Abstract: A Schmitt trigger circuit incorporates an MOS transistor connected as an inverter and two switchable currents being provided as the load to the drain of the MOS transistor to determine the switching threshold. For the low-to-high switching threshold, both currents are supplied to the transistor to require a higher gate voltage to cause the transistor to conduct both currents. Once the transistor conducts both currents and the output switches high to low, one of the sources of current is removed to cause the switching threshold to be reduced to a specified low level. The two load currents are provided by two transistors which are connected in a current mirror configuration so that the ratio of the currents provided can be precisely controlled to achieve the desired switching thresholds for the Schmitt trigger circuit.