The two stages 201 , 211 together provide sensing at low voltage levels of the V.sub.dd signal since only a single threshold drop is required for operation, thereby providing for maximum headroom.
The sense amplifier 200 operates at voltages as low as 1.8 volts for correct operation, including supply voltages of 1.8 , 2.0 , 2.4 or 3.0 volts or higher.