Ring Oscillator PVT Monitor for Localized CMOS Calibration
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Solution Overview
Problem
The challenge of accurately monitoring voltage, temperature, and process variations in semiconductor circuits, particularly in performance-critical regions, becomes more critical as semiconductor components shrink, leading to performance issues due to excessive heat and voltage drops.
Innovation Solution
Incorporating complementary metal oxide semiconductor (CMOS) technology-based PVT monitoring devices with a single ring oscillator that periodically applies voltage and current signals to monitor and calibrate voltage, temperature, and process parameters, using a multiplexer to select and feed signals to the oscillator, and an analyzer to determine these parameters based on oscillation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If semiconductor components are shrunk to advance manufacturing, then manufacturing precision is improved, but temperature variations and voltage drops increase causing performance issues
Solution Approach 1:
The patent divides the semiconductor die into multiple performance-critical regions, with each region having its own dedicated PVT monitoring device. This segmentation allows localized monitoring of temperature, voltage, and process parameters in each region, enabling precise detection of variations without requiring a single large monitoring system that would occupy excessive area.
Solution Approach 2:
The PVT monitoring device is integrated directly within each performance-critical region, nesting the monitoring functionality inside the regions it monitors. This nested arrangement allows the monitoring circuits to be embedded within the performance-critical regions, minimizing additional area occupation while enabling close-proximity sensing of temperature and voltage variations.
2Measurement precision
If PVT monitoring devices are placed in performance-critical regions, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs a single ring oscillator that is periodically fed different currents corresponding to different PVT parameters through a multiplexer. This universal oscillator serves multiple functions by measuring different parameters (temperature, voltage, process variations) at different time intervals, eliminating the need for separate oscillators for each parameter and thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The monitoring device uses periodic action by sequentially applying different currents to the ring oscillator at different time intervals. The multiplexer switches between different current sources corresponding to different PVT parameters in a periodic manner, allowing the single oscillator to measure multiple parameters over time. This temporal multiplexing reduces hardware complexity while maintaining accurate measurement capabilities.
3Productivity
If multiple PVT monitoring devices are integrated on a wafer, then productivity is improved, but area occupation increases
Solution Approach 1:
The patent segments the monitoring function by placing compact PVT monitoring devices at multiple performance-critical regions across the wafer. Each monitoring device is self-contained and occupies minimal area, yet collectively they provide comprehensive coverage of the entire wafer surface, enabling high productivity through distributed monitoring without requiring a single large centralized monitoring system.
Solution Approach 2:
The monitoring circuits are nested within the performance-critical regions themselves, utilizing the existing region boundaries and structures. This nesting approach allows the monitoring devices to share space with the performance-critical circuits, minimizing additional area occupation while maximizing monitoring coverage across the wafer.
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 enables precise monitoring of voltage, temperature, and process variations with high accuracy, reducing performance issues in performance-critical circuits by detecting deviations early and allowing for proactive adjustments.
Implementation Method 1
a ring oscillator that receives the selected current and oscillates at a frequency based on the received current
Data Source
AI summary
A device includes a circuit that generates a first current associated with a voltage of a region of a semiconductor substrate, a second current associated with a temperature of the region, a third current associated with a first process parameter of the region, and a fourth current associated with a second process parameter of the region. A multiplexer of the device receives the first, second, third, and fourth currents and selects the currents one by one and periodically. A ring oscillator of the device is coupled to the multiplexer and receives the first, second, third, and fourth currents one by one and periodically, from the multiplexer. The ring oscillator oscillates at oscillation frequencies that are based on the received current from the multiplexer. The voltage, temperature, and the first and second process parameters of the region are determined based on the oscillation frequencies.