Texas Instruments LMX248 Series User Manual
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Texas Instruments LMX248 Series User Manual

Texas Instruments LMX248 Series User Manual

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LMX248x Evaluation Board
User's Guide
Revised – March 2014
SNAU137

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Summary of Contents for Texas Instruments LMX248 Series

  • Page 1 LMX248x Evaluation Board User's Guide Revised – March 2014 SNAU137...
  • Page 2 LMX248x Evaluation Board Operating Instructions SNAU137 LMX248x Evaluation Board User’s Guide Revised - March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 3: Table Of Contents

    ..............................28 PPENDIX UILD IAGRAMS C: B ..............................31 PPENDIX ILL OF ATERIALS D: Q EVM C ......................34 PPENDIX UICK TART FOR OMMUNICATIONS Revised - March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 4: Equipment

    The oscilloscope and probes should be capable of measuring the output frequencies of interest when evaluating this board. The Agilent Infiniium DSO81204A was used in creating these evaluation board instructions. SNAU137 LMX248x Evaluation Board User’s Guide Revised - March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 5: Basic Operation

    Connect PC to the uWire header. 4. Start CodeLoader4.exe. 5. Click “Select Device”  “PLL-Fractional”  LMX248x depending on which chip is on your board. Revised - March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...
  • Page 6 6. Select USB or LPT Communication Mode on the Port Setup tab as appropriate. 7. Click “CTRL + L” to load settings into device SNAU137 LMX248x Evaluation Board User’s Guide Revised - March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 7: Lmx2485 Board Information

    820 Ω PLL Supply 2.5 Volts VCO Supply 3 Volts Other Information VCO Used VARIL2450U VCO Gain 55 MHz/Volt VCO Input 22 pF Capacitance Revised - March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...
  • Page 8 PLL Supply 2.5 Volts 8.2 KΩ VCO Supply 3 Volts Other Information VCO Used VARIL191-773U VCO Gain 18 MHz/Volt VCO Input 100 pF Capacitance SNAU137 LMX248x Evaluation Board User’s Guide Revised - March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 9: Rf Pll Phase Noise

    VCO phase noise could still be degrading the in-band phase noise. Revised - March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...
  • Page 10 1600 uA current was that it makes the loop filter capacitors 8X larger and also, the lower current allows one to experiment with lower comparison frequencies like 2.5 MHz, 5 MHz, and 10 MHz. SNAU137 LMX248x Evaluation Board User’s Guide Revised - March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 11: Rf Pll Fractional Spurs

    At 2480.2 MHz output frequency, the primary fractional spur at 200 kHz is -80.8 dBc, and the sub-fractional spur at 100 kHz is -73.4 dBc. Revised - March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 12: Rf Pll Lock Time

    1110 uS. Peak time without cycle slip reduction is 1622 uS. Positive lock time is 1220 uS Negative Lock time is 1711 uS SNAU137 LMX248x Evaluation Board User’s Guide Revised - March 2014 Copyright © 2014, Texas Instruments Incorporated...
  • Page 13 222 uS. Peak time with cycle slip reduction is 222 uS. Positive lock time is 345 uS Negative Lock time is 378 uS Revised - March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 14: If Pll Lock Time

    IF PLL Lock Time Peak time is 97.8 uS Peak Time is 133.3 uS Positive Lock time is 510 uS Negative Lock Time is 474 uS SNAU137 LMX248x Evaluation Board User’s Guide Revised - March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 15: If Pll Phase Noise

    IF PLL Phase Noise Revised - March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 16: If Pll Spurs

    Spurs at 50 kHz offset for an output frequency of 770 MHz are -81.7 dBc. Spurs at 50 kHz offset for an output frequency of 780 MHz are -71.7 dBc. SNAU137 LMX248x Evaluation Board User’s Guide Revised - March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 17: Lmx2486 Board Information

    Output 2100 - 2200 4.7 nF Frequency Open 680 pF 3.3 Volts from 4.7 KΩ PLL Supply regulator VCO Supply 5.5 volts VCO Information Revised – March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 18: Rf Pll Phase Noise

    Loop Bandwidth is about 10 kHz. Note that the phase noise gradually improves as one goes farther from the carrier. This was taken with the IF PLL powered up and IF VCO connected. SNAU137 LMX248x Evaluation Board User’s Guide Revised – March 2014 Copyright © 2014, Texas Instruments Incorporated...
  • Page 19 For this plot, the charge pump was increased to 16X and the other conditions were the same. Revised – March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 20: Rf Pll Fractional Spurs

