On-Die DC-DC Converter Current Mirror Sensing for Per-Phase Power
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Solution Overview
Problem
In integrated circuits (ICs), accurately measuring power distribution across on-die DC-DC converters is challenging due to the difficulty in sensing driver currents without dissipating power, especially in multi-phase buck DC-DC converters where current measurement is essential for per-phase current limiting and preventing overheating.
Innovation Solution
A current sensing circuit is implemented that generates a mirror current proportional to the driver current, using a high side driver (HSD) and low side driver (LSD) circuit configuration, with a current mirror circuit and amplifier circuit to sense the driver current indirectly, allowing for accurate measurement of the driver current without dissipating power, and an over-current detection circuit to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct current sensing is used to measure driver current, then measurement precision is improved, but power dissipation increases
Solution Approach 1:
The patent uses an intermediary approach by sensing the voltage across the inductor rather than directly sensing the driver current. This voltage sensing method acts as an intermediary that provides current measurement information without the power dissipation associated with direct current sensing paths, thereby resolving the contradiction between measurement precision and power loss
Solution Approach 2:
The patent replaces direct electrical current sensing (which would dissipate power through sense resistors) with voltage sensing across the inductor. This substitution uses the inductor's inherent voltage during switching operations to derive current information, eliminating the need for additional power-dissipating sensing components
2Productivity
If multi-phase buck DC-DC converters are used to distribute power, then power distribution efficiency is improved, but complexity of current measurement increases
Solution Approach 1:
The patent implements a universal voltage sensing approach that can be applied to each phase of the multi-phase converter using the same methodology. By sensing the voltage across each phase's inductor and processing it through identical circuitry, the system achieves accurate per-phase current measurement without requiring different measurement techniques for each phase, thus managing complexity while maintaining efficiency
Solution Approach 2:
The patent segments the current measurement function into individual phase measurements by sensing voltage across each phase's inductor separately. This segmentation allows independent monitoring of each phase's current, enabling per-phase current limiting while maintaining overall system efficiency through modular, repeatable measurement circuits
3Reliability
If per-phase current limiting is implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring the voltage across each phase inductor and using this information to regulate the driver current. The sensed voltage provides real-time feedback about the current state, allowing the control circuit to adjust switching duty cycles to prevent overcurrent conditions and overheating, thereby improving reliability through a relatively simple feedback mechanism
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 precise measurement of driver currents in on-die DC-DC converters, facilitating effective power management and preventing overheating by accurately monitoring and limiting current levels, thus improving power distribution efficiency.
Implementation Method 1
generates a mirror current proportional to the driver current, using a high side driver (HSD) and low side driver (LSD) circuit configuration, with a current mirror circuit
Data Source
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AI summary
Current sensing in an on-die direct current-direct current (DC-DC) converter for measuring delivered power is disclosed. A DC-DC converter converts input voltage to output current at an output voltage coupled to a load circuit. The DC-DC converter includes a high side driver (HSD) circuit to drive the output current in a first stage, and a low side driver (LSD) circuit to couple the power output to a negative supply rail (GND) in a second phase, output current being periodic. The DC-DC converter includes an amplifier circuit to equalize an output voltage and a mirror voltage. Based on the mirror voltage, the current sensing circuit generates mirror current that corresponds to driver current. The mirror current can be measured as a representation of the output current delivered to the load circuit. A plurality of the DC-DC converters can provide multi-phased current to the load circuit for providing power to the load circuit.