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THS4541: Cascaded Differential Amplifiers

Jonathan Navor
Genius 9475 points
Part Number: THS4541

Hi Team, 

Good day! I am posting this in behalf of the customer. 

I have shared the full details of the inquiry here:

I am using THS4541 differential amplifier to amplify a very low-voltage signal. The max. achieved gain of THS4541 is 14 V/V, however I need a higher voltage gain. Can I use two THS4541 in serial (cascaded) to achieve a higher gain factor? I am planning to connect the differential output of the first THS4541 to the differential input of the second THS4541 and to arrange for gain 10 V/V both. In that case, can I achieve 100 V/V gain (10*10) at the output of the second THS4541 according to the input of the first THS4541? Please could you recommend/provide some technical details for getting a higher gain factor?

Best regards,

Jonathan

  • 0
    Guru 140200 points

    Hi Jonathan,

    of course, you can connect two THS4541 in series.

    But as the feedback resistance is usually 402R, increasing the gain of the first THS4541 will result in a decrease of input gain setting resistors and by this result in a decrease of input impedance. This should be kept in mind when you need input impedance matching at the first stage.

    By the way, what overall bandwidth do you need?

    Kai

  • 0
    Guru 48395 points

    Well Jonathan, the input impedance, gain, bandwidth and noise are all interelated - would need details to pursue further - start with your source impedance and what load it can drive. then total gain and desired bandwidth. I would have to go back and look at those datasheet tables I put together - probably trying to go single to diff with fixed Rf - but that is maybe not a constraint we need here - the max gain for single to diff with matched input Z can be increased by increasing the RF value. Which table are you looking at?

  • 0
    TI__Mastermind 22824 points

    Hello Jonathan,

    Are you still working on this issue?  If Michael or Kai were able to assist you with your post, you can mark the reply as 'resolved'.

    If you are still curious or have more questions, please ask and reconnect.

    Best,

    Alec