LEVEL SHIFTER WITH NEGATIVE VOLTAGE CAPABILITY

摘要

A level shifter circuit is presented that can apply a negative voltage level to non-selected blocks while still being able to drive a high positive level when selected. An exemplary embodiment presents a negative level shifter that is not susceptible to low voltage pfet breakdown. This allows for a high voltage level shifter (transfer gate) that can drive a negative level for unselected blocks and, when enabled for a selected block, can still drive a positive high voltage level. By using a pair of low voltage PMOS device whose n-wells share the same level as other PMOS transistors in the design, layout area can be minimized. The gates of this pair of PMOSs are connected to VSS, thereby preventing these low voltage PMOS devices from thin oxide breakdown.