Current Mode DAC Array for MAC Power Reduction

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Solution Overview

Problem

Existing hardware systems performing MAC operations face inefficiencies due to non-linear conversions by voltage mode DACs and voltage-to-current conversions, leading to increased power consumption and the need for additional filters, which also consume power and increase device size.

Innovation Solution

The implementation of a device using current mode digital-to-analog converters (DACs) with a radio frequency (RF) current source, which allows for a large number of memory elements to be integrated with low power consumption, eliminates the need for intermediate frequency conversion, and provides direct interface with non-volatile memory elements without additional bias current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If voltage mode DACs are used for MAC operations, then digital-to-analog conversion can be performed, but non-linear conversions and voltage-to-current conversions increase power consumption and require additional filters

Engineering Contradiction:

Improvepower consumptionVSAvoiddevice complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the voltage mode DAC and voltage-to-current conversion stages from the system. By directly using current mode DACs, the invention removes the non-linear conversion components that caused power consumption issues and the need for additional filtering, thereby resolving the technical contradiction between power consumption and device complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes voltage mode operation with current mode operation throughout the MAC array. This replacement eliminates the need for voltage-to-current conversions and associated filters, directly reducing both power consumption and device complexity while maintaining the required functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If voltage mode DACs with filters are used, then conversion accuracy can be maintained, but device size increases due to additional filters

Engineering Contradiction:

Improveconversion accuracyVSAvoiddevice size

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent removes the filter components from the system by eliminating the voltage mode DAC architecture. Current mode DACs inherently provide the necessary signal conditioning without requiring external filters, thus maintaining conversion accuracy while reducing device size.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

By substituting voltage mode with current mode operation, the patent eliminates the need for separate filtering stages. The current mode architecture naturally provides the required signal integrity, allowing the system to maintain conversion accuracy without the additional area overhead of filters.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If intermediate frequency conversion is used, then signal processing can be performed, but power consumption increases and conversion steps are added

Engineering Contradiction:

Improvesignal processing efficiencyVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent extracts and eliminates the intermediate frequency conversion stage from the MAC operation pipeline. By using current mode DACs that operate directly at the target frequency, the invention removes the additional conversion steps while maintaining signal processing capability, thereby reducing power consumption without sacrificing productivity.

Inventive Principle:

Principle #2Taking out (Extraction)

4Adaptability or versatility

If additional bias current is used for memory interface, then non-volatile memory can be interfaced, but power consumption increases

Engineering Contradiction:

Improvememory interface capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent substitutes voltage mode operation with current mode operation at the memory interface. This substitution allows direct interfacing with non-volatile memory elements using the same bias current that flows through the MAC array, eliminating the need for additional bias current while maintaining full memory interface capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11315613B2Mixed mode multiply and accumulate array

Publication Date: 2022.04.26 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

Systems and methods for operating a digital-to-analog converter (DAC) are described. In an example, a device can receive a digital input. The device can generate a clock signal having frequency in radio frequency (RF) range. The device can combine the digital input with the clock signal to generate a first voltage signal. The device can convert the first voltage signal into a second voltage signal having at least two phases. The device can convert the second voltage signal into a current signal. The device can distribute the current signal to at least one current mode DAC.