Digitally Reconfigurable Internal Oscillator With Precision RC Tuning
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Solution Overview
Problem
Internal oscillators struggle to achieve high precision frequency due to limitations in trimming on-chip components, such as resistors or capacitors, which restrict their accuracy to around 0.5%, and require external components or complex trimming processes, making it impractical to achieve 0.1% precision.
Innovation Solution
A Frequency Tuning Module (FTM) uses a precision analog RC module with a digitally controllable clock division ratio to adjust the frequency of an internal oscillator, allowing for precise tuning by programming the number of clock periods for charging or discharging a capacitor, thereby achieving 0.1% accuracy without physical trimming of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical trimming methods (laser burning or switches) are used to adjust component values, then frequency precision can be improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent replaces physical/mechanical trimming methods (laser burning, switch adjustments) with a digital control system. A digitally controllable oscillator uses digital signals to adjust frequency parameters, eliminating the need for complex physical trimming operations while achieving high precision frequency control through software or digital logic.
Solution Approach 2:
The patent changes the approach from physically altering component values to digitally adjusting oscillator parameters. By using digital control to modify frequency parameters directly, the system achieves precise frequency tuning without requiring physical component trimming, thus reducing manufacturing complexity.
2Measurement precision
If on-chip components (resistors, capacitors) are trimmed to high accuracy, then oscillator precision can be improved, but the trimming process becomes impractical and costly
Solution Approach 1:
The patent replaces the impractical physical trimming of on-chip components with a digital control system. The digitally controllable oscillator adjusts frequency through digital parameter modification rather than physical component alteration, making manufacturing practical and cost-effective while maintaining high precision.
Solution Approach 2:
The patent creates a digital model or representation of the frequency control process, where digital parameters replicate the effect of physical component values. This digital copy allows for precise frequency adjustment without requiring actual physical trimming of on-chip components.
3Measurement precision
If an oscillator is tuned to one frequency with high precision, then frequency accuracy is improved, but the ability to retune to other frequencies with similar accuracy is reduced
Solution Approach 1:
The patent makes the oscillator dynamically adjustable through digital control. The digitally controllable oscillator can change its operating parameters on demand, allowing it to be retuned to different frequencies with high precision by simply updating digital control signals rather than requiring physical re-trimming.
Solution Approach 2:
The patent creates a universal frequency control system that can operate at multiple frequencies with high precision. The digital control mechanism provides multi-functionality, allowing the same oscillator to be accurately tuned to any required frequency within its operating range, unlike fixed-frequency oscillators that require separate trimming for each frequency.
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 approach enables flexible, digitally reconfigurable oscillators with high precision frequency tuning, reducing errors and process variations, and allows multiple oscillators on a chip to be tuned to various frequencies with unprecedented accuracy, while being simple and cost-effective.
Implementation Method 1
an RC delay element, which comprises a resistor, a capacitor and a comparator
Data Source
AI summary
A system, method and apparatus for tuning an internal oscillator to a desired frequency F1 is shown and uses an RC delay element that comprises a resistor, a capacitor and a comparator. The method includes receiving a clock signal from an oscillator to be tuned, triggering charging of the RC delay element, and N clock cycles after triggering the charging, the method determines whether the charge on the precision RC delay element is higher than or lower than a reference voltage. Correction to the clock frequency is based on the results.