Comparing Schmitt Trigger with Zero Crossing Detector

| | | Zero Crossing Detector | Schmitt Trigger |
|--- |--- |--- |--- |
| | | | | 1 | It is a open loop circuit | It is a closed loop circuit with positive feedback. Hence it is also called a regenerative comparator circuit. | |
| 2 | It has only one reference i.e zero | It has two reference voltages based on the output, either Vut or Vlt | |
| 3 | Noise in the input may cause the output voltage to switch between the saturation levels. | Because of the regenerative feedback, there exists a dead band range of voltages between Vut and Vlt. Any noise coming within this band doesnt cause false changing of the output | |
| 4 | It can be used as square-wave converter for fast changing input signals | It is mostly used to convert a very slowly varying input voltage into an output having abruptly varying waveform occurring precisely at certain predetermined value of input voltage | |
| | | |