    At 3200.2 MHz output frequency, the primary fractional spur at 200 kHz is –82 dBc and the sub-fractional spur is below the noise. SNAU137 LMX248x Evaluation Board User’s Guide Revised – March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 21: Rf Pll Lock Time (With A Specturm Analyzer)

    So cycle slip reduction is very worthwhile, considering it uses no external components and requires additional software overhead, once the part is set up. Revised – March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 22: If Pll Phase Noise

    Above is the IF PLL phase noise with the RF PLL powered up. The above plot was taken with the RF PLL powered down and IF VCO disconnected. SNAU137 LMX248x Evaluation Board User’s Guide Revised – March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 23: If Pll Spurs

    Fout = 2200 MHz Spurs at 200 kHz are not there and actually reducing the noise due to discrete sampling effects. Revised – March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 24: If Pll Lock Time

    PLL overshoots. Peak Time is 37.8 uS Positive Lock time is 253 uS Negative Lock Time is 249 uS SNAU137 LMX248x Evaluation Board User’s Guide Revised – March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 25: Lmx2487 Board Information

    0.5 – 4.5 Universal Microwave UMT-1050-I12 6800 - 6800 0 - 20 Spectrum Microwave HVA103SM-22 6800 - 8000 1 -13 Hittite HMC532LP4 7100 - 7900 Revised – March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 26: Replacing The Vco With A Footprint Compatible Vco

    Zcomm. However, it is suggested that if an LMX2487 board is being modified, the setup for that should be verified. The dot signifies the tuning voltage. SNAU137 LMX248x Evaluation Board User’s Guide Revised – March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 27: Appendix A: Schematics

    Appendix A: Schematics LMX2487 Revised – March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 28: Appendix B: Build Diagrams

    Appendix B: Build Diagrams LMX2485 SNAU137 LMX248x Evaluation Board User’s Guide Revised – March 2014 Copyright © 2014, Texas Instruments Incorporated...
  • Page 29 LMX2486 Revised – March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...
  • Page 30 LMX2487 SNAU137 LMX248x Evaluation Board User’s Guide Revised – March 2014 Copyright © 2014, Texas Instruments Incorporated...

  • Page 31: Appendix C: Bill Of Materials

    R12, R14, R16, R18, R20, R22 Steward LI0603D301R-00 Inductor Ferrite L1, L2 Texas Instruments LMX2485 Silicon 2400 - VARIL VCO191-2450U 2480 VARIL VCO191-773U 760-780 Revised – March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...
  • Page 32 Cermaic R13, R15, R17, R19, R23 Texas Instruments LMX2486SQ 3.6 V Silicon VARIL VCO690-3300T 3120-3300 VARIL VCO190-2200T 2100-2200 Texas Instruments LP3985IM5X-3.3 SOT23 3.3V Silicon SNAU137 LMX248x Evaluation Board User’s Guide Revised – March 2014 Copyright © 2014, Texas Instruments Incorporated...
  • Page 33 R13, R15, R17, R19, R21, R23 Vishay CRCW0603123JRT1 Kohm 0603 10 V Cermaic R12, R14, R16, R18, R20, R22 Steward LI0603D301R-00 Inductor Ferrite L1, L2 VARIL VARIL VCO191-773U 760-780 Revised – March 2014 LMX248x Evaluation Board User’s Guide SNAU137 Copyright © 2014, Texas Instruments Incorporated...

  • Page 34: Appendix D: Quick Start For Evm Communications

    There are two options in communicating with the uWire interface from the computer. OPTION 1 Open Codeloader.exe  Click “Select Device”  Click “Port Setup” tab  Click “LPT” (in Communication Mode) OPTION 2 SNAU137 LMX248x Evaluation Board Instructions Revised – March 2014 Copyright © 2014, Texas Instruments Incorporated...
  • Page 35 Open Codeloader.exe  Click “Select Device”  Click “Port Setup” Tab  Click “USB” (in Communication Mode) *Remember to also make modifications in “Pin Configuration” Section according to Table above Revised – March 2014 LMX248x Evaluation Board Instructions SNAU137 Copyright © 2014, Texas Instruments Incorporated...
  • Page 36 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue.
  • Page 37 Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Texas Instruments LMX2487E-EVM LMX2485E-EVAL/NOPB...

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