Crystal Oscillator Mode Switching for Low-Jitter, Low-Power Clocks
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Solution Overview
Problem
Modern electronic devices face stringent reference clock jitter requirements due to increased modulation schemes and bandwidth, leading to higher current consumption, which is inefficient for battery-powered platforms, especially for legacy modulation schemes.
Innovation Solution
A crystal oscillator design that allows operation at both fundamental and overtone resonance frequencies, enabling power/performance optimization through a suppression circuit and control circuit that selectively couples the suppression circuit to the crystal resonator, allowing on-the-fly switching between modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher current is invested to improve oscillator noise performance for higher modulation schemes, then jitter performance is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic operation mode switching between fundamental and overtone resonance frequencies based on communication requirements. The system transitions from static to dynamic operation, adjusting the oscillation frequency mode according to whether high-performance modulation schemes are being used, thereby optimizing the trade-off between jitter performance and power consumption in different operational contexts
Solution Approach 2:
The patent changes the operating parameter (resonance frequency mode) of the crystal oscillator between fundamental and overtone modes. By switching the oscillation frequency parameter, the system can achieve low-power operation during transitions and legacy mode compatibility while maintaining the ability to deliver high performance when needed, thus resolving the contradiction between power consumption and jitter performance
2Use of energy by moving object
If operation switches between fundamental and overtone modes, then power optimization is achieved, but mode transition stability may be affected
Solution Approach 1:
The patent employs a delay element that introduces a controlled time delay during mode transitions. This preliminary timing adjustment ensures that the suppression circuit is activated or deactivated at the optimal moment, allowing the oscillator to complete its current cycle before switching modes, thereby maintaining stability during transitions and preventing abrupt changes that could disrupt operation
Solution Approach 2:
The suppression circuit is designed to gradually enable or disable rather than switch instantaneously. This cushioning approach prevents sudden energy injection or removal that could cause instability, allowing the system to transition smoothly between modes while maintaining operational stability and preventing glitches in the output signal
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 design achieves efficient power management and improved jitter performance by allowing operation at higher frequencies, reducing noise and enabling glitch-less transitions between modes, thus optimizing power and performance based on use cases without significant current consumption impact.
Implementation Method 1
a crystal resonator (110) comprising a pair of terminals and being capable of oscillating at a fundamental resonance frequency and at least one overtone resonance frequency
Implementation Method 2
the suppression circuit (130) is configured to suppress oscillation of the crystal resonator (110) at the fundamental resonance frequency
Data Source
AI summary
A crystal oscillator is provided. The crystal oscillator includes a crystal resonator including a pair of terminals and being capable of oscillating at a fundamental resonance frequency and at least one overtone resonance frequency. Further, the crystal oscillator includes an inverter circuit coupled between the pair of terminals. The crystal oscillator additionally includes a suppression circuit configured to suppress oscillation of the crystal resonator at the fundamental resonance frequency. Further, the crystal oscillator includes a control circuit configured to control a switch circuit for selectively coupling the suppression circuit to the crystal resonator.