Ring Oscillator Calibration for IR-Drop Clock Accuracy
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Solution Overview
Problem
Signal generators in digital circuits face performance degradation due to IR-drop caused by resistance in power meshes, leading to inaccurate clock frequencies.
Innovation Solution
A signal generator design incorporating a main ring oscillator and a first ring oscillator, where the first ring oscillator is used to calibrate the frequency of the output oscillation signal by selectively disabling and enabling it, and a processor performs regression analysis to calculate the correct frequency, accounting for resistance in the power mesh.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a signal generator uses a power mesh to supply voltage to the main ring oscillator, then the circuit structure is simplified and power delivery is improved, but the resistance of the power mesh causes IR-drop that degrades the clock frequency accuracy
Solution Approach 1:
The patent creates a copy of the main ring oscillator (first ring oscillator) that is identical or similar in structure and couples it to the same power mesh. This copy oscillator serves as a reference to measure the frequency degradation caused by IR-drop. By comparing the main oscillator's frequency with the copy oscillator's frequency, the system can calculate and compensate for the frequency error, thereby maintaining accurate clock frequency despite the presence of power mesh resistance.
2Measurement precision
If the first ring oscillator is enabled for frequency calibration, then the frequency accuracy is improved, but the power consumption increases due to additional oscillators operating
Solution Approach 1:
The first ring oscillator (copy oscillator) is not continuously enabled but is activated periodically or selectively for calibration purposes. The processor enables the first ring oscillator only when frequency calibration is needed, measures the frequency difference, and then disables it. This periodic activation approach allows the system to achieve frequency compensation while minimizing the additional power consumption that would result from continuous operation of the calibration oscillator.
3Measurement precision
If multiple ring oscillators are used for calibration, then the frequency compensation accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent uses a single copy (first ring oscillator) of the main ring oscillator for calibration purposes. This copy is identical or similar in structure to the main oscillator and is coupled to the same power mesh. By using just one copy rather than multiple oscillators, the system achieves effective frequency compensation while keeping the device complexity and cost manageable. The processor compares the main oscillator frequency with the single copy oscillator frequency to calculate the frequency error and apply compensation.
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
The solution effectively compensates for IR-drop-induced frequency degradation, ensuring accurate output clock frequencies with a simple and cost-effective circuit structure.
Implementation Method 1
the frequency of the output oscillation signal is decreased because of the resistance of the power mesh
Data Source
AI summary
A signal generator includes a main ring oscillator and a first ring oscillator. The main ring oscillator is supplied by a power voltage, and is configured to generate an output oscillation signal. The main ring oscillator is coupled through a power mesh to the power voltage. The first ring oscillator is supplied by the power voltage. The first ring oscillator is similar or identical to the main ring oscillator. The first ring oscillator is coupled through the power mesh to the power voltage. The first ring oscillator is used to calibrate a frequency of the output oscillation signal.