Digital Oscillator Frequency Adjustment for Stable Precision Tuning
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Solution Overview
Problem
Existing crystal controlled oscillators face challenges in accurately setting frequency within a desired range due to limitations in resolution, stability, and noise degradation, which increases production costs and reduces efficiency, especially in applications requiring high frequency stability like GPS technology.
Innovation Solution
A frequency synthesizer with a direct digital synthesizer (DDS) and microcontroller that adjusts frequency digitally within a set variable range using gain values, allowing precise frequency setting without changing hardware configurations, thereby enhancing stability and reducing noise impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog voltage regulator is used to adjust frequency, then frequency adjustment capability is provided, but resolution of adjustment is limited and stability is poor
Solution Approach 1:
The patent replaces the analog voltage regulator system with a digital frequency synthesizer system. Instead of using analog components (voltage regulators, varicap diodes controlled by analog voltage), the invention uses digital components (microcontroller, DDS - Direct Digital Synthesis) to generate and control the output frequency. This substitution eliminates the inherent limitations of analog systems such as noise, drift, and resolution constraints, providing both high precision frequency adjustment and stable output.
2Adaptability or versatility
If two varicap diodes are used to expand frequency variable range, then frequency variable range is increased, but device complexity and production cost increase
Solution Approach 1:
The patent implements a universal digital frequency synthesizer that can provide any frequency within a wide range by programming the microcontroller and adjusting digital parameters. Instead of requiring different hardware configurations (such as multiple varicap diodes) for different frequency ranges, the single digital system can be reconfigured software-wise to serve multiple frequency requirements, thereby reducing device complexity while maintaining versatility.
3Measurement precision
If hardware configuration is customized for each frequency range, then frequency adjustment accuracy is improved, but production efficiency decreases and cost increases
Solution Approach 1:
The patent employs parameter changes in the digital domain rather than physical hardware changes. By modifying digital values stored in the microcontroller (such as frequency words in DDS), the system can accurately set different frequencies without any hardware reconfiguration. This allows a single standardized hardware design to be mass-produced efficiently, while maintaining high frequency setting accuracy through software parameter adjustment.
4Ease of operation
If variable capacitance element is used for frequency adjustment, then frequency tuning is enabled, but non-linear region limits adjustment and secular change causes frequency drift
Solution Approach 1:
The patent replaces the variable capacitance element (varicap diode) with a digital frequency synthesizer. Instead of tuning frequency by changing capacitance in an analog resonant circuit (which suffers from non-linear regions and secular changes), the invention uses digital computation to generate frequencies. This eliminates the physical limitations of capacitive tuning and provides both ease of operation and high frequency stability.
Data Source
AI summary
An oscillator includes a nominal frequency output unit, a frequency adjustment amount output unit, a gain output unit, a multiplier, and an adder. The nominal frequency output unit is configured to output a first digital value corresponding to the nominal frequency. The frequency adjustment amount output unit is configured to output a second digital value corresponding to a rate of frequency in order to set a frequency adjustment amount with respect to the nominal frequency using the rate of frequency. The gain output unit is configured to output a third digital value corresponding to a gain to be multiplied by the second digital value. The multiplier is configured to multiply the second digital value by the third digital value, thus outputting a fourth digital value. The adder adds the first digital value and the fourth digital value to output the added result as a setting signal of frequency.