Non-inverting Schmitt trigger - An introduction

Introduction: The section below is the detailed explanation of the Non-inverting Schmitt Trigger.

Non-inverting Schmitt trigger:

  • In the case hereby, feedback is provided at the non-inverting terminal.
  • The inverting terminal is here grounded and along with this, the input voltage is apparently connected to the non-inverting input. fig1. 1, depicts a non-inverting Schmitt trigger circuit.

Fig. 1.1
  • For the circuit behavior analysis, lets make an assumption that the produced output is saturated negative.
  • Then the feedback voltage is also negative (-Vsat). Then the feedback voltage is also negative.
  • This feedback voltage will hold the output in negative saturation until the input voltage becomes +ve as much as required to result into making voltage positive.

  • When vin  turns to be positive and eventhe magnitude is higher than than (R2 / R1) Vsat, then in such a case, the output turns to +Vsat.
  •  Therefore, the UTP at which the output switches to +Vsat, is given by

  • Similarly in the case wherein the output is at the saturation that is positive, feedback voltage is definitely positive.
  • To turn out to the output states, then input voltage has become negative enough to make.
  • When it happens, the output amends to the negative state from positive saturation to negative saturation voltage negative.


  1. why the direction of hysteresis is taken as anticlockwise??

  2. This appears to be copied from here: