LMK1C1106: Application issues of chips

Hi Tony,

Output impedance of this buffer is 50 ohm. This resistor should be 0 ohm to match the trace impedance.

Best,

Asim

I'll add that the structure of the LMK11xx LVCMOS output buffer actually includes a series resistance built into the output stage that is designed to complement the impedance of the driver FETs to make a nominal 50Ω impedance. This diagram is likely copied from a previous LVCMOS buffer that did not include a series resistance in the output stage, where the output impedance might have been closer to 25Ω - in these cases a series resistance of 22Ω, 27Ω, or 33Ω might have been suggested to help match 50Ω source impedance. LMK1106 and other similar-family LMK11xx parts do not require a series resistance, and that component may be omitted.