I want to design a comparator with varying hysteresis. What are the important parameters that should be considered while setting hysteresis? How can the hysteresis be modified?
you can change the hysteresis by changing the value of the positive feedback resistor
one way to do that is to put a FET across the resistor
as you turn the FET on through its linear region, the net resistance decreases
the resistor is the maximum resistance while the fully on FET represents the lowest resistance.
the hysteresis is a voltage-band defined in op-amp comparators which determines the output level based on the non-inverting input. if you won't to use hysteresis, the output will go to chattering and will be unstable. because the input is always under changes and noises.