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LMK00301: Question about DC and AC circuit for LVPECL single-ended input

Part Number: LMK00301

Hi team,

        My customer want to use LVPECL single-ended as LMK00301 input, could you please help to provide the DC and AC input circuit, including the recommended value of cap and resistance? Thanks a lot!

Best Regards

Zhengquan Lu

  • Hello Zhengquan,

    Combine datasheet figures 38 and figure 25.

    Figure 38 shows an AC coupled LVPECL output driving a 50 ohm load. This is what I expect the customer's LVPECL output would look like.

    Figure 25 shows an AC coupled CMOS input signal driving the LMK00301. However the 50 ohms to ground you see in that image is the is the 50 ohm load in Figure 38.

    0.1 uF is typically a pretty good capacitor value to use for AC coupling. However for lower frequencies you may consider larger, especially below ~ 1 MHz. I suggest a capacitive reactance of less than 1 or 2 ohms.

    73,
    Timothy