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LMH6521 Tina ti model

Other Parts Discussed in Thread: LMH6521, TINA-TI, LMH6517, LMH6518, LMH6881

HI i have recently encountered an issue with LMH6521 for my oscilloscope design project.

How accurate is the spice model for this part?  I am asking This  because on TINA TI simulation the amplifier works for low frequencies as I would like it , but in the Datasheet it is explained that the amplifier is optimized to work for higher frequencies(> 3MHz).   i haven't physically tested it but is there a chance that the model could be wrong and the part actually will not work for low frequencies?  


  • Hello Abel,

    The tina ti spice model for the LMH6521 is pretty accurate. The comment in the datasheet that the amplifier is optimized to work for higher frequencies greater than 3MHz is incumbent on the use of 1uH inductors from the output pins to ground for a Class-A style output biasing. You can make it work for lower frequencies by increasing the value of this inductor, but there is a limit on the inductor size and value, and for oscilloscope application, you would certainly want to operate the amplifier till dc.

    The way you can dc couple the LMH6521 output is using resistors instead of inductors for dc coupling the LMH6521 output; but the trade-off is that you would need to be able to provide negative supply voltage. I have attached the TINA-TI file of the LMH6521 used in DC coupled output application done by one of our experts and only the top channel has been modified to work in this application. 7002.LMH6521 DC Coupling RevB.TSCI would also recommend using the LMH6517,  LMH6518 or the LMH6881/2 instead of LMH6521 which are more optimized to be used in an oscilloscope application.

    Best Regards,


  • Hello Abel,

    For more information see the TI Design paper that gives more details.