USB Device Frequency Calibration Using Host LFPS

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Solution Overview

Problem

The high manufacturing cost of USB 3.0 devices is attributed to the large chip area occupied by traditional precise inductor capacitor oscillators, which are necessary for generating a precise reference clock.

Innovation Solution

A frequency calibration method for USB devices that utilizes a low frequency periodic signal from a USB host to calibrate a programmable oscillator, eliminating the need for a built-in precise inductor capacitor oscillator by extracting and processing the low frequency periodic signal to generate a predetermined frequency oscillating signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a precise inductor capacitor oscillator (LC oscillator) is built in a USB 3.0 device to generate a reference clock, then the frequency precision is improved, but the chip area occupied increases significantly

Engineering Contradiction:

Improvereference clock frequency precisionVSAvoidchip area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent introduces a low frequency periodic signal (LFPS) from the USB host as an intermediary reference to calibrate the programmable oscillator. Instead of relying on a large LC oscillator, the system uses the LFPS as a mediator to achieve frequency calibration, thereby reducing chip area while maintaining precision

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the frequency parameter by using a low frequency periodic signal (e.g., 100 kHz) to calibrate a programmable oscillator that generates higher frequency clocks (e.g., 24 MHz, 100 MHz, 2.5 GHz). This parameter transformation allows achieving high precision reference clocks without requiring large LC oscillators

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If a precise inductor capacitor oscillator (LC oscillator) is built in a USB 3.0 device, then the reference clock precision is improved, but the manufacturing cost increases

Engineering Contradiction:

Improvereference clock frequency precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive LC oscillators with cheaper programmable oscillators that can be calibrated using low frequency periodic signals from the USB host. This substitution significantly reduces manufacturing costs while maintaining the required frequency precision for USB 3.0 operations

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The LFPS from the USB host serves as a free intermediary calibration reference, eliminating the need for expensive built-in LC oscillators. The host's LFPS is used to calibrate the device's programmable oscillator, reducing component costs

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10635129B2Frequency calibration method applicable in universal serial bus device and related universal serial bus device

Publication Date: 2020.04.28 SILICON MOTION INC

AI summary

A frequency calibration method applied to a Universal Serial Bus (USB) device includes: coupling the USB device to a USB host, wherein the USB device comprises at least a programmable oscillator; utilizing the USB device to extract a low frequency periodic signal from the USB host; calibrating the programmable oscillator of the USB device according to the low frequency periodic signal, to make the programmable oscillator generate an oscillating signal having a predetermined frequency; and when the USB device receives the low frequency periodic signal from the USB host, controlling the USB device to generate a predetermined signal having a frequency higher than a frequency of the low frequency periodic signal to the USB host, to make the USB host continuously generate the low frequency periodic signal to the USB device.