Embodiments of the invention include apparatus with a level-up shifter
including a comparator having a pair of cross coupled PFETs with sources
coupled to an I/O power supply and gates coupled to each other's drain,
and a differential pair of NFETs with sources coupled to ground and gates
respectively coupled to a data input and an inverted data input; and
first and second pull-up PFETs have sources coupled to a pull-up voltage
and drains respectively coupled between the differential pair of NFETs
and the pair of cross coupled PFETs. The cross coupled PFETs and
differential pair of NFETs perform level translation of low swing logic
levels at the data input to high swing logic levels on a drain of one of
the cross-coupled PFETs, while first and second pull-up PFETs speed the
level translation in response to the data input and the inverted data
input.