Selective Inverter Signal Paths for Duty Cycle Aging Control

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Solution Overview

Problem

High-speed circuits, such as DDR memory devices, suffer from negative-bias temperature instability due to prolonged periods of a signal being in one state, leading to duty cycle distortion and timing errors, which existing solutions like dummy toggling address inefficiently by consuming significant power.

Innovation Solution

The implementation of selective inverters in integrated circuits that control signal states to counteract aging effects by introducing timing errors of opposite polarities in separate circuit paths, thereby reducing duty cycle distortion without the power consumption associated with dummy toggling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If dummy toggling is used to counteract aging effects, then duty cycle stability is improved, but power consumption increases significantly

Engineering Contradiction:

Improveduty cycle stabilityVSAvoidpower consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The circuit is divided into multiple signal paths (first circuit path and second circuit path) with different aging characteristics. Each path processes the same clock signal but experiences opposite aging effects, allowing the system to segment the aging problem and combine results to achieve stability without power-intensive dummy toggling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a selective inverter that inverts the clock signal in one circuit path during idle periods. This inversion causes the second circuit path to experience opposite aging effects compared to the first path, so that when both paths are combined, the aging effects cancel each other out, maintaining duty cycle stability without continuous toggling.

Inventive Principle:

Principle #13The other way round (Inversion)

2Use of energy by moving object

If signals remain in one state for extended periods, then power consumption is reduced, but negative-bias temperature instability causes duty cycle distortion

Engineering Contradiction:

Improvepower consumptionVSAvoidduty cycle stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

Different circuit paths are given different signal states locally - the first circuit path receives the original clock signal while the second circuit path receives an inverted signal during idle periods. This local differentiation ensures that one path experiences aging in one direction while the other experiences aging in the opposite direction, maintaining overall duty cycle stability without requiring both paths to continuously toggle.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10110229B1Aging-resistant signal path circuitry

Publication Date: 2018.10.23 ALTERA CORP

AI summary

Systems and methods are related to selectively inverting circuit paths of an integrated circuit to reduce errors due to aging. An integrated circuit includes a first circuit path that receives an input signal and outputs a first output signal, a first selective inverter that receives the first output signal and outputs a first inverter output signal; and a second circuit path that receives the first selective inverter output signal and outputs a second output signal. In a first mode, the first selective inverter does not invert the first output signal and outputs the first output signal as the first selective inverter output signal. In a second mode, the first selective inverter inverts the first output signal and outputs an inverse of the first output signal as the first selective inverter output signal.