LMX2492 Fin Topology

Nikhil Konaraddi59

Other Parts Discussed in Thread: LMX2492

Hi TI team,

I would like to know the maximum and minimum power that can be fed differentially into the Fin and Fin* terminals. In the datasheet, for a single ended operation it is mentioned to be between -5dBm to 5dBm.

In my system, the VCO divider output has a differential power between -9dBm and 0dBm at 200Ohm output impedance. Would it be possible to feed such a signal into Fin and Fin* pins of LMX2492. If not, do you recommend some suggestions here?

Thanks

Nikhil

over 7 years ago

0 Dean Banerjee over 7 years ago

TI__Mastermind 28031 points

Nikhil,
We test to -5 to +5 dBm single-ended. If you use a differential signal, then I would expect it to be 6 dB lower as -11 to -1 dBm.

Regards,
Dean

0 Nikhil Konaraddi59 over 7 years ago in reply to Dean Banerjee

Prodigy 150 points

Hello Dean,

Thanks for the reply. The output divider from the VCO is 200Ohm differential. I see that the Fin and Fin* pins are 50Ohm single ended. Can you comment on what is the differential impedance of Fin and Fin* ?

BR
Nikhil

0 Dean Banerjee over 7 years ago in reply to Nikhil Konaraddi59

TI__Mastermind 28031 points

Nikhil,

The input impedance of this pin is theoretically high, but we put 50 ohms or a 50 ohm matching pad out front to make it match well to other environments. Typically, this would mean 100 ohm differential, but if your VCO is 200 ohms, then you probably want to put 200 ohm accross this to match.

Regards,
Dean

0 Nikhil Konaraddi59 over 7 years ago in reply to Dean Banerjee

Prodigy 150 points

Hello Dean,

Thanks for the answer.

Nikhil

Clock & timing

Clock & timing forum

LMX2492 Fin Topology