LMK1C1104EVM: question about input interface circuitry

Samaneh Afshar

Part Number: LMK1C1104EVM
Other Parts Discussed in Thread: LMK1C1104

Hello,

I greatly appreciate it if you would explain the reason of using 100 ohm resistors at the input of LMK1C1104 in the evaluation board?

Regards

Samaneh

0 Lane Boyd over 4 years ago

Hi Samaneh,

At the center node of the 100ohm voltage divider, the thevenin equivalent resistance is the parallel combination of the 100ohm resistors, or 50ohms.

This termination provides 50ohms to VCC/2, as opposed to 50ohms to GND. Ideally, this stresses the CMOS driver with equal source and sink currents.

50ohm impedance at the receiver is used to match a 50ohm transmission line

Kind regards,
Lane

0 Samaneh Afshar over 4 years ago in reply to Lane Boyd

Hi Lane,

Thank you for the clarification.

Regards

Samaneh

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