Current sharing / Ideal Diode ORing on 1.1V rail

[veryevil]

I'm trying to come up with a way to current share a 1.1V rail. I have a design with up to 6 plug in cards each which generate a 1.1V supply which I would like to use on the backplane the 6 cards are plugged into.

This would be for fault tolerance and also reduced loading of all the individual cards.

This is easy at higher voltages but I'm struggling to come up with a way to do it at such a low input voltage

Coupled with the lack of available chips this is really got me stumped

I do have 5v and 3v3 available too if there is a chip I can use with vcc higher but 1.1v as the pass through

Any thoughts? 

Output current would only be an 1A at 1.1V

[David Hess]

So each card generates a 1.1 volt supply, and you want to interconnect it between cards so that if power is lost to one of the cards, the other cards will power it?

The forward voltage drop of diodes is obviously a problem at such low voltage.  At such low voltages, bipolar transistors can be used to sort of make diodes with no forward voltage drop by biasing the base with sufficient current, and there is probably some way to improve that.  This only works at low voltages because the reverse breakdown voltage of the base-emitter junction is only like 5 volts.

1 amp is not all that much.  If the 1.1 volt supplies are regulated closely enough, then they can be connected directly in parallel and rough current sharing will be enforced by the series resistance between the sources, or 10s of milliohms of series resistance can be added at each output.

I am dubious about sharing such a low voltage between cards.  Better might be to share a slightly higher and not as tightly regulated voltage, and implement 1.1 volt regulation on each card.