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LMX2595EVM: LMX2595EVM

manoj chugh
Prodigy 20 points
Part Number: LMX2595EVM
Other Parts Discussed in Thread: LMX2595

Tool/software:

I am using LMX2595 evaluation board along with USB to serial board using tics pro software board to generate the frequency  from 8.0 to 15.5GHz range.

Spur performance up to 15 GHz is fine. Above 15GHz side band spur level are lifting up. Moreover when i am tuning for 1MHz step from 15.001to 15.5 GHz phase noise and spur performance is getting degrade.

Plot for different frequencies are enclosed herewith .Please suggest how to improve the performance in the mentioned range and what steps to be followed while tuning for 1MHz step .

Thanks in advance.

8.5 GHz15.03GHz15.01 GHz15.02GHz

  • 0
    TI__Genius 15561 points

    Hi Manoj,

    Can you share your configuration (.tcs) file ?

    Regards,

    Vicente

  • 0 in reply to vicente flores prado
    TI__Genius 15561 points

    I went on bench and tried ramping by 1MHz using a 15GHz direct VCO frequency and I do see a spur at at offset equal to my ramp step 

    So for example if I ramped twice we expect to be at 15.002MHz and I would see a spur at 2MHz - seeing spurs in ramping mode is expected. 

    Spurs will not be avoidable in ramping mode. You can reduce the spur amplitudes by reducing the charge pump current but you will not be able to eliminate them. 

    Regards, 

    Vicente 

  • 0 in reply to vicente flores prado
    Prodigy 20 points

    Hi Vicente

    Thanks for the prompt response. I have reduced the charge pump current from 15 mA to 3mA and PFD delay from 4 to 2 . I am tuning in discrete step not in ramp mode. I have seen reduction in the spur level for 10MHz step but when I am tuning for 1MHz step as you mentioned level is reduced but it is not eliminated.

    15001MHz.txt 
    R112	0x700000
R111	0x6F0000
R110	0x6E0000
R109	0x6D0000
R108	0x6C0000
R107	0x6B0000
R106	0x6A0000
R105	0x690021
R104	0x680000
R103	0x670000
R102	0x660000
R101	0x650011
R100	0x640000
R99	0x630000
R98	0x620000
R97	0x610888
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	0x4E0003
R77	0x4D0000
R76	0x4C000C
R75	0x4B0800
R74	0x4A0000
R73	0x49003F
R72	0x480001
R71	0x470081
R70	0x46C350
R69	0x450000
R68	0x4403E8
R67	0x430000
R66	0x4201F4
R65	0x410000
R64	0x401388
R63	0x3F0000
R62	0x3E0322
R61	0x3D00A8
R60	0x3C0000
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	0x2E07FC
R45	0x2DD0DF
R44	0x2C1FA3
R43	0x2BD70A
R42	0x2A80A3
R41	0x290000
R40	0x280000
R39	0x27FFFF
R38	0x26FFFF
R37	0x250204
R36	0x240025
R35	0x230004
R34	0x220000
R33	0x211E21
R32	0x200393
R31	0x1F43EC
R30	0x1E318C
R29	0x1D318C
R28	0x1C0488
R27	0x1B0003
R26	0x1A0DB0
R25	0x190624
R24	0x18071A
R23	0x17007C
R22	0x160001
R21	0x150401
R20	0x14E048
R19	0x1327B7
R18	0x120064
R17	0x11012C
R16	0x100080
R15	0x0F064F
R14	0x0E1E40
R13	0x0D4000
R12	0x0C5001
R11	0x0B0018
R10	0x0A10D8
R9	0x091604
R8	0x082000
R7	0x0740B2
R6	0x06C802
R5	0x0500C8
R4	0x040A43
R3	0x030642
R2	0x020500
R1	0x010808
R0	0x00251C
    15002MHz.txt 
    R112	0x700000
R111	0x6F0000
R110	0x6E0000
R109	0x6D0000
R108	0x6C0000
R107	0x6B0000
R106	0x6A0000
R105	0x690021
R104	0x680000
R103	0x670000
R102	0x660000
R101	0x650011
R100	0x640000
R99	0x630000
R98	0x620000
R97	0x610888
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	0x4E0003
R77	0x4D0000
R76	0x4C000C
R75	0x4B0800
R74	0x4A0000
R73	0x49003F
R72	0x480001
R71	0x470081
R70	0x46C350
R69	0x450000
R68	0x4403E8
R67	0x430000
R66	0x4201F4
R65	0x410000
R64	0x401388
R63	0x3F0000
R62	0x3E0322
R61	0x3D00A8
R60	0x3C0000
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	0x2E07FC
R45	0x2DD0DF
R44	0x2C1FA3
R43	0x2BAE14
R42	0x2A8147
R41	0x290000
R40	0x280000
R39	0x27FFFF
R38	0x26FFFF
R37	0x250204
R36	0x240025
R35	0x230004
R34	0x220000
R33	0x211E21
R32	0x200393
R31	0x1F43EC
R30	0x1E318C
R29	0x1D318C
R28	0x1C0488
R27	0x1B0003
R26	0x1A0DB0
R25	0x190624
R24	0x18071A
R23	0x17007C
R22	0x160001
R21	0x150401
R20	0x14E048
R19	0x1327B7
R18	0x120064
R17	0x11012C
R16	0x100080
R15	0x0F064F
R14	0x0E1E40
R13	0x0D4000
R12	0x0C5001
R11	0x0B0018
R10	0x0A10D8
R9	0x091604
R8	0x082000
R7	0x0740B2
R6	0x06C802
R5	0x0500C8
R4	0x040A43
R3	0x030642
R2	0x020500
R1	0x010808
R0	0x00251C
    15001MHz15002MHz. Configuration files text file and snapshot are attached for reference. Please suggest any parameter for improvement in the spurs

  • 0 in reply to manoj chugh
    TI__Genius 15561 points

    Hi Manoj, 
    As mentioned previously - you will always see spurs in ramp mode it is unavoidable. 
    You can reduce the charge current as you've done to reduce the spur amplitude but that's about it - you will not be able to eliminate the spurs all together. 

    Regards, 

    Vicente