Load Current Measurement Circuit Using Transistor Differential
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electronic circuits face challenges in efficiently measuring load current in voltage regulator systems, such as low-dropout (LDO) regulators, where precise current measurement is necessary but not effectively addressed.
Innovation Solution
The electronic circuit design includes a first and second transistor coupled between the power supply node and load, with a control node and measuring circuit to measure the difference between current provided by a current source and consumed by the load, utilizing a comparator to determine the load current based on the width ratio of the transistors and a reference current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional current measurement approach is used in an LDO regulator, then the circuit structure remains simple, but the current measurement precision and efficiency are insufficient
Solution Approach 1:
The current measurement function is segmented into two parallel transistor paths: a first transistor path for load current delivery and a second transistor path for current sampling. The measuring circuit further segments the sampled current into reference current and difference current components, enabling precise measurement while maintaining functional separation and circuit modularity
Solution Approach 2:
A current source is introduced as an intermediary element that provides a controlled reference current through the second transistor. This intermediary current serves as a benchmark for comparison, enabling the measuring circuit to accurately determine the difference between reference and load currents through controlled current mirroring and subtraction
2Adaptability or versatility
If the current measurement range needs to cover both small and large currents, then the adaptability improves, but the difficulty of detecting and measuring increases
Solution Approach 1:
The circuit employs dynamically adjustable parameters including variable resistance values and controllable current source magnitudes. The measuring circuit can adapt its operating point and measurement scale based on the actual load current magnitude, enabling accurate detection across wide current ranges from microamperes to millamperes through dynamic parameter optimization
Solution Approach 2:
The circuit utilizes parameter changes in transistor width ratios, resistance values, and current source magnitudes to adapt the measurement scale. By adjusting these parameters, the same circuit topology can accurately measure different current ranges, transforming the measurement capability from fixed to variable and enabling universal applicability
Data Source
AI summary
An electronic circuit is described comprising a load, a power supply node, a first transistor coupled between the supply node and the load such that the input at a control terminal of the first transistor controls current flow from the supply node to the load through the first transistor, a current source, a second transistor coupled between the current source and the load such that the input at a control terminal of the second transistor controls current flow from the current source to the load through the second transistor, a control node coupled to the control terminal of the first transistor and the control terminal of the second transistor and a measuring circuit connected to the point of coupling between the current source and the second transistor configured to measure the difference between the current provided by the current source and the current consumed by the second transistor.