Calibration of a flexible high precision Power-On Reset during production test

This paper describes a Power-On Reset (POR) circuit with very accurate threshold voltage levels. These voltage levels are achieved by calibrating an on-chip programmable voltage reference during the wafer sort or final test. Two different calibration methods are proposed. One which calibrates the reference voltage of a comparator and another method which calibrates the POR threshold voltage levels itself. Not only the variation of the POR threshold voltage levels can be reduced from 90mV to 7mV, but also the absolute value can be changed.