CMOS Schmitt trigger receiver for thin oxide technology

A method of operation of a Schmitt Trigger circuit including:

• shifting, by a low-side input level shifter, a first input signal to a first shifted signal that is lower in voltage than the first input signal;
• biasing off a first transistor using the first input signal;
• biasing on a second transistor using the first shifted signal to provide a first output signal;
• shifting, by a high-side output level shifter, the first output signal to a first shifted output signal that is higher in voltage than the first output signal;
• biasing off a first hysteresis feedback transistor using the first output signal;
• and
• biasing on a second hysteresis feedback transistor using the first shifted output signal to provide hysteresis feedback control,
• wherein biasing on the second hysteresis feedback transistor comprises biasing a hysteresis feedback transistor that has one drain/source region connected to a connection between at least two series connected PMOS transistors and another drain/source region connected to one drain/source region of a PMOS cascode transistor that has another drain/source region directly connected to a reference voltage.