Dual Mode Tuning Digitally Controlled Crystal Oscillator
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Solution Overview
Problem
Existing digitally controlled crystal oscillators face challenges in efficiently compensating for frequency errors in crystal resonators due to temperature variations and aging, requiring separate chips and increasing manufacturing costs and complexity.
Innovation Solution
A dual mode tuning digitally controlled crystal oscillator that includes a crystal resonator, an oscillation circuit, a coarse mode tuning unit, and a fine mode tuning unit, with a tuning control unit that adjusts the coarse mode tuning signal based on the fine mode tuning signal to optimize frequency compensation, allowing for integrated chip implementation and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Voltage-Controlled Temperature Compensated Crystal Oscillator (VC-TCXO) is used to compensate for frequency error, then frequency accuracy is improved, but device complexity and manufacturing cost increase due to requiring a separate chip
Solution Approach 1:
The patent merges the frequency compensation function into the DCXO chip itself by integrating a compensation capacitor bank that can be controlled to adjust the oscillation frequency. This eliminates the need for a separate VC-TCXO chip while maintaining frequency accuracy compensation capability through digital control of the capacitor bank based on temperature and aging data.
Solution Approach 2:
The DCXO chip is designed to perform multiple functions: it generates the reference frequency, compensates for temperature variations, and compensates for aging effects. The integrated compensation capacitor bank serves as a universal mechanism that handles both temperature and aging compensation, making the chip self-sufficient and eliminating the need for external compensation circuits.
2Adaptability or versatility
If coarse mode tuning and fine mode tuning are implemented separately, then tuning range and tuning speed are improved, but device complexity increases
Solution Approach 1:
The patent segments the tuning function into two distinct modes: coarse mode tuning using a first capacitor bank for large frequency adjustments, and fine mode tuning using a second capacitor bank for precise frequency adjustments. This segmentation allows each capacitor bank to be optimized for its specific tuning range, achieving both wide tuning range and high tuning speed while keeping the overall structure manageable through clear functional division.
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
The dual mode tuning approach effectively compensates for frequency errors, reducing the need for separate chips and lowering manufacturing costs while maintaining precise frequency control, suitable for wireless mobile communication terminals.
Implementation Method 1
a crystal resonator that resonates at substantially a predetermined resonance frequency
Implementation Method 2
an oscillation circuit, coupled to the crystal resonator, generating an oscillation frequency based on the resonance frequency
Data Source
AI summary
A dual mode tuning digitally controlled crystal oscillator includes a crystal resonator, an oscillation circuit, a coarse mode tuning unit and a fine mode tuning unit. The crystal resonator resonates at substantially a predetermined resonance frequency. The oscillation circuit generates an oscillation frequency based on the resonance frequency to output the oscillation frequency. The coarse mode tuning unit performs a coarse mode tuning operation on the oscillation frequency in response to a coarse mode tuning signal, and the fine mode tuning unit performs a fine mode tuning operation on the oscillation frequency in response to a fine mode tuning signal, to substantially compensate for a frequency error of the crystal resonator. The coarse mode tuning control unit controls the coarse mode tuning signal to output a controlled coarse mode tuning signal to the coarse mode tuning unit, in response to the fine mode tuning signal.