Analog CAM Gray Code Lookup for Single-Shot Binary Output

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Solution Overview

Problem

Existing CAM and aCAM systems require separate memory arrays for storing precomputed results, leading to increased footprint and computational inefficiencies.

Innovation Solution

Implementing aCAM devices that encode decimal outputs into Gray codes and generate mappings associating ranges of decimal inputs with bit values, allowing direct output of binary codes through a single lookup operation, eliminating the need for separate memory arrays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If separate memory arrays are used to store precomputed results in CAM/aCAM systems, then the system can perform high-speed searching and computing operations, but the device footprint and area increase

Engineering Contradiction:

Improvesearching speedVSAvoiddevice footprint

Core Design Contradiction:

SpeedVSArea of stationary object

Solution Approach 1:

The patent merges the precomputed result storage function into the CAM/aCAM cell structure itself by using the content-addressable memory to directly store Gray code representations of results. This integration eliminates the need for separate memory arrays, reducing device footprint while maintaining high-speed searching capabilities through the inherent parallel search capability of CAM/aCAM structures.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The CAM/aCAM cells are designed to perform multiple functions: they store input data patterns, perform content-addressable searching, and directly output precomputed results in Gray code format. This multi-functionality eliminates the need for dedicated separate memory arrays, thereby reducing the overall device area while preserving fast search operations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If separate memory arrays are used to store precomputed results, then complete computational results can be retrieved, but computational inefficiencies and increased latency occur

Engineering Contradiction:

Improvecomputation completenessVSAvoidcomputational latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent precomputes results during the programming phase and stores them directly in the CAM/aCAM cells in Gray code format. When a search is performed, the system simultaneously retrieves the input pattern match and the precomputed result in a single operation, eliminating the need for separate computational steps and reducing latency while ensuring complete and accurate results.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

By storing precomputed results directly in the CAM/aCAM structure, the system skips the intermediate step of retrieving results from separate memory arrays and performing additional processing. The content-addressable search directly yields the final Gray code result, rushing through the computational process in a single parallel operation and minimizing latency.

Inventive Principle:

Principle #21Skipping (Rushing through)

3Quantity of substance

If separate memory arrays are used for precomputed results, then all computational data can be stored, but power consumption increases

Engineering Contradiction:

Improvedata storage capacityVSAvoidpower consumption

Core Design Contradiction:

Quantity of substanceVSUse of energy by stationary object

Solution Approach 1:

The patent combines the data storage and result storage functions into a single CAM/aCAM structure. By encoding results in Gray code and storing them within the same memory cells that store input patterns, the system maintains full computational data capacity while eliminating the additional power consumption associated with operating separate memory arrays.

Inventive Principle:

Principle #5Merging (Combining)

4Area of stationary object

If Gray codes are used to encode outputs, then the aCAM device footprint and area are reduced, but conversion to binary code is required

Engineering Contradiction:

Improvedevice areaVSAvoidcode conversion complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent replaces traditional binary encoding with Gray code encoding in the CAM/aCAM structure. Gray code requires only single-bit changes between consecutive values, which simplifies the hardware implementation of incrementors and reduces the complexity of associated logic circuits. The Gray code to binary conversion is performed through simple XOR operations, significantly reducing conversion complexity compared to traditional approaches.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12505879B2Gray encoding for analog content addressable memory in general computing

Publication Date: 2025.12.23 HEWLETT PACKARD ENTERPRISE DEV LP

AI summary

A device includes a first programmable computing block with an analog content addressable memory array, sense amplifiers, inverters, and a format converter circuit. The array includes analog content addressable memory cells arranged in rows and columns. The format converter circuit is configured to receive a Gray code from the inverters and convert it to a binary code. The device may also include additional programmable computing blocks. A system calculates decimal outputs of a predetermined function for a set of decimal inputs, encodes the outputs into Gray codes, generates mappings associating ranges of the decimal inputs with values for bit positions within the Gray codes, and programs the analog content addressable memory device based on the mappings to directly output the values for the bit positions.