Crystal-Free SoC Clock Synchronization for USB Audio

Solution Overview

Problem

Conventional USB-based headphones, especially those using USB Type-C, face challenges due to the large size and high cost of processing units caused by crystal oscillators used for clock synchronization, which are essential for precise frequency generation.

Innovation Solution

A System on Chip (SoC) design that includes a digital oscillator free of a crystal, a frequency divider, and a clock synchronization calibrator, which extracts synchronization clocks from data packets and generates frequency control data to synchronize the host's clock with the USB clock, reducing the need for crystal-based oscillators and minimizing size and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a crystal oscillator is used for clock synchronization in USB-based headphones, then clock synchronization precision is improved, but the size and cost of the processing unit increase significantly

Engineering Contradiction:

Improveclock synchronization precisionVSAvoidprocessing unit size

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent replaces the mechanical crystal oscillator with a digital oscillator implemented as a software module or firmware on the USB controller. This substitution eliminates the need for physical crystal components while maintaining clock synchronization functionality, thereby reducing processing unit size without sacrificing precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses software-based clock generation that replicates the function of a crystal oscillator through digital algorithms. The USB controller generates clock signals through software routines that mimic the precise frequency generation of crystal oscillators, achieving the same synchronization precision without physical crystals

Inventive Principle:

Principle #26Copying

2Measurement precision

If a crystal oscillator is used for clock synchronization in USB-based headphones, then clock synchronization precision is improved, but the manufacturing cost increases

Engineering Contradiction:

Improveclock synchronization precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical crystal oscillator with a digital oscillator implemented as a software module or firmware on the USB controller. This substitution eliminates the need for physical crystal components while maintaining clock synchronization functionality, thereby reducing processing unit size without sacrificing precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses software-based clock generation that replicates the function of a crystal oscillator through digital algorithms. The USB controller generates clock signals through software routines that mimic the precise frequency generation of crystal oscillators, achieving the same synchronization precision without physical crystals

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If a crystal oscillator is used for clock synchronization, then frequency generation precision is improved, but the processing unit complexity increases

Engineering Contradiction:

Improvefrequency generation precisionVSAvoidprocessing unit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the clock synchronization function into the USB controller itself, eliminating the need for a separate crystal oscillator circuit. The USB controller integrates both data reception and clock generation functions, reducing overall system complexity while maintaining frequency precision through unified digital control

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the mechanical crystal oscillator with a digital oscillator implemented as a software module or firmware on the USB controller. This substitution eliminates the need for physical crystal components while maintaining clock synchronization functionality, thereby reducing processing unit size without sacrificing precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10921850B1Systems and methods for clock synchronization in transmission of audio information

Publication Date: 2021.02.16 BESTECHNIC SHANGHAI CO LTD

AI summary

Embodiments of systems and methods for clock synchronization for transmission of audio information are disclosed herein. In one example, a System on Chip (SoC) includes a Universal Serial Bus (USB) transceiver, an oscillator circuit free of a crystal, a frequency divider, and a clock synchronization calibrator. The USB transceiver is configured to extract a first synchronization clock associated with data received by the USB transceiver. The oscillator circuit free of a crystal is configured to generate an original clock. The frequency divider is configured to generate a second synchronization clock based on the original clock. The clock synchronization calibrator configured to generate a first set of frequency control data based on a frequency difference between the first synchronization clock and the second synchronization clock.