LMX8410L: NO IF output when using external LO

ken mason

Prodigy 160 points

Part Number: LMX8410L

We are using the LMX8410 with an external LO at 9.8GHz, inputting a signal at 9.4GHz.

There is no IF output signal at 400MHz, just the DC offset.

We have checked all the register settings and they seem to match the datasheet.

If possible could you send us a register file for the external LO configuration just in case we missed something.

Also we have the circuit elements on the board for the internal PLL. However table 5 states that some lines should be configured differently, if not configured as per the table could that give the error above (no IF)?

regards

Ken

10 months ago

0 vicente flores prado 10 months ago

TI__Mastermind 20821 points

Hi Ken,
Table 5 refers to the requirements for each pin when using external LO mode. For example, pins 5/8/9 must be grounded in external LO mode.

Please try this configuration. I don't have an EVM unfortunately thus I wasn't able to test on bench.

8410External_LO.tcs

Regards,

Vicente

0 ken mason 10 months ago in reply to vicente flores prado

Prodigy 160 points

Hi Vicente

Thanks for the information. I will look at the changes required, we have an EVB now so can try on that.

One other point, what is the maximum input level for the LO_M and LO_P ?

regards

Ken

0 vicente flores prado 10 months ago in reply to ken mason

TI__Mastermind 20821 points

Hi Ken,
Max input level for LO is 2Vpp.

Regards,

Vicente

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LMX8410L: NO IF output when using external LO