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LMH3401 Gain vs bandwidth

John Heitke
Prodigy 160 points
Other Parts Discussed in Thread: LMH3401

I am using several LMH3401 amplifiers in a signal distribution application.  I have 2 amplifiers back to back and am wondering about the affect on bandwidth that increasing the gain of the second stage by driving the input directly from the first stage or with 2.5 ohm series resistors for an ideal output to input impedance match.  The interconnect distance between the amplifiers is negligible so there is no PCB transmission line impedance matching to consider.

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    TI__Genius 13935 points
    Hello John,

    The datasheet Figure 3 shows plots with the LMH3401 driven with 50 Ohm source resistance. The BW should be very close for the second stage as you describe it since the LMH3401 has a 20 Ohm internal source resistance. With two stages in cascade the overall bandwidth will still be reduced over a single amplifier.

    One of my projects is to build a board with two LMH3401 amplifiers in cascade, but I have not completed it yet. I will be posting the results in a reference design later this summer.

    Regards,
    Loren