Memory for programming a floating gate using an analog comparison device coupled to a tunneling device

Abstract

The present invention provides circuits, systems, and methods for programming a floating gate. As described herein, a floating gate tunneling device is used with an analog comparison 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.

We claim: 
     
       1. A circuit configured to place a selected charge on a floating gate of a tunneling device, said circuit comprising:
 an analog comparison device operatively coupled to said tunneling device; 
 a reference node operatively coupled to said tunneling device; and 
 a feedback loop configured to couple an output of said analog comparison device to an input of said analog comparison device. 
 
     
     
       2. The circuit according to  claim 1  further comprising a voltage level shifting device selectably coupled to said tunneling device, wherein said voltage level shifting device is configured to receive input from said analog comparison device. 
     
     
       3. The circuit according to  claim 1  wherein said analog comparison device has an input configured to receive a reference signal. 
     
     
       4. The circuit according to  claim 3  wherein said selected charge is provided by said reference signal. 
     
     
       5. The circuit according to  claim 1  further comprising one or more additional tunneling devices operatively coupled to said analog comparison device. 
     
     
       6. The circuit according to  claim 1  further comprising at least one power supply operatively coupled to said analog comparison device and said tunneling device. 
     
     
       7. The circuit according to  claim 1  wherein said analog comparison device comprises an op amp. 
     
     
       8. The circuit according to  claim 1  wherein said analog comparison device comprises a comparator. 
     
     
       9. The circuit according to  claim 1  wherein said analog comparison device comprises an analog to digital converter. 
     
     
       10. The circuit according to  claim 1  wherein said tunneling device comprises a Fowler-Nordheim tunneling device. 
     
     
       11. The circuit according to  claim 1  wherein said tunneling device comprises a Channel-Hot-Carrier tunneling device. 
     
     
       12. The circuit according to  claim 1  further comprising electronic power system circuitry operatively coupled with said floating gate. 
     
     
       13. The circuit according to  claim 1  further comprising portable electronic system circuitry operatively coupled with said floating gate. 
     
     
       14. A circuit configured to place a selected charge on a floating gate of a tunneling device, said circuit comprising:
 an analog comparison device operatively coupled to said tunneling device, wherein said analog comparison device has a first input configured to receive a reference signal; 
 a feedback loop configured to couple an output of said analog comparison device to a second input of said analog comparison device; 
 a reference node operatively coupled to said tunneling device; and 
 a voltage level shifting device selectably coupled to said tunneling device. 
 
     
     
       15. The circuit according to  claim 14  wherein said selected charge is provided by said reference signal. 
     
     
       16. The circuit according to  claim 14  further comprising one or more additional tunneling devices operatively coupled to said analog comparison device. 
     
     
       17. The circuit according to  claim 14  wherein said analog comparison device comprises an op amp, a comparator, or an analog to digital converter. 
     
     
       18. The circuit according to  claim 14  wherein said tunneling device comprises a Fowler-Nordheim tunneling device or a Channel-Hot-Carrier tunneling device. 
     
     
       19. A circuit for placing a selected charge on the floating gate of a tunneling device, comprising:
 an analog comparing device having a first input operably coupled to the output of a tunneling device, the analog comparing device also having a second input selectably coupled to a reference signal;   a level shifting device selectably coupled to the input of the tunneling device, the voltage level shifting device also operably coupled to receive input from an analog comparing device output;   wherein the input of the tunneling device is selectably coupled to a reference node; and wherein a selected charge provided by the reference signal is placed on the floating gate of the tunneling device.   
     
     
       20. 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 first 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; 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.