Internal Oscillator Synchronization Using External Reference Feedback
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Solution Overview
Problem
Integrated circuit internal clock oscillators face challenges in maintaining long-term frequency accuracy across varying operating temperatures and voltages, leading to potential deviations in clock frequency calibration.
Innovation Solution
An internal integrated circuit clock oscillator is automatically synchronized to an external frequency reference by counting its periods within a reference period, comparing the counts, and adjusting its frequency accordingly through a frequency adjustment controller and oscillator tuning circuit to maintain precise frequency calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the internal clock oscillator frequency is increased to improve timing accuracy, then the frequency calibration accuracy improves, but the frequency deviation from the reference increases
Solution Approach 1:
The patent implements a feedback mechanism where the counter compares the actual clock oscillator frequency against a reference frequency and generates control signals to adjust the oscillator frequency accordingly. The counter counts clock cycles within a reference period and uses this information to generate frequency correction signals, creating a closed-loop feedback system that maintains accurate frequency calibration.
Solution Approach 2:
The internal clock oscillator system performs its own frequency calibration automatically using the counter and control logic integrated within the same circuit. The system self-adjusts by comparing its output against the reference and correcting its own frequency deviations without requiring external calibration equipment or manual intervention.
2Stability of the object's composition
If the internal clock oscillator frequency is decreased to maintain stability, then the frequency stability improves, but the frequency calibration accuracy deteriorates
Solution Approach 1:
The patent employs dynamic frequency adjustment where the oscillator frequency can change based on operating conditions. The system dynamically adapts the clock frequency to maintain optimal calibration accuracy across varying temperatures and voltages, transitioning from a static frequency approach to a dynamically adjustable one.
Solution Approach 2:
The system changes the oscillator frequency parameter in response to measured deviations from the reference frequency. By adjusting the frequency parameter dynamically based on environmental conditions and measured performance, the system maintains calibration accuracy across different operating states.
3Adaptability or versatility
If the operating temperature and voltage are varied to adapt to different conditions, then the adaptability improves, but the frequency calibration accuracy deteriorates
Solution Approach 1:
The feedback mechanism continuously monitors the clock oscillator frequency under varying temperature and voltage conditions and generates real-time correction signals. This allows the system to adapt to different environmental conditions while maintaining frequency calibration accuracy through automatic compensation.
Solution Approach 2:
The counter and control logic act as an intermediary between the variable operating conditions and the clock oscillator. This intermediary component measures the actual frequency under different conditions and mediates the relationship by generating appropriate correction signals to maintain calibration accuracy despite environmental variations.
4Measurement precision
If a higher frequency ratio between clock oscillator and reference is used to improve calibration accuracy, then the frequency calibration accuracy improves, but the device complexity increases
Solution Approach 1:
The counter and control logic are designed to perform multiple functions: counting clock cycles, comparing with reference, generating control signals, and resetting the counter. This multi-functional design achieves high calibration accuracy without proportionally increasing device complexity, as a single integrated circuit block performs all necessary operations.
Solution Approach 2:
The patent combines the counter, control logic, and oscillator tuning into an integrated frequency synchronization system. By merging these functions into a unified circuit architecture, the system achieves high calibration accuracy while minimizing the increase in overall device complexity through functional integration.
Data Source
AI summary
An internal integrated circuit clock oscillator is automatically synchronized to an external frequency reference by counting the number of periods of the internal clock oscillator (hereinafter “count”) that occur within a period of a lower frequency external frequency reference then comparing the count to the reference count. When the reference count is greater than the count, the frequency of the internal clock oscillator is increased. When the reference count is less than the count, the frequency of the internal clock oscillator is decreased. When the reference count and the count are substantially the same, the frequency of the internal clock oscillator is not changed.