Bidirectional Current Sense Amplifier With Floating Supply Rails
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current current sense amplifier circuits face challenges in accurately sensing and amplifying differential voltages across sense resistors for both common mode voltages within and exceeding the supply voltage range, while maintaining precision and bi-directional current sensing capabilities.
Innovation Solution
The proposed current sense amplifier circuit employs dual-path differential amplifiers with multiple input stages powered by floating voltage supply rails referenced to a floating ground, along with a transconductance compensation circuit to ensure accurate signal translation and amplification across a wide range of common mode voltages, and includes a voltage selector circuit to manage voltage supply and ground references effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a current sense amplifier circuit uses a single supply voltage reference, then the circuit structure is simple, but it cannot accurately sense current for common mode voltages exceeding the supply voltage range
Solution Approach 1:
The voltage supply structure is segmented into multiple independent floating voltage supply rails (first floating voltage supply rail, second floating voltage supply rail, third floating voltage supply rail, fourth floating voltage supply rail), each referenced to a common floating ground rail. This segmentation allows each rail to be independently adjusted to match different common mode voltage levels, enabling accurate sensing across extended voltage ranges while maintaining a structured supply architecture.
2Measurement precision
If the amplifier path directly amplifies the differential input voltage, then the amplification is straightforward, but offset voltages and noise reduce measurement precision
Solution Approach 1:
The amplifier functionality is segmented into two separate paths: a null amplifier path and a main amplifier path. The null amplifier path processes the differential input voltage to generate a null output voltage that compensates for offset voltages and noise. The main amplifier path then amplifies the differential input voltage using this null output as a reference. This segmentation enables high measurement precision by separating the offset compensation function from the signal amplification function.
3Measurement precision
If floating voltage supply rails are used for each input stage, then accurate sensing across wide voltage ranges is achieved, but the voltage supply management becomes complex
Solution Approach 1:
All floating voltage supply rails (first, second, third, and fourth floating voltage supply rails) are referenced to a common floating ground rail, establishing an equipotential reference framework. This equipotentiality ensures that voltage differences are maintained correctly across all amplifier stages regardless of the absolute voltage levels, simplifying the management of floating supplies while maintaining sensing accuracy across wide common mode voltage ranges.
Data Source
AI summary
In a general aspect, a current sense amplifier circuit (CSA) can include a null amplifier path and a main amplifier path that are both configured to receive a differential input voltage. The null amplifier path can output a first differential output voltage based on the differential input voltage. The main amplifier path can also be configured to receive the first differential output voltage and output a second differential output voltage based on the differential input voltage and the first differential output voltage. The null and main amplifier paths can each include a differential amplifier having first and second input stages that are each configured to receive the differential input voltage. The first input stage and the second input stage of the main amplifier path can and be powered by a respective (first and second) floating voltage supply rails that are referenced to a floating ground rail.