LMX2491: Input Impedance of Fin and Fin* Pin

Hao Wang14

Expert 4415 points

Part Number: LMX2491

Hi Team,

May I know the input impedance of Fin and Fin* pins? Thanks!

Best Regards!

Hao

over 5 years ago

0 Noel Fung over 5 years ago

TI__Guru** 107780 points

Hi Hao,

The input impedance of this pin is theoretically high, that's why we put 50 ohms or a 50 ohm matching pad out front to make it match well to other environments.

0 user5200567 over 5 years ago in reply to Noel Fung

Prodigy 30 points

HI Noel

Can I understand in this way:

Almost all of input power will be absorbed by matching resistance and FIN pin just need a certain electrical level.

IF I have a external VCO, max output of VCO is very close but not up to the min required power level of FIN pin(-5dBm),

CAN I place a greater matching resistance near FIN pin and then use impedance mismatch to increase the FIN INPUT VOLTAGE LEVEL to avoid adding an amplifier?