Patent ID: 9479164
Filing Date: 2016-10-25
CPC Classification: G01D,G01P,G01R,H03K

Claim Text:
1. An activation circuit, comprising: a magnetic sensor configured to output a signal proportional to a measured magnetic quantity; a digital difference detection circuit configured to convert the measured magnetic quantity to a digital signal, wherein the digital difference detection circuit is configured to operate according to a low power phase and an operating phase; wherein in the operating phase the digital difference detection circuit compares a current digital signal to selected ones of previous digital signals stored in a digital storage element, to detect at least one difference in digital signals; wherein if the at least one difference in the digital signals is larger than a digital reference level, the digital difference detection circuit causes an activation signal generator to generate an activation signal that activates a system from the low power phase; and wherein the digital difference detection circuit is configured to detect an upward change or a downward change for a time, and if the time is greater than the digital reference level the activation signal generator generates the activation signal.