Internal Oscillator RC Tuning for 0.1% Frequency Accuracy
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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 and capacitors, which restrict their accuracy to around 0.5%, and require external components or complex trimming processes, making it impractical to achieve 0.1% accuracy.
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 necessary for capacitor charging or discharging, thereby achieving 0.1% accuracy without physical trimming of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If physical trimming of on-chip resistors or capacitors is used, then manufacturing precision can be improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces physical/mechanical trimming of on-chip components with a digital control system. Instead of physically modifying resistors or capacitors to achieve precision, the system uses a digitally controllable oscillator with a feedback loop that measures the actual frequency and adjusts control parameters to compensate for variations, achieving 0.1% accuracy without physical trimming operations.
Solution Approach 2:
The patent introduces a feedback measurement system as an intermediary between the oscillator and the control mechanism. This intermediary measures the actual frequency output and provides information to the digital controller, which then adjusts the oscillator parameters. This intermediary layer enables precise frequency control without direct physical manipulation of the oscillator components.
2Manufacturing precision
If external precision components are used, then frequency precision can be improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent creates a multi-functional integrated circuit that combines the oscillator, frequency measurement, and digital control adjustment all in one chip. This universal device performs multiple functions (oscillation, measurement, and correction) without requiring external precision components, maintaining both high frequency accuracy and ease of manufacture through full integration.
3Manufacturing precision
If an oscillator is tuned to one frequency, then frequency precision is optimized, but adaptability to other frequencies deteriorates
Solution Approach 1:
The patent implements a dynamically adjustable oscillator system where the control parameters are not fixed but can be changed in real-time. The digital controller can modify the oscillator parameters based on feedback measurements, allowing the system to adapt to different target frequencies while maintaining precision. This dynamic adjustment capability enables the oscillator to be retuned to various frequencies without sacrificing accuracy.
4Manufacturing precision
If multiple oscillators are trimmed separately, then individual frequency accuracy is improved, but productivity deteriorates
Solution Approach 1:
The patent implements self-service trimming where each oscillator automatically measures its own frequency output and adjusts its own control parameters through an integrated feedback loop. This eliminates the need for external testing equipment and manual trimming operations for each oscillator, significantly improving productivity while maintaining individual frequency accuracy. The oscillators trim themselves autonomously during operation.
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 high precision frequency tuning of internal oscillators, reducing errors and non-idealities, and allows multiple oscillators on a chip to be tuned to various frequencies with unprecedented accuracy, while being simple, inexpensive, and practical.
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.