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.

2 comments:

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

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  2. This appears to be copied from here: http://www.nptel.ac.in/courses/117107094/lecturers/lecture_18/lecture18_page2.htm

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