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LMX2594: LMX2594 Phase hit issues

Nagamine Shinji
Prodigy 10 points

Part Number: LMX2594

Hi team,

Have you ever had phase hit issues with the LMX2594 ?
Do you have any suggestions why I might be experiencing phase hit problems with the LMX2594 ?
Can you suggest any help?

Best regards.
Shinji Nagamine

  • 0
    TI__Guru** 121600 points

    Hi Shinji-san,

    Could you be more specific what phase hit issue you are experiencing? A description of your operation procedure and some test plots will be helpful for us to understand your problem. 

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Hi Noel,

    I'm using LMX2594 for local oscillator on our wireless equipment.
    Now, I'm investigating about bit error which is occurred during temperature changes from +10ºC to -10ºC.

    bit error is occurred while lowering the temperature.
    bit error isn't occurred while rising the temperature.
    bit error isn't occurred at constant temperture.

    This phenomenon is also occurred on the mesurement of the atttached blockdiagram.


    So,I think that phase-hits of LMX2594 might be one of the causes.

    Please tell me whether LMX2594 might occur phase-hits.
    I would like any suggestions to prevent phase-hits or to reduce phase-hits.

    Setting for our board is below.
    The output frequency is 10408MHz.
    The phase detector frequency is 100MHz.
    The register configuration is attached.

    Fullscreen LMX2594_resister.txt Download 
    R112  0x700000
R111  0x6F0000
R110  0x6E0000
R109  0x6D0000
R108  0x6C0000
R107  0x6B0000
R106  0x6A0007
R105  0x690000
R104  0x680000
R103  0x670000
R102  0x660000
R101  0x650000
R100  0x640000
R99  0x630000
R98  0x620000
R97  0x610800
R96  0x600000
R95  0x5F0000
R94  0x5E0000
R93  0x5D0000
R92  0x5C0000
R91  0x5B0000
R90  0x5A0000
R89  0x590000
R88  0x580000
R87  0x570000
R86  0x560000
R85  0x550000
R84  0x540000
R83  0x530000
R82  0x520000
R81  0x510000
R80  0x500000
R79  0x4F0000
R78  0x4E016F
R77  0x4D0000
R76  0x4C000C
R75  0x4B0800
R74  0x4A0000
R73  0x49003F
R72  0x480000
R71  0x470081
R70  0x46C350
R69  0x450000
R68  0x4403E8
R67  0x430000
R66  0x4201F4
R65  0x410000
R64  0x401388
R63  0x3F0000
R62  0x3E0322
R61  0x3D00A8
R60  0x3C03E8
R59  0x3B0001
R58  0x3A8001
R57  0x390020
R56  0x380000
R55  0x370000
R54  0x360000
R53  0x350000
R52  0x340820
R51  0x330080
R50  0x320000
R49  0x314180
R48  0x300300
R47  0x2F0300
R46  0x2E07FD
R45  0x2DC8C0
R44  0x2C3FA3
R43  0x2B0008
R42  0x2A0000
R41  0x29000C
R40  0x280000
R39  0x270064
R38  0x260000
R37  0x258404
R36  0x240068
R35  0x230004
R34  0x220000
R33  0x211E21
R32  0x200393
R31  0x1F03EC
R30  0x1E318C
R29  0x1D318C
R28  0x1C0488
R27  0x1B0002
R26  0x1A0DB0
R25  0x190C2B
R24  0x18071A
R23  0x17007C
R22  0x160001
R21  0x150401
R20  0x14F848
R19  0x1327B7
R18  0x120064
R17  0x11012C
R16  0x100080
R15  0x0F064F
R14  0x0E1E70
R13  0x0D4000
R12  0x0C5001
R11  0x0B0018
R10  0x0A10D8
R9  0x091604
R8  0x082000
R7  0x0740B2
R6  0x06C802
R5  0x0500C8
R4  0x041943
R3  0x030642
R2  0x020500
R1  0x01080B
R0  0x002414

    Our schematic and board layout is confidential information.
    So, I would like to send it by email or something private messenger.

    Best regards.
    Shinji Nagamine

  • 0 in reply to Nagamine Shinji
    TI__Guru** 121600 points

    Hi Nagamine-san,

    Did you check the output of LMX2954 while the temperature change? 

    Regarding the configuration, couples of change are recommended.

    Since your fpd is 200MHz, FCAL_HPFD_ADJ should be 0x2. Your reference clock is 100MHz, CAL_CLK_DIV should be 0x0. We can put ACAL_CMP_DLY below 25, that would reduce the calibration speed. 

    You are not using any vco calibration assist, we suggest make VCO_SEL (Start VCO7) = 0x4 and VCO_CAPCTRL_STRT (Start Capcode) = 0x1.