LMX2582: RF output Response contains lot of Harmonics

shivakant dwivedi

Part Number: LMX2582

Hi,

I am using LMX2582 for generating RF output from 950MHz to 1450MHz.

But we are getting lot of harmonics which are not suppressed as per mentioned in datasheet ie -27dBc for 2nd harmonics & -25dBc for 3rd Harmonic.

I have attached the schematic & test results for 1.2GHz.Please verify it.

I have terninated channel A & Taking output from Channel B only by converting differential out put of LMX2582 to single ended with the help of Balun TCM1-43X.

Test result @ for 1.2 GHz output:

TICS pro settings:

over 6 years ago

0 Hao Z over 6 years ago

TI__Mastermind 18070 points

Hi Shivakant,

Have you tried evaluating TI EVM and did you see similar behavior?

Regards,
Hao

0 shivakant dwivedi over 6 years ago in reply to Hao Z

Intellectual 960 points

Hi Hao,

No,I did not try with TI EVM as i have not EVM.

Can you check it from your side with TI EVM?

Why i am getting so high level Harmonics.

0 Hao Z over 6 years ago in reply to shivakant dwivedi

TI__Mastermind 18070 points

Hi Shivakant,

The default setup was configured for best jitter so the first divider is set to 3. If you want lower second harmonic, please set it to 2.

Third harmonic is needed for square wave so that shouldn't be of any concern.

Regards,

Hao

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LMX2582: RF output Response contains lot of Harmonics