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AD4817-2 use as a multiplexor

Question asked by BartSchroder on Apr 1, 2012
Latest reply on Sep 16, 2015 by BartSchroder

Hello,

We are planning to use the ADA4817 1GHz Fast fet op-amp (amazing device that it is!). We would like to use it as a 2:1 multiplexor.

We note that it can be powered down (with Iq = 1mA), however there is no information on the output topology when powered down.

 

Assuming that we will have a series resistor between each output and a common summing point (which happens to be a ADA4939 differential amplifier), do you have any idea about the following points:

1. What is the load presented by the powered-down op-amp output (as in R//C) ?

2. If the output is a relatively low impedance (ie 100 - 1k), how variable is it from device to device and over temperature

2. What is the effective output noise (nV/rtHz would be good) for a powered down op-amp?

 

Thanks for any help.

 

Bart Schroder

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