Charge-Based Analog Correlators Using Margin Propagation

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Solution Overview

Problem

Conventional analog correlators face challenges in achieving energy-efficient correlation operations due to limited resolution, high power consumption, and area inefficiency, particularly in digital multiply-and-accumulate (MAC) based architectures, and in-memory analog computing with variable conductance, which are limited by noise and array size trade-offs.

Innovation Solution

A non-multiply-accumulate (non-MAC) charge-based analog correlator system comprising a sampler circuit, operand generation circuit, and margin propagation (MP) correlation computation circuit, which operates in the charge domain to generate correlated output signals, eliminating the need for analog-to-digital converters and improving power and area efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If digital MAC based architecture is used, then computing accuracy is improved, but power consumption and area increase

Engineering Contradiction:

Improvecomputing accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by stationary object

Solution Approach 1:

The patent replaces digital MAC operations with an analog charge-based computation system. The sampler circuit converts input signals to charge domains, and the margin propagation circuit performs correlation computations using charge accumulation and comparison, eliminating the need for digital multiplication and accumulation operations. This substitution achieves comparable computing accuracy while significantly reducing power consumption by operating in the analog domain without requiring ADCs for each operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Use of energy by stationary object

If in-memory analog computing with variable conductance is used, then power consumption is reduced, but resolution is limited by noise and array size trade-offs

Engineering Contradiction:

Improvepower consumptionVSAvoidresolution

Core Design Contradiction:

Use of energy by stationary objectVSMeasurement precision

Solution Approach 1:

The patent introduces a margin propagation mechanism as an intermediary between the analog charge domain and the output. The sampler circuit acts as an intermediary that converts input signals to charge domains with controlled impedance, and the margin propagation circuit uses charge accumulation and comparison to achieve high-resolution results. This intermediary approach allows the system to overcome the noise limitations of direct in-memory computing while maintaining low power consumption, achieving both high resolution and energy efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by stationary object

If analog-to-digital conversions are eliminated, then power consumption is reduced, but correlation length is limited to about 10 samples

Engineering Contradiction:

Improvepower consumptionVSAvoidcorrelation length

Core Design Contradiction:

Use of energy by stationary objectVSLength of moving object

Solution Approach 1:

The patent transitions from time-domain sampling to charge-domain accumulation, adding a dimensional transformation to the computation process. The margin propagation circuit accumulates charge over multiple samples in the charge domain, enabling correlation lengths up to 1024 samples without requiring ADCs. This dimensional change from discrete time samples to continuous charge accumulation allows the system to achieve long correlation lengths while maintaining analog operation and low power consumption.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Productivity

If matrix multiplication in compute-in-memory cores is used, then correlation computation is achieved, but operating speed is very low for multi-bit inputs

Engineering Contradiction:

Improvecorrelation computationVSAvoidoperating speed

Core Design Contradiction:

ProductivityVSSpeed

Solution Approach 1:

The patent employs periodic sampling and charge accumulation cycles in the margin propagation circuit. The sampler circuit periodically samples input signals and converts them to charge domains, and the margin propagation circuit performs periodic charge accumulation and comparison operations. This periodic action enables the system to achieve high operating speeds for multi-bit inputs by processing data in efficient cycles rather than requiring slow sequential matrix multiplication operations, thereby improving productivity while maintaining analog operation.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS12580577B2Scaling-friendly, analog correlators using charge-based margin propagation

Publication Date: 2026.03.17 THE STATE OF OREGON ACTING BY & THROUGH THE OREGON STATE BOARD OF HIGHER EDUCATION ON BEHALF OF OREGON STATE UNIV

AI summary

A non-multiply-accumulate (non-MAC) charge-based analog correlator system including a sampler circuit block, an operand generation circuit block, and a margin propagation (MP) correlation computation circuit block is disclosed. The sampler circuit block is configured to sample a plurality of input analog signals. The operand generation circuit block is configured to generate operands based on the sampled plurality of input analog signals, and the margin propagation (MP) correlation computation circuit block is configured to generate correlated output signals based on the operands and using calculations in a charge domain.