Dynamic hysteresis comparator

摘要

A dynamic hysteresis comparator has a threshold voltage level with dynamic hysteresis for sensing small changes in differential input signals at the input, while controlling a duration that an output voltage state will remain fixed for preventing the output of the comparator from changing state in an unstable fashion or “chattering”. The comparator has a dynamic hysteresis circuit connected to an output of a trigger circuit of the comparator that detects when a decision is made that a first input of the comparator is greater than or lesser than a second input of the comparator causing an output of the comparator to change state. Once the decision causing the change of state of the output is detected, any decisions determining that second input is now lesser than or greater than the first input are prevented from causing the output of the comparator from changing state for a fixed time period.

主权项

1. A dynamic hysteresis circuit connected to an output of a trigger circuit of a dynamic hysteresis comparator for detecting when a decision is made that a first input of the comparator is greater than or lesser than a second input of the comparator causing an output of the comparator to change state, and once the decision causing the change of state of the output is detected, any decisions determining that the second input is now lesser than or greater than the first input are prevented from causing the output of the comparator from changing state for at least one fixed time period for a first and a second input of the dynamic hysteresis circuit, the dynamic hysteresis circuit comprising:
a timer circuit configured to create at least one controlled time delay to control the dynamic hysteresis; and a hysteresis circuit configured to divert current from a differential input pair of transistors of the dynamic hysteresis comparator for introducing an offset such that when the offset supports the signal that caused the comparator to switch, then the dynamic hysteresis comparator is unlikely to switch back during the at least one controlled time delay that offset is applied.