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THS4513-SP: gain

Adam Daluga
Expert 6135 points
Part Number: THS4513-SP
Other Parts Discussed in Thread: THS4513

  I have a question about the discrepancy with the THS4513-SP gain: 

The datasheet found here

 

https://www.ti.com/lit/ds/symlink/ths4513-sp.pdf?ts=1635871759485&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTHS4513-SP

 

lists a minimum gain of 2V/V.

 

However, the table found here (TI space products guide)

  

says it is ok with a gain of 1, and the commercial part datasheet also says it is ok with a gain of 1.  Do you know which is right?  Can the space part be used with a gain of 1, and if yes do you recommend the values in the commercial datasheet shown below?

 Thanks,

Adam

  • 0
    TI__Mastermind 26485 points

    Hello Adam,

      The THS4513-SP is not a decompensated device, so technically it should be stable at unity gain. It's catalog part THS4513 is specified at unity gain which you have already noticed. However, most likely due to the different packaging, the parasitics affected the open loop crossover of the device causing instability and peaking in the ac response at unity gain which is the reason the space datasheet highly recommends a gain of 2. Would it possible to use an attenuator at the output of the amplifier?

    Thank you,

    Sima 

  • 0
    Guru 48395 points

    Morning Adam, 

    You can use any part at any gain with external compensation. As Sima says, this is a phase margin issue which then would also bring the load into the question. I doubt there is a seperate model for the SP version package. 

    Anyway, here is a discussion of FDA stability simulation and compensation, if you can provide your circuit, easy to test in TINA, The part 5 is sort of the start of this discussion. 

    https://www.planetanalog.com/stability-issues-and-resolutions-for-high-speed-fully-differential-amplifiers-fdas-insight-8/