default Mode
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4 Typical Measurement
4.1 Default Configuration
4.1.1 Loop Filter
The parameters for the loop filter are listed in Table 4-1.
Table 4-1. Loop Filter Configuration
PARAMETER VALUE
C1_LF 470 pF
C2_LF 68 nF
C3_LF 2.2 nF
R2_LF 68.1 Ω
R3_LF 18.2 Ω
Figure 4-1. Loop Filter
Typical Measurement www.ti.com
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4.1.2 Typical Output
1. Follow Section 3 to set up the evaluation.
2. Click Write All Registers to write all the registers to LMX2820.
The default output is 6 GHz.
Figure 4-2. Default Output
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4.2 Additional Tests
4.2.1 SYSREF Example
The SROUT of LMX2820 can be used to generate or duplicate SYSREF signal. The output of SROUT can be a
single pulse, series of pulse, or a continuous stream of pulses. These pulses are synchronous with the RFOUT
signal with an adjustable delay. To use the SYSREF capability, the PLL must be in phase SYNC mode with
PHASE_SYNC_EN = 1. Here is an example of Pulsed mode.
Figure 4-3. SYSREF Pulsed Mode Setting
4.2.2 Offset Mixing With PFDIN Pin
The LMX2820 supports offset mxing with PFDIN pin. In this mode, the internal N divider is bypassed.
When using offset mixing with PFDIN pin, the phase detector must operate with a single PFD. As a result, the
charge pump current is equal to half the current setting made in register CPG.
Figure 4-4. Offset Mixing With PFDIN Pin Setting
Typical Measurement www.ti.com
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4.2.3 External VCO Mode
In addition to the internal VCO, LMX2820 also support working with an external VCO. The polarity of the phase
detector has to be set properly to match with the actual Vtune characteristic. The LMX2820EVM offers various
options to implement passive or active loop filter onboard.
Figure 4-5. External VCO Mode Setting
4.2.4 Register Readback
To read back the written register values, follow these steps:
1. Click the Register Name that you want to read back.
2. Click Read Register to read back the register value.
Figure 4-6. Register Readback
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5 Schematic
Figure 5-1. LMX2820EVM Schematic (Page 1)
Schematic www.ti.com
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