Patent ID: 6815983
Filing Date: 2004-11-09
Classification: G11C,H03K

Abstract:
A method for sensing the voltage on a floating gate while charge is being stored thereon in a floating gate circuit to enable programming of said floating gate to a precise voltage, said floating gate circuit including a differential circuit having a first transistor configured as an inverting input of said differential circuit, wherein said floating gate is the gate of said first transistor, a second transistor configured as a non-inverting input of said differential circuit, and a differential circuit output, said floating gate circuit further including a feedback circuit coupled from said output to said floating gate, said method comprising the steps of:a) causing said floating gate circuit to enter into a set mode, wherein a predetermined voltage is coupled to the gate of said second transistor; b) causing the voltage on said floating gate to be sensed by said first transistor relative to said predetermined voltage; c) causing an output voltage to be generated at said differential circuit output; d) causing the voltage on said floating gate to be modified as a function of said output voltage using said feedback circuit, including modifying the charge level on said floating gate under the control of a first tunnel device and a second tunnel device operating in dual conduction during said set mode, said first tunnel device formed between said floating gate and a first tunnel electrode and said second tunnel device formed between said floating gate and a second tunnel electrode; and e) repeating of steps b) through d) until said floating gate circuit settles to a steady state condition such that the voltage on said floating gate is approximately equal to said predetermined voltage.