Edge Rotator Timing Calibration for Non-Harmonic Clock Generation

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Solution Overview

Problem

In multi-radio combo-chip products, RF oscillators face challenges in avoiding frequency conflicts and injection pulling, leading to complex frequency planning and increased area and current consumption in analog circuits due to the need for good isolation and suppression of unwanted side-band spurs.

Innovation Solution

A calibration apparatus and method for an edge rotator operating on multiple phases of an oscillator, utilizing a capturing block to detect phase error samples and a calibrating block to adjust timing, along with a clock generator incorporating a delay circuit and output block to generate a non-harmonic clock signal, enabling flexible frequency planning and spur avoidance through edge selection and delay adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional analog blocks (frequency dividers and mixers) are used for frequency translation, then frequency offset ratio can be controlled, but the frequency plan becomes complicated and area consumption increases due to required isolation and spur suppression circuits

Engineering Contradiction:

Improvefrequency offset ratio controlVSAvoidfrequency plan complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces conventional analog frequency translation blocks (mixers, frequency dividers) with a digital approach using an edge rotator that operates on multiple phases of an oscillator. This substitution simplifies the frequency plan by eliminating the need for complex analog isolation and spur suppression circuits, while still achieving precise frequency offset ratio control through digital phase manipulation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The edge rotator serves multiple functions: it performs frequency translation, generates multiple clock phases, and enables flexible frequency planning for multiple radio protocols simultaneously. This multi-functionality reduces the overall device complexity by consolidating what would traditionally require separate analog blocks for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If conventional analog blocks are used for frequency translation, then frequency offset can be achieved, but area consumption and current consumption increase due to LC-tank and isolation circuits

Engineering Contradiction:

Improvefrequency offset capabilityVSAvoidcircuit area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent substitutes analog LC-tank oscillators and mixer circuits with a digital edge rotator that operates on multiple phases. This eliminates the need for large-area analog components while maintaining frequency offset capability through digital phase control, significantly reducing the overall circuit area.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If conventional analog blocks are used for frequency translation, then frequency offset can be achieved, but current consumption increases due to analog circuit requirements

Engineering Contradiction:

Improvefrequency offset capabilityVSAvoidcurrent consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces power-hungry analog frequency translation circuits with a digital edge rotator implementation. The digital circuitry consumes significantly less current than analog mixers and LC-tank oscillators, while still achieving the required frequency offset capability for multi-radio operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If timing mismatch in edge rotator is not calibrated, then circuit operation is simple, but frequency isolation and spur suppression performance deteriorate

Engineering Contradiction:

Improvecircuit simplicityVSAvoidfrequency isolation performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements a calibration mechanism that uses feedback from phase error detection to adjust and compensate for timing mismatch in the edge rotator. This feedback loop ensures that the timing alignment is optimized, maintaining excellent frequency isolation and spur suppression performance without requiring complex analog isolation circuits.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The calibration apparatus performs self-adjustment of the edge rotator timing by detecting phase errors and automatically correcting the mismatch. This self-service calibration ensures optimal performance without requiring external intervention or complex manual tuning, maintaining both simplicity and reliability.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS8816780B2Apparatus and method for calibrating timing mismatch of edge rotator operating on multiple phases of oscillator

Publication Date: 2014.08.26 MEDIATEK INC

AI summary

An exemplary calibration apparatus for calibrating timing mismatch of an edge rotator operating on multiple phases of an oscillator includes a capturing block arranged to capture phase error samples, and a calibrating block arranged to adjust timing of said edge rotator according to said phase error samples. An exemplary calibration method for calibrating timing mismatch of an edge rotator operating on multiple phases of an oscillator includes the following steps: capturing phase error samples, and adjusting timing of said edge rotator according to said phase error samples.