Method and apparatus for high voltage generation for analog neural memory in deep learning artificial neural network
View Patent ↗Numerous embodiments are disclosed for a high voltage generation algorithm and system for generating high voltages necessary for a particular programming operation in analog neural memory used in a deep learning artificial neural network. Different calibration algorithms and systems are also disclosed. Optionally, compensation measures can be utilized that compensate for changes in voltage or current as the number of cells being programmed changes.
1. A method for generating a high voltage output in response to the number of cells to be programmed in a memory array in a single programming operation, the method comprising:
determining the number of cells in a selected plurality of cells to be programmed;
determining a first output voltage to be used in programming the selected plurality of cells;
performing a programming sequence using the first output voltage for the selected plurality of cells;
verifying which cells in the selected plurality of cells have been correctly programmed;
determining a second output voltage to be used in programming a subset of cells, the subset of cells comprising the cells in the plurality of cells that have not been correctly programmed;
performing a programming sequence using the second output voltage for the subset of cells.
2. The method of claim 1 , further comprising:
verifying which cells in the subset of cells have been correctly programmed;
determining a third output voltage to be used in programming a second subset of cells, the second subset of cells comprising the cells in the subset of cells that have not been correctly programmed;
engaging in a programming sequence using the third output voltage for the second subset of cells.
3. The method of claim 1 , wherein the step of determining a first output voltage comprises finding a value in a look-up table.
4. The method of claim 3 , wherein the step of determining a second output voltage comprises finding a value in a look-up table.
5. The method of claim 4 , wherein the step of determining a third output voltage comprises finding a value in a look-up table.
6. The method of claim 2 , wherein the step of determining a first output voltage comprises finding a value in a look-up table.
7. The method of claim 6 , wherein the step of determining a second output voltage comprises finding a value in a look-up table.
8. The method of claim 7 , wherein the step of determining a third output voltage comprising finding a value in a look-up table.
9. The method of claim 1 , wherein the step of determining a first output voltage comprises finding a value by an approximate function.
10. The method of claim 1 , wherein the step of determining a first output voltage comprises finding a value basing on current cell value and previous cell value.
11. The method of claim 1 , wherein the second output voltage is lower than the first output voltage if the number of cells in the subset of cells is less than the number of cells in the selected plurality of cells.
12. The method of claim 1 , wherein the first output voltage is applied to one or more of a source line, control gate line, and erase gate line coupled to the subset of cells.
13. The method of claim 1 , wherein the memory array is a vector matrix multiplier.
14. The method of claim 13 , wherein the vector matrix multiplier provides a neuron read out on a bit line of the memory array.
15. The method of claim 13 , wherein the vector matrix multiplier provides a neuron read out on a source line of the memory array.
16. The method of claim 13 , wherein the memory cells in the vector matrix multiplier perform weight multiplication.
17. The method of claim 13 , wherein the memory cells in the vector matrix multiplier perform synapses addition.