CPU Power Consumption Measurement via Current Mirroring
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Solution Overview
Problem
Existing methods for determining real-time power consumption in devices are inefficient, often requiring significant area increases and interfering with device operations, and struggle to accurately correlate software application effects due to frequency disparities and operational interference.
Innovation Solution
A system where a CPU executes a software application portion to generate a reference current matching the current through electrical circuitry, using a control word to vary the current, allowing for accurate power consumption correlation without external hardware or additional pins, utilizing transistors, amplifiers, and current digital-to-analog converters to sense and mirror currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a series element is added at the device's input power pin to measure voltage for determining power consumption, then power consumption can be measured, but the area increases significantly and the measurement interferes with the device's operation
Solution Approach 1:
The patent merges the power consumption measurement function with existing device components by having the CPU execute software application portions and use its existing computational resources to determine power consumption, rather than adding separate dedicated measurement hardware. This combines multiple functions (CPU execution, power measurement) into a single integrated system.
Solution Approach 2:
The CPU is made multi-functional by enabling it to both execute software application portions and determine power consumption based on that execution. This universal approach allows the same component to serve multiple purposes, eliminating the need for separate measurement hardware that would increase area.
2Measurement precision
If a series element is added at the device's input power pin to measure voltage, then power consumption can be measured, but the device's operation is interfered with
Solution Approach 1:
The measurement function is merged with the CPU's existing operational flow by having the CPU execute software portions and determine power consumption through computation rather than external measurement. This integration eliminates interference with device operation while maintaining measurement capability.
3Measurement precision
If the device outputs program counter samples over a trace interface to correlate software effects with power consumption, then correlation accuracy improves, but the trace interface operation interferes with the software application's operation
Solution Approach 1:
The patent extracts the correlation function from separate trace interface operations and integrates it directly into the CPU's execution flow. By having the CPU determine power consumption based on executing software application portions, the correlation is achieved without requiring separate trace interface operations that would interfere with software execution.
Solution Approach 2:
The correlation of software effects with power consumption is merged into the CPU's native execution process. The CPU simultaneously executes software and determines power consumption through the same operational flow, eliminating the need for separate trace interface operations and their associated interference.
4Device complexity
If the measurement frequency is kept slow to simplify hardware, then hardware complexity reduces, but the ability to accurately correlate power consumption with software execution is lost
Solution Approach 1:
The patent changes the fundamental parameter of measurement frequency from slow (external sampling) to fast (synchronized with CPU execution). By having the CPU determine power consumption based on executing software application portions, the measurement naturally occurs at the CPU's operational frequency, providing accurate correlation without requiring complex high-speed external hardware.
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
Enables accurate real-time power consumption determination without area increase or operational interference, allowing for efficient power profiling and debugging by correlating software application effects with minimal hardware intrusion.
Implementation Method 1
A current is generated through a transistor for mirroring the current through the electrical circuitry
Data Source
AI summary
For determining a power consumption of electrical circuitry, at least one device executes at least a portion of a software application having an effect on a current through the electrical circuitry. A current is generated through a transistor for mirroring the current through the electrical circuitry. In response to a control word, a reference current is generated. In response to executing the portion of the software application, the control word is varied to determine a value thereof that causes the reference current to approximately equal the current through the transistor, in a manner that correlates the effect of the portion of the software application on the current through the electrical circuitry.