This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMK1C1102: Unused differential RFOutput pins?

Part Number: LMK1C1102
Other Parts Discussed in Thread: LMX2820,

Hi folks, 

Do the unused differential RFOutput pins need to be AC couponed 50ohms to ground? Also for the LMX2820, do you need to AC-couple them to GND?



  • Hello Alpha H,

    I'm not sure you have the right part number... LMK1C1102 is a CMOS buffer, and all outputs are single-ended. Since you also mention LMX2820, I'll provide guidance for that device in both questions.

    The unused differential RFout pins do need to be AC-coupled to 50Ω load to GND, otherwise the differential pair will be unbalanced and the output will be distorted. The outputs should be AC-coupled (we recommend through 0.1µF), as the output structure of LMX2820 has a specific DC operating point at which it works best and the 50Ω load could disrupt that operating point if DC-coupled.


    Derek Payne