Ultra-Low Voltage Schmitt Triggers Implemented by HfO2-Based Ferroelectric Field-Effect Transistors

In this letter, a simple ultra-low voltage Schmitt trigger is demonstrated. It consists of an HfO2-based ferroelectric field-effect transistor (FeFET) and a load transistor, which greatly simplifies the circuit design and reduces the power consumption in contrast with traditional Schmitt trigger with four to six transistors. The Schmitt trigger has two different threshold voltages without fluctuation at different supply voltages and it can still be operated even at 10 mV. Waveform transformation is successfully implemented through the Schmitt trigger and the output square waveform is obtained even with V-dd = 10 mV. The Schmitt trigger can also perform logic-state transition under input pulse with width down to 20 ns, which may be considered for the realization of logic-in-memory applications. This multifunctional device demonstrates advantages in simple circuits and low voltage, showing great potential in ultra-low power integrated circuit applications such as wearable systems and bio-implantable microcircuits.