Crystal Oscillator Energy Injection Using Resonance Feedback

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Solution Overview

Problem

Existing crystal oscillators face challenges in efficiently injecting energy due to their high quality factor, which requires the injection frequency to be very close to the resonant frequency, leading to ineffective energy injection when it is far from the resonant frequency and consumption of existing energy.

Innovation Solution

An apparatus comprising a voltage-controlled oscillator, a ramp voltage generating circuit, a switch, and a control circuit that detects the current through the crystal to switch the control voltage and adjust the oscillation signal frequency to match the resonant frequency, ensuring efficient energy injection into the crystal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a swept-frequency clock is used to inject energy into the crystal, then the startup speed of the crystal oscillator is improved, but when the injection frequency is far from the resonant frequency, the energy injection is ineffective and existing energy is consumed

Engineering Contradiction:

Improvestartup speedVSAvoidenergy consumption

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The patent employs a feedback mechanism where the control circuit monitors the current through the crystal and uses this information to adjust the injection frequency. The control circuit detects when the current reaches a maximum value, indicating resonance, and switches the control voltage accordingly. This feedback loop ensures that energy is injected at the optimal frequency, preventing wasted energy while maintaining fast startup performance.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically adjusts the control voltage of the voltage-controlled oscillator based on the detected current through the crystal. Instead of using a fixed swept-frequency approach, the system continuously adapts the injection frequency in real-time based on the crystal's resonant conditions. This dynamic adjustment ensures energy is always injected at the optimal frequency point, resolving the contradiction between fast startup and energy efficiency.

Inventive Principle:

Principle #15Dynamics

2Loss of energy

If the injection frequency is very close to the resonant frequency of the crystal, then energy is effectively injected into the crystal, but this requires precise frequency control which increases system complexity

Engineering Contradiction:

Improveenergy injection efficiencyVSAvoidfrequency control complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent enables the system to self-adjust the injection frequency by using the crystal's own resonant response as the control signal. The current through the crystal naturally indicates when resonance is achieved, and this self-generated signal is used to switch the control voltage. This eliminates the need for complex external frequency control mechanisms, achieving precise frequency matching through the system's inherent properties.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the control voltage parameter of the voltage-controlled oscillator based on the detected current conditions. By switching between different voltage levels (first voltage when current is increasing, second voltage when current reaches maximum), the system dynamically adjusts the injection frequency to match the resonant frequency. This parameter-based control approach simplifies the overall system while achieving precise frequency control.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables efficient energy injection into the crystal, improving the startup speed of the crystal oscillator by ensuring the energy injected is sufficient and maximized when the frequency is close to the resonant frequency.

Implementation Method 1

a voltage-controlled oscillator configured to output an oscillation signal to the crystal

Methodology Applied

Scientific EffectVoltage-controlled oscillation:

Implementation Method 2

a control circuit configured to control a status of the first switch according to a current through the crystal

Methodology Applied

Scientific EffectElectrical current detection:

Implementation Method 3

when the injection frequency is very close to a resonant frequency of the crystal

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS11689158B2Apparatus for injecting energy into crystal in crystal oscillator, and crystal oscillator

Publication Date: 2023.06.27 SHENZHEN GOODIX TECH CO LTD

AI summary

Embodiments of the present application provide an apparatus for injecting energy into a crystal in a crystal oscillator, and a crystal oscillator. The apparatus includes: a crystal; a voltage-controlled oscillator configured to output an oscillation signal to the crystal; a ramp voltage generating circuit configured to generate a ramp voltage that changes over time; a first switch disposed between the ramp voltage generating circuit and the voltage-controlled oscillator; a first capacitor, where a first terminal of the first capacitor is connected to the first switch and the voltage-controlled oscillator, and a second terminal of the first capacitor is grounded; and a control circuit configured to control a status of the first switch according to a current through the crystal. Therefore, the apparatus can efficiently inject energy into the crystal.