what technology does it use? TTL or ECL like that. i think only ECL logic has a negative reference voltage. for it to not enter the saturation region. that is all i am able to resolve abt this problem. but, anyother person could help with this question. seems a good question.
I think you could use an OP Amp to invert the voltage, but this solution will drop more current from the supply and you need positive and negative supply.
Be aware, there is an error in this application note.
The application note is about MAX828, but at the schematic it says MAX826.
Just use a MAX828, there is no IC called MAX826, it's just a typing error.