LTC 6404 extended voltage range


I have differential input signal with Vcm=0.9V, Vpp=1.0V i.e. actually span from 0.4V~1.4V.

I want to use LTC6404-2 with close loop gain set to 2V/V then pass the signal to AD9633 for sampling; however, this will require a span from -0.1V to 1.9V with Vcm=0.9v and Vpp=2.0V.

1. I want to know if I can make the ground of LTC6404 to be -1.0V and Vcm=0.9V with Vpp=2.0V i.e. -0.1V~1.9V differential?

2. Also, I want to know for the close loop gain of 2, whether LTC6404-1 is better or LTC6404-2?


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[edited by: JZ117 at 4:58 AM (GMT 0) on 25 Jul 2019]
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    •  Analog Employees 
    •  Super User 
    on Jul 25, 2019 6:11 PM

    Hi JZ117,

    To answer your questions about the LT6404 in the configuration you've specified:

    1. Yes, you can tie the device V- pin to -1V to allow output to swing below ground, per your conditions. You can see this arrangement implemented in LTspice within the attachment below.

    LT6404-1 CM Example

    2. For closed loop gain of 2V/V, either LTC6404-1 or LTC6404-2 would work but LTC6404-2 would be faster because it is compensated less, if that's something that matters in your application.