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A question about THS7001

Other Parts Discussed in Thread: THS7001, LMH6502

Hello everybody. I have a question about the THS7001. The block diagram shows that there is a LPF on the output of the PGA part. However, the datasheet says nothing about the LPF's characteristics (e.g. the cut-off frequency or the frequency response). Also, I assume that there is no option to get rid of this LPF as I want to amplify DC signals too (i.e. it seems that I cannot use it as a DC amplifier). Am I right???

Best regards

George

  • Hello George,

    I did not see a filter on the block diagram.  If there is a low pass filter it would still allow DC coupled operation.  It appears that there is a voltage clamp in the block diagram.  Figure 57 on Page 21 details the clamp circuit. 

    The pre amplifier has higher bandwidth than the post amplifier (100MHz vs 70 MHz).  This way the pre amplifier does not impact the overall bandwidth.  This is not uncommon. 

    I don't see anything in the datasheet that indicates that this part cannot be used DC copuled.  

    Can you post the figure where you saw the low pass filter?

    Do you need more than 70MHz of bandwidth?  We do have faster variable gain amplifiers such as the LMH6502.

    Do you need the pre amplifier? 

    Regards,

    Loren

     

  • Hello Loren,

    First of all, I made a mistake in my initial post-question: I meant HPF (and not LPF).

    Now I see what happened. On the block diagram, the box on the output represents the "output clamping stage". I was simply misled by the "clamp symbol" inside this box. (I thought that this symbol represents an HPF.)

    I need much less BW than the 70MHz (of the 2nd stage) and I need the preaplifier. So this chip is OK for me.

    Thanks for your help.

    George

  • Hi George,

    I'm glad the THS7001 meets your needs.  Let us know if you need further assistance.

    Regards,

    Loren