Method for programming a floating gate
View Patent ↗The invention provides methods for programming a floating gate. A floating gate tunneling device is used with an analog comparing device in a circuit having a floating reference node and an offset-mitigating feedback loop for iteratively programming a floating gate, or multiple floating gates.
1. A method for programming a floating gate circuit comprising the steps of:
using a level shifting device operably coupled to an analog comparing device output, providing a voltage to a tunneling device, the voltage of sufficient magnitude to induce tunneling in the tunneling device, whereby a floating reference signal is conducted through the tunneling device, the floating reference signal in turn causing a fist input signal at a first analog comparing device input to rise;
providing a second input signal to a second input of the analog comparing device until the first and second input signals become equal, whereby the analog comparing device output to the input of the level shifting device decreases, whereby the voltage at the tunneling device is changed to a level insufficient to maintain tunneling in the tunneling device;
placing feedback on the second analog comparing device input; and
causing the analog comparing device to reverse polarity, thereby placing the analog comparing device in unity gain mode, whereby the analog comparing device output, and thus the output of the floating gate circuit, is programmed at the reference signal value.
2. The method of claim 1 adapted to provide a current output signal.
3. The method of claim 1 adapted to provide a voltage output signal.
4. The method of claim 1 wherein the step of adding charge to a floating gate of the tunneling device further comprises using Fowler-Nordheim tunneling.
5. The method of claim 1 wherein the step of adding charge to a floating gate of the tunneling device further comprises using Channel-Hot-Carrier tunneling.
6. The method of claim 1 further comprising the step of independently programming one or more additional floating gates operably coupled to the analog comparing device.
7. The method of claim 1 further comprising the step of simultaneously programming one or more additional floating gates operably coupled to the analog comparing device.
8. The method according to claim 1 comprising the further steps of monitoring the output signal in order to determine whether it is a tolerably accurate representation of a selected reference signal level; and,
in the event the selected signal level is not present, reiterating the steps using an incrementally changed reference signal.
9. The method of claim 1 further comprising the step of erasing the floating gate by raising the voltage at the tunneling device to a level at which charge escapes from the floating gate.
10. The method of claim 1 further comprising the step of associating the output with an electronic system.