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lmp8672没有输出

Other Parts Discussed in Thread: LMP8672, THS6022

您好,我初次用lmp8672,给的输入信号是5MHz,5V的方波信号,供电是正负12V,为什么没有输出呢?请问这款芯片的做放大器时的参考电路是什么样的?RF和RG的取值关系如何?这些官方网站提供的datasheet上没有应用的示例。请技术支持给与帮助帮忙解决一下,谢谢!

  • Hello Ai,

    I used Google translate to make your question english.  I hope it is a good translation. 

    "Hello, I first use lmp8672, the input signal is a square wave signal to 5MHz, 5V, and the positive and negative power supply is 12V, why did not export it? Will make a reference amplifier circuit chip is what? How to value the relationship between RF and RG? There is no example of an application on the official website of the datasheet. Please help to give technical support to help solve what, thank you!"

    Can you post a schematic?  What gain and amplitude are you using?

    If you look at Figure 19 in the datasheet you can see that a 1Vpp signal of 5MHz is hitting the bandwidth limit of the amplifier.  Larger signal and square wave won't work, you will need a faster amplifier or a smaller signal.

    This part is in the precision product line, not the high speed.  I will move the post into the precision forum and maybe they can provide more information.

    Regards,

    Loren

  • Hello Ai,

    I was mistaken, this part is in the high speed portfolio. I will move this post back into our forum.

    THe LMH8672 is not fast enough for you, though. I will recommend a part that is fast enough shortly.

    Regards,
    Loren
  • Hello Ai,

    Can you look at the THS6022? That may be a better fit for your application.

    WHen calculating bandwidth requirements I use 7x for square waves. In this example, a 5MHz square wave would need at least 35MHz of bandwidth. Since it is a 5V square wave, the bandwidth needs to be large signal bandwidth.

    Regards,
    Loren
  • Hello  Loren,

    First ,I am very sorry that I didn't answer in time,and then, thank you for your prompt reply.I have looked  the THS6022.Comparing to  LMP8672,THS6022 is a better choice.But there is a problem that I need a part which could output a 5MHz ,at least 40-V p-p  signal.Although  there is a description of "These drivers can be configured differentially to drive a 50-V p-p output signal over low-impedance lines" in THS6022's datasheet , but I don't find how to do. 

    I would be grateful if you could give me some advice.

    Thank you very much!