Duty Cycle Phase Interpolator for Precise Clock Alignment

Solution Overview

Problem

Existing clock signal interpolation methods, such as mixer-based analog interpolators, face challenges in achieving precise phase alignment due to high power and area costs, as well as significant integral non-linearity, which complicates data transmission in high-speed electronic devices.

Innovation Solution

A duty cycle-based phase interpolator circuit using pulse width modulators and state machines to produce variable duty cycle signals, allowing for adjustable phase shifts without the need for costly pre- and post-processing, and reducing integral non-linearity through specially weighted digital-to-analog converters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If mixer-based analog interpolators are used for clock signal interpolation, then phase alignment capability is achieved, but power consumption and area costs increase significantly

Engineering Contradiction:

Improvephase alignment precisionVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces the analog mixer-based system with a fully digital implementation using pulse width modulators and digital logic circuits. This substitution of analog mechanical/electrical mixing with digital pulse modulation achieves the same phase interpolation function while dramatically reducing power consumption and area requirements, as digital circuits are more power-efficient and scalable for integration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental operating parameters from analog voltage mixing to digital pulse width modulation. By representing phase information as duty cycle ratios of digital pulses rather than analog voltage amplitudes, the system achieves precise phase control through digital ratio manipulation, eliminating the need for power-hungry analog mixers and their associated pre/post-processing circuits

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If mixer-based analog interpolators are used for clock signal interpolation, then phase alignment capability is achieved, but device area increases due to power and processing requirements

Engineering Contradiction:

Improvephase alignment precisionVSAvoidcircuit area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent replaces the analog mixer-based system with a fully digital implementation using pulse width modulators and digital logic circuits. This substitution of analog mechanical/electrical mixing with digital pulse modulation achieves the same phase interpolation function while dramatically reducing power consumption and area requirements, as digital circuits are more power-efficient and scalable for integration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the unnecessary analog pre-processing and post-processing circuits that accompany traditional mixer-based interpolators. By using direct digital pulse width modulation, the system removes these extra components that consume area, leaving only the essential pulse modulators and digital logic needed for phase interpolation

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If mixer-based analog interpolators are used, then phase interpolation is achieved, but integral non-linearity increases requiring costly pre- and post-processing

Engineering Contradiction:

Improvearbitrary phase shift capabilityVSAvoidsignal processing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the analog mixer-based system with a fully digital implementation using pulse width modulators and digital logic circuits. This substitution of analog mechanical/electrical mixing with digital pulse modulation achieves the same phase interpolation function while dramatically reducing power consumption and area requirements, as digital circuits are more power-efficient and scalable for integration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent performs preliminary duty cycle adjustment directly at the pulse modulator output stage, eliminating the need for subsequent analog pre-processing and post-processing circuits. By establishing the correct duty cycle ratios early in the digital domain, the system achieves linear phase control without requiring complex corrective processing later in the signal path

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8278987B2Duty cycle based phase interpolators and methods for use

Publication Date: 2012.10.02 MICRON TECHNOLOGY INC

AI summary

Duty cycle based phase interpolators, and methods for implementing duty cycle based phase interpolators are disclosed. One such phase interpolator includes a first pulse width modulator configured to generate a first duty cycle signal, and a second pulse width modulator configured to generate a second duty cycle signal. The phase interpolator further includes a logic unit configured to merge the first duty cycle signal and the second duty cycle signal to produce a periodic digital signal with a controllable phase depending on the first and second duty cycle signals.