Ring Oscillator Foldover Detection for Stable Voltage Scaling
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Solution Overview
Problem
Existing oscillators in voltage regulators face challenges in accurately detecting foldover events, which affect the optimization of power consumption and efficiency in dynamic voltage scaling, particularly in systems where the frequency of the oscillator signal decreases beyond a threshold.
Innovation Solution
The implementation of a control circuitry that includes a first and second ring oscillator, where the frequency of the oscillator signal increases up to a threshold and then decreases, generating a foldover signal by comparing the oscillating signals, and utilizing this foldover signal to adjust the supply voltage through a switching voltage regulator, thereby preventing further adjustments when the foldover occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If dynamic voltage scaling is implemented to optimize power consumption, then power efficiency is improved, but accurate detection of foldover events becomes difficult leading to instability
Solution Approach 1:
A foldover detection circuit is introduced as an intermediary component between the oscillator and the voltage regulator control logic. This circuit generates a foldover detection signal that accurately identifies when the oscillator frequency begins to decrease, allowing the system to prevent further voltage adjustments and maintain stable operation during dynamic voltage scaling.
2Productivity
If the oscillator frequency is used as feedback for switching control, then dynamic voltage scaling is achieved, but foldover events cause frequency degradation and loss of control accuracy
Solution Approach 1:
The foldover detection circuit performs preliminary detection of the foldover event before significant frequency degradation occurs. By monitoring the oscillator signal and generating a detection signal at the precise moment frequency begins to decrease, the system can take preventive action to maintain control accuracy and avoid the harmful effects of foldover.
3Adaptability or versatility
If the oscillator operates beyond the threshold voltage, then dynamic range is increased, but frequency decreases due to foldover reducing system performance
Solution Approach 1:
The foldover detection signal is fed back to the voltage regulator control logic to modify its operation. When the detection signal indicates a foldover event, the control logic adjusts its behavior to prevent further voltage changes that would exacerbate frequency degradation, thereby maintaining optimal oscillator frequency across a wider operating range.
Data Source
AI summary
Control circuitry is disclosed including an oscillator operable to generate an oscillator signal. A frequency of the oscillator signal increases as an amplitude of a first voltage increases up to a threshold, and the frequency of the oscillator signal decreases as an amplitude of the first voltage exceeds the threshold. The oscillator is operable to generate a foldover signal indicating when the frequency of the oscillator signal is decreasing due to the first voltage exceeding the threshold.