Ring Oscillator Current Sensing for Distributed Power Gating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrated circuits (ICs) face challenges in effectively managing power consumption, as excessive load currents can lead to damage or malfunction, and existing current sensing methods are not adequately equipped to handle distributed load currents across multiple cores efficiently.
Innovation Solution
The apparatus and method involve a power gating circuit with current sensors using ring oscillators and frequency-to-code converters to generate digital signals indicative of load currents, allowing a controller to manage and reduce harmful currents, thereby preventing damage or malfunction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current sensing circuit is used to monitor load current, then IC damage or malfunction is prevented, but the device complexity increases
Solution Approach 1:
The patent replaces traditional voltage-based current sensing with a ring oscillator-based sensing mechanism. The ring oscillator's oscillation frequency varies with supply voltage, which in turn reflects load current levels. This substitution transforms the sensing approach from direct electrical measurement to a frequency-based indirect measurement, reducing the need for complex sensing circuits while maintaining reliability
Solution Approach 2:
The patent changes the sensing parameter from direct voltage or current measurement to frequency measurement. By monitoring the oscillation frequency of the ring oscillator, which changes with supply voltage and thus with load current, the system achieves current sensing through a different physical parameter. This parameter change simplifies the sensing circuitry while preserving the ability to detect harmful current levels
2Adaptability or versatility
If traditional current sensing methods are used, then single-point current monitoring is achieved, but distributed load currents across multiple cores cannot be effectively monitored
Solution Approach 1:
The patent divides the current sensing function into multiple independent ring oscillators, each associated with specific cores or circuit blocks. Each ring oscillator monitors the load current of its associated cores independently. This segmentation allows distributed monitoring across multiple cores while maintaining measurement precision for each segment, as each oscillator provides accurate local current information
Solution Approach 2:
The ring oscillator serves multiple functions: it acts as both a clock source for the associated cores and a current sensing element. The same oscillating circuit that provides timing signals also generates frequency variations that reflect load current levels. This multi-functionality enables distributed monitoring without adding separate dedicated sensing circuits, maintaining measurement precision while achieving versatility
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
This solution enables precise monitoring and control of load currents across multiple cores, effectively preventing damage and ensuring stable operation by generating digital signals that reflect voltage differences, allowing for timely intervention by the controller.
Implementation Method 1
a first ring oscillator including: a first set of one or more inverters coupled to a first node between the power gating circuit and the first circuit, and a second set of one or more inverters coupled to a second node between the power gating circuit and the second circuit
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Apparatus for sensing distributed load currents provided by power gating circuit. The apparatus includes a power gating circuit including a set of bulk transistors coupled in series with a set of circuits between first and second voltage rails. The apparatus includes a current sensor with a first ring oscillator, a first frequency-to-code (FTC) converter, a second ring oscillator, a second FTC converter, and a subtractor. The first ring oscillator includes a first set of one or more inverters configured to receive a first voltage at a node between the power gating circuit and the first circuit, and a second set of one or more inverters configured to receive a second voltage at a second node between the power gating circuit and the second circuit. The first ring oscillator is configured to generate a signal including a frequency related to the voltage drops across the first and second sets of transistors.