Buffer amplifier used in medical implants

[flabbergastt]

Hey guys, i'm new here so if i'm posting in the wrong area please let me know!

Recently at university I've had a guest lecturer that works at Cochlear developing medical implant for the hearing impaired, the guest lecturer mentioned and drew an example diagram of a buffer amplifier with 10v rail to ground supply and an input voltage between 1-10v which would mean an ideal output of 1-10v since its a buffer, the guest lecturer also mentioned about additional voltages added with Vin such that if Vin = 1v(min), an additional 0.5v would be added to it hence Vin = 1.5v... or Vin of 10v(max) = 10v + 0.5v = 10.5v ranging between 1.5v-10.5v!? Unfortunately I was unable to ask after the lecture but this has been bugging me since I have no idea why this would be useful to have additional voltage at the input in that kind of implementation?

If anyone knows please shed some light!

 

[Venkadesh_M]

They are called "Saturation Voltage"

Lower saturation voltage = negative supply + 1.5

and Upper saturation voltage = Positive supply - 1.5

In your case it is 8.5V so that the max opamp output voltage could be 8.5V

The voltage ranges are just for example purpose only, now a days the opamps are there with very low drop in voltage.

 

[flabbergastt]

They are called "Saturation Voltage"

Lower saturation voltage = negative supply + 1.5

and Upper saturation voltage = Positive supply - 1.5

In your case it is 8.5V so that the max opamp output voltage could be 8.5V

The voltage ranges are just for example purpose only, now a days the opamps are there with very low drop in voltage.

Thanks, that makes a lot of sense.
But how is that practical? and why would they need that in medical implants?

thanks!

 

[Venkadesh_M]

not only in medical implants in every place, if you use opamp the saturation will limit the output voltage.