Amplifier Output Current Sensing from Switching Edge Timing
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Solution Overview
Problem
Existing amplifier circuits for measuring output current, particularly in clocked class D amplifiers, face high circuit complexity and limited flexibility, which is disadvantageous in applications like the aerospace sector where critical components like analog-to-digital converters and multiplexers are scarce.
Innