Cross Point Array Update Method Using Segmented Voltage Pulses
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Solution Overview
Problem
Existing methods for updating cross point arrays in resistive processing units require up to four pulse cycles due to the need to handle both positive and negative values, leading to longer update times.
Innovation Solution
A method that updates a cross point array in two cycles by controlling lines with positive and negative values separately in each cycle, using a control logic to apply voltage pulses based on the applied values, allowing all devices in the array to be updated in parallel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If all values in rows and columns are updated using a stochastic update scheme with positive and negative values mixed, then the array can be updated in parallel, but up to four pulse cycles are required leading to longer update time
Solution Approach 1:
The patent segments the update process into two distinct cycles: a first cycle for updating devices based on positive values and a second cycle for updating devices based on negative values. This segmentation allows each cycle to focus on a specific subset of devices, enabling parallel updates within each cycle while reducing the total number of cycles from four to two, thus resolving the contradiction between parallel update capability and update time.
2Ease of operation
If rows and columns with positive and negative values are grouped into four categories, then all devices can be updated in parallel without interference, but the update process requires four cycles increasing time consumption
Solution Approach 1:
The patent divides the update operation into two segments (first cycle for positive values, second cycle for negative values) rather than four segments. By segmenting the control logic to handle positive and negative values in separate cycles, the patent maintains parallel update capability within each cycle while reducing the total cycle count from four to two, thereby decreasing time consumption while preserving ease of parallel operation.
Solution Approach 2:
Instead of creating four separate update cycles for the four value combinations, the patent inverts the approach by using two cycles where each cycle handles both positive and negative value updates simultaneously, but separates the control logic into distinct phases. This inversion reduces the number of cycles from four to two while maintaining the ability to update all devices in parallel without interference.
Data Source
AI summary
Disclosed a device-based cross point array and a method of operation therefor. The method relates to a method for updating a cross point array implemented as a device where a potentiation region and a depression region are separated, and the method is performed by a control logic. The method includes: in a first cycle, controlling lines where positive values are applied among first lines, in ON state, and applying a first voltage pulse at each of second lines intersecting with the first lines based on an applied value; and in a second cycle, controlling lines where negative values are applied among the first lines, in ON state, and applying a second voltage pulse at each of the second lines based on an applied value.