On-Chip Current Sensing Circuit With Shared ADC for Low-Voltage ICs
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Solution Overview
Problem
Current integrated circuit (IC) designs that measure load currents consume substantial substrate area and power due to multiple transducers and analog-to-digital converters (ADCs), which is problematic for portable devices powered by batteries.
Innovation Solution
The IC design incorporates a single transducer and ADC with a multiplexer to manage multiple current sensing circuits, reducing area and power consumption while maintaining accurate control over subcircuits and power switches through complex control systems processing multibit digital signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple transducers and ADCs are used for current sensing in each subcircuit, then current measurement accuracy is improved, but substrate area consumption increases
Solution Approach 1:
Multiple current sensing circuits share a single transducer and ADC by time-multiplexing the measurement process. The multiplexer sequentially connects different sensing circuits to the shared transducer and ADC, allowing accurate current measurement across multiple subcircuits while using minimal substrate area.
Solution Approach 2:
A single transducer and ADC are designed to serve multiple current sensing functions by being sequentially allocated to different sensing circuits through the multiplexer. This multi-functional approach allows one component to replace what would traditionally require multiple dedicated components, reducing overall substrate area.
2Measurement precision
If multiple transducers and ADCs are used for current sensing in each subcircuit, then current measurement accuracy is improved, but power consumption increases
Solution Approach 1:
Multiple current sensing circuits share a single transducer and ADC by time-multiplexing the measurement process. The multiplexer sequentially connects different sensing circuits to the shared transducer and ADC, allowing accurate current measurement across multiple subcircuits while using minimal substrate area.
Solution Approach 2:
The current measurement process operates periodically, with the multiplexer sequentially switching between different sensing circuits at predetermined time intervals. This periodic time-multiplexing allows the single transducer and ADC to measure currents from multiple subcircuits over time, maintaining measurement accuracy while significantly reducing power consumption compared to having always-active dedicated converters.
3Area of stationary object
If a single transducer and ADC are shared among multiple sensing circuits, then substrate area and power consumption are reduced, but device complexity increases
Solution Approach 1:
A multiplexer is introduced as an intermediary component that manages the time-shared connection between multiple sensing circuits and the single transducer/ADC. The multiplexer receives control signals from the control system and automatically routes the appropriate sensing circuit to the transducer, simplifying the overall control logic while enabling area-efficient sharing.
Data Source
AI summary
An on-chip low-voltage current sensing circuit for measuring current in an integrated circuit (IC). In one embodiment, an IC formed on a substrate, which includes a plurality of subcircuits, and a plurality of sensing circuits coupled to the plurality of subcircuits, respectively. The plurality of sensing circuits are configured to generate a plurality of currents, respectively, that are proportional to a plurality of load currents, respectively, consumed by the plurality of subcircuits, respectively, during operation thereof. A circuit is coupled to the plurality of sensing circuits and configured to generate a signal based on an aggregate of the plurality of currents.