DC Decoupled Current Measurement Circuit for High Potential Loads
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Solution Overview
Problem
Current current measurement circuits for power transistors, especially at high DC potentials, require complex designs and large chip areas due to the need for high-voltage components, which complicates circuit design and increases power consumption, especially when measuring negative source potentials.
Innovation Solution
A circuit arrangement using a sense transistor coupled to a load transistor with a floating sense circuit and a DC decoupling capacitor to transfer the sense current to a non-floating measurement circuit, allowing for efficient current measurement at high DC potentials without the need for extensive high-voltage components, by using electronically controllable switches and capacitors to manage source potential differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high voltage circuit components are used to measure current at high DC potentials, then measurement capability at high DC potentials is achieved, but circuit design complexity increases and chip area increases
Solution Approach 1:
The measurement circuit is divided into two separate parts: a floating sense circuit that operates at high DC potentials and a non-floating measurement circuit that operates at ground potential. These two circuits are connected through a DC decoupling capacitor, allowing the high voltage measurement function to be segmented from the low voltage processing function, thereby reducing the complexity of individual components while maintaining overall measurement capability.
Solution Approach 2:
A DC decoupling capacitor is introduced as an intermediary element between the floating sense circuit and the non-floating measurement circuit. This capacitor couples the high voltage floating potential to the ground-referenced measurement circuit, enabling signal transfer without requiring high voltage proof components in the measurement path, thus simplifying the circuit design.
2Measurement precision
If high voltage circuit components are used to measure current at high DC potentials, then measurement capability at high DC potentials is achieved, but chip area increases
Solution Approach 1:
The measurement circuit is divided into two separate parts: a floating sense circuit that operates at high DC potentials and a non-floating measurement circuit that operates at ground potential. These two circuits are connected through a DC decoupling capacitor, allowing the high voltage measurement function to be segmented from the low voltage processing function, thereby reducing the complexity of individual components while maintaining overall measurement capability.
Solution Approach 2:
A DC decoupling capacitor is introduced as an intermediary element between the floating sense circuit and the non-floating measurement circuit. This capacitor couples the high voltage floating potential to the ground-referenced measurement circuit, enabling signal transfer without requiring high voltage proof components in the measurement path, thus simplifying the circuit design.
3Measurement precision
If high voltage proof components are used for digital output measurement, then measurement capability is achieved, but circuit design problems increase
Solution Approach 1:
The measurement circuit is divided into two separate parts: a floating sense circuit that operates at high DC potentials and a non-floating measurement circuit that operates at ground potential. These two circuits are connected through a DC decoupling capacitor, allowing the high voltage measurement function to be segmented from the low voltage processing function, thereby reducing the complexity of individual components while maintaining overall measurement capability.
Solution Approach 2:
A DC decoupling capacitor is introduced as an intermediary element between the floating sense circuit and the non-floating measurement circuit. This capacitor couples the high voltage floating potential to the ground-referenced measurement circuit, enabling signal transfer without requiring high voltage proof components in the measurement path, thus simplifying the circuit design.
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 efficient current measurement at high DC potentials with reduced chip area and power consumption, maintaining proportionality between load and sense currents across varying source potentials, including negative values, and allows for digital output without the need for high-voltage proof components except for the decoupling capacitor.
Implementation Method 1
A non-floating measurement circuit is coupled to the sense circuit via a DC decoupling capacitor for transferring the floating signal representing the sense current to the non-floating measurement circuit
Data Source
AI summary
A circuit arrangement for measuring a load current provided to a load via a first load terminal of a load transistor is disclosed. In accordance with one example of the invention, the circuit arrangement includes a sense transistor coupled to the load transistor to provide a sense current representing the load current at a first load terminal of the sense transistor. The first load terminals of the load and the sense transistors are at respective floating electric potentials. A floating sense circuit coupled between the load terminals of sense transistor and load transistor, at least in one mode of operation the sense circuit receives the sense current and provides a floating signal representing the sense current. A non-floating measurement circuit is coupled to the sense circuit via a DC decoupling capacitor for transferring the floating signal representing the sense current to the non-floating measurement circuit. The measurement circuit is configured to provide an output signal representing the floating signal and thus the sense current.