Oscillator Clock Calibration for Fast Frequency Convergence
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Solution Overview
Problem
Controllable oscillator circuits in integrated circuits face frequency drift due to environmental changes, leading to inefficiencies in achieving target frequencies, especially when transitioning from open-loop to closed-loop operation or under significant operating condition changes.
Innovation Solution
A method involving an oscillator circuit that receives a first control value based on a predetermined nominal relationship, compares the output clock signal with a reference clock signal to determine an offset, and adjusts the control value to quickly converge to the target frequency by calculating a second control value that differs significantly from the first, utilizing either a nominal or operational relationship to compensate for manufacturing and operational variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If crawling feedback is used to correct frequency drift, then circuit complexity is reduced, but convergence speed to target frequency deteriorates
Solution Approach 1:
The patent applies dynamics by making the control value adjustment adaptive rather than fixed. The controller dynamically adjusts the control value based on the measured frequency offset, allowing the system to transition from static crawling to dynamic convergence. This enables faster initial convergence while maintaining simplicity, as the adjustment magnitude is determined by actual offset measurements rather than predetermined fixed steps.
Solution Approach 2:
The patent implements feedback by measuring the actual frequency offset between the output clock signal and reference clock signal, then using this measured offset to adjust the control value. This closed-loop feedback mechanism allows the system to converge to the target frequency based on actual performance rather than relying solely on predetermined crawling steps, significantly improving convergence speed while keeping the circuit relatively simple.
2Use of energy by moving object
If crawling feedback is used to correct frequency drift, then power consumption is reduced, but time to achieve target frequency increases
Solution Approach 1:
The system dynamically adjusts the control value based on measured frequency offsets rather than using fixed incremental crawling steps. This dynamic approach allows the oscillator to converge to the target frequency much faster by making larger initial adjustments when needed, reducing the time loss while maintaining reasonable power consumption through targeted rather than continuous adjustments.
Solution Approach 2:
The patent applies preliminary action by measuring the frequency offset and calculating the appropriate control value adjustment before making the correction. This allows the system to proactively correct frequency deviations rather than reacting slowly through incremental crawling, significantly reducing the time required to achieve the target frequency while keeping power consumption manageable through selective correction.
3Device complexity
If a fixed control value adjustment is used, then circuit simplicity is maintained, but accuracy in achieving target frequency under varying conditions deteriorates
Solution Approach 1:
The patent uses feedback to measure the actual frequency offset between the output clock signal and the reference clock signal, then adjusts the control value based on this measured offset. This feedback mechanism enables the circuit to adapt to varying environmental conditions and manufacturing variations, significantly improving frequency accuracy while maintaining relative circuit simplicity through the use of standard oscillator and counter components.
Solution Approach 2:
The patent applies parameter changes by adjusting the control value based on measured frequency offsets. Rather than using a fixed control value, the system dynamically changes the control parameter (control value) according to actual frequency measurements, allowing the oscillator to maintain high accuracy under varying temperature, voltage, and manufacturing conditions while keeping the circuit design relatively simple.
Data Source
AI summary
A method is disclosed for producing an output clock signal with a target frequency using an oscillator circuit portion configured to receive a control value and produce an output clock signal with a frequency dependent on the control value. In one embodiment, the method comprises providing a first control value to the oscillator circuit portion corresponding to the target frequency, so as to cause the oscillator circuit portion to produce the output clock signal with a first frequency, comparing the output clock signal with a reference clock signal having a reference frequency to determine an offset between the first frequency and the target frequency, and providing a second control value to the oscillator circuit portion that differs from the first control value by a magnitude calculated with reference to the determined offset, to cause the oscillator circuit portion to produce the output clock signal with a second frequency.