Current Measurement Circuit Using Charge Integration Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current measurement circuits face challenges in precision due to less well-defined electronic components, particularly in applications like active matrix displays where thin film transistors have undefined characteristics, affecting the accuracy of current measurement.
Innovation Solution
A current measurement circuit comprising a charge integrating circuit, a comparator circuit, and a logic circuit that integrates charge from the current to be measured, compares it with a threshold voltage, and generates a feedback signal to adjust the measurement, allowing for a pulse output that represents the current level, which is then converted to digital data, thereby being less dependent on the characteristics of the comparator and capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current measurement circuits using precise electronic components are used, then measurement precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent implements a feedback mechanism where the output of the comparator circuit is fed back to the charge integrating circuit. This feedback loop allows the circuit to automatically adjust and compensate for variations in component characteristics, achieving accurate current measurement without requiring precise electronic components. The feedback signal modifies the integration process to cancel out errors introduced by imprecise components.
Solution Approach 2:
The circuit performs self-calibration through the feedback mechanism, where the system uses its own output to correct its own measurements. The charge integrating circuit and comparator circuit work together to automatically compensate for component variations, making the measurement system self-regulating and independent of external precision calibration.
2Ease of manufacture
If thin film transistors with undefined characteristics are used, then ease of manufacture is improved, but measurement precision deteriorates
Solution Approach 1:
The feedback mechanism compensates for the undefined characteristics of thin film transistors by continuously adjusting the measurement process. The comparator circuit compares the integrated charge against a reference and generates feedback signals that correct for transistor variability, enabling accurate measurements despite using easily manufactured thin film components.
Solution Approach 2:
The patent changes the operating parameters of the measurement circuit to be independent of transistor characteristics. By using the feedback mechanism to dynamically adjust the integration process, the system transforms the measurement from being sensitive to transistor parameters into being determined by stable reference values and feedback-controlled adjustments.
3Device complexity
If the output signal depends on threshold voltage of offset voltage of comparator, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The feedback signal from the comparator output is fed back to the charge integrating circuit to compensate for threshold voltage and offset voltage variations. This feedback loop ensures that the measurement precision is maintained even though the circuit remains relatively simple, as the feedback mechanism automatically corrects for comparator imperfections.
Solution Approach 2:
The charge integrating circuit acts as an intermediary between the current input and the comparator circuit. It conditions the signal before it reaches the comparator, and the feedback from the comparator modifies this integration process, creating a mediated measurement system that achieves precision without requiring complex comparator-based circuits.
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 provides a precise current measurement that is tolerant of variations in transistor characteristics, enabling accurate current measurement even with less precise components, and is particularly effective in active matrix displays where thin film transistors are used.
Implementation Method 1
a charge integrating circuit; wherein the charge integrating circuit is arranged to integrate charge from the current to be measured and apply a resulting change in voltage as an input to the comparator circuit
Implementation Method 2
the comparator circuit is arranged to compare the input voltage with a threshold voltage level and provide an output responsive thereto to the logic circuit
Implementation Method 3
the charge integrating circuit is further arranged to integrate charge from the received feedback signal in opposition to the integrating of the charge from the current to be measured
Data Source
AI summary
Apparatus (1) and corresponding method for measuring a current (10) in which a charge integrating circuit (2) integrates charge from the current to be measured (10) and applies a resulting change in voltage to a comparator circuit (4) that compares the input voltage (12) with a threshold voltage level (Vthreshoid) and provides an output (14) responsive thereto to a logic circuit (6) that generates a feedback signal (16) dependent upon the comparator output (14) and provides the feedback signal (16) to the charge integrating circuit (2) that integrates charge from the received feedback signal (16) in opposition to the integrating of the charge from the current to be measured (10). The logic circuit (6) generates an output signal (18), based upon the comparator circuit output (14) and dependent upon the level of the current to be measured (10), for example a pulse (50) of a width (TOUT) dependent upon the level of the current (10). A converter circuit (8) may convert the output signal (18) to digital output data (20).