svensl
Full Member level 1
comparator hysteresis
Hello all,
I am currently using a simple latched comparator in a CT sigma delta ADC.
My question is with regards to deterministic and random hysteresis.
When I test the comparator and provide it with a very slowly rising ramp then, very close to the threshold, the comparator will randomly jump around a bit before it makes up its mind. This only happens when the i/p is varying very slowly, i.e. slope of 250V/s. I would imagine a similar thing happens when the i/p has spikes due to kickback noise from the comparator.
Can this be a problem in the closed loop?
Is what I am seeing random hysteresis?
When searching the net I always find comments that a hysteresis of 10% of the full range does not degrade the performance of the sigma delta much. But I am not certain that this randomness is part of a deterministic hysteresis?
Can somone please help me out on this issue.
Cheers
Hello all,
I am currently using a simple latched comparator in a CT sigma delta ADC.
My question is with regards to deterministic and random hysteresis.
When I test the comparator and provide it with a very slowly rising ramp then, very close to the threshold, the comparator will randomly jump around a bit before it makes up its mind. This only happens when the i/p is varying very slowly, i.e. slope of 250V/s. I would imagine a similar thing happens when the i/p has spikes due to kickback noise from the comparator.
Can this be a problem in the closed loop?
Is what I am seeing random hysteresis?
When searching the net I always find comments that a hysteresis of 10% of the full range does not degrade the performance of the sigma delta much. But I am not certain that this randomness is part of a deterministic hysteresis?
Can somone please help me out on this issue.
Cheers