I am confronted with interfacing separate DAC outputs of a PIC to 1M and 100K impedance inputs on other devices. This is a DC system. I need the full swing of 0V to 3V. Also I would like a single supply here-I have a 0/5V system. I am leery of direct connection to the PIC-it is advised against by Microchip.

An ordinary single supply opamp or BJT source follower won't don't here due to the offset floor. Maybe a rail to rail op/amp would do.
How about a matched pair FET-I think that gives no offset yes?

Wondered how others solve this problem-any comments appreciated-

fritz

 

Best would likely be a good rail-rail op amp in a non-inverting follower configuration. With a 5V supply they will go from essentially 0V to a full 3V output.

Matched-pair FETs are not likely a good choice for this.

 

Thanks for the reply. I ordered a few TLV2772AIP amps a few days ago and was hoping to test them soon. I think these comply with your advice.

cheers
Fritz