Patent ID: 7345522
Filing Date: 2008-03-18
Classification: G11C,H03K

Abstract:
1. In a reference voltage generator that includes a floating gate that stores a charge corresponding to a predetermined input set voltage, a first device formed between said floating gate and an erase electrode for removing charge from said floating gate and a second device formed between said floating gate and a program electrode for coupling charge to said floating gate, a method for stabilizing the charge on said floating gate comprising the steps of: causing said erase electrode to be biased by a first bias source during a set mode; causing said program electrode to be biased by a second bias source during said set mode; causing the voltage on said floating gate to be compared to said input set voltage and generating an output voltage at an output terminal as a function of the difference between said input set voltage and said floating gate voltage; providing a feedback circuit for causing the voltage on said floating gate to be modified as a function of said output voltage until the voltage on said floating gate is a predetermined function of said input set voltage during said set mode; and in response to said feedback circuit causing said output voltage to be approximately equal to said input set voltage, causing the voltages at said erase and program electrodes to ramp down at a predetermined rate such that, when said first and second bias sources are turned off, said floating gate is charged to a charge level that is a predetermined function of said input set voltage.