Compute-in-Memory ADC Code Transformation for Higher Resolution
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Solution Overview
Problem
In-memory computing components that perform analog-to-digital conversion in neural networks have limited code length and low resolution, which is undesirable for effective digital operations.
Innovation Solution
Implementing a system with dichotomous analog-to-digital converters and transform circuitry to enhance code length and resolution by applying linear and dichotomous transformations to the results of analog compute-in-memory operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard analog-to-digital converters are used in analog compute-in-memory, then the system can perform digital operations, but the code length is limited and resolution is low
Solution Approach 1:
The patent segments the code transformation process into multiple stages: first applying linear transformation to the least significant bits (LSBs), then applying dichotomous transformation to the most significant bits (MSBs). This segmentation allows the system to achieve extended effective code length (e.g., 9 bits from 5-bit ADC output) by processing different bit portions through different transformation functions, thereby resolving the contradiction between limited hardware code length and required resolution for digital operations
Solution Approach 2:
The patent changes the parameters of the code representation by applying mathematical transformations (linear and dichotomous) to convert the limited-range ADC output codes into extended-range transformed codes. The linear transformation scales and shifts the code values, while the dichotomous transformation further expands the dynamic range, effectively increasing the resolution without requiring longer physical code words from the ADC hardware
2Measurement precision
If the code length is extended through transformation, then the resolution improves, but the distribution of results must be carefully managed
Solution Approach 1:
The patent applies preliminary action by pre-determining the transformation functions (linear and dichotomous) based on the known distribution characteristics of MAC operation results. The transformation parameters are designed in advance to match the expected result distribution, ensuring that the transformed codes are evenly distributed across the extended code range. This preliminary design eliminates the need for complex real-time distribution management during operation
Solution Approach 2:
The transformation circuit acts as an intermediary between the ADC and subsequent digital processing stages. It mediates the transition from limited-resolution ADC codes to extended-resolution transformed codes by applying carefully designed transformation functions that account for the MAC result distribution, thereby simplifying the overall system operation while achieving higher effective resolution
Data Source
AI summary
An analog-to-digital converter system includes an analog compute-in-memory and transform circuitry. The transform circuitry is (i) configured to receive one or more codes from corresponding one or more analog-to-digital converters of the analog compute-in-memory, (ii) configured to provide, responsive to receipt of the one or more codes, one or more transformed codes to digital circuitry configured to perform one or more digital operations on the one or more transformed codes, and (iii) configured to determine the one or more transformed codes in accordance with a distribution of results of the analog compute-in-memory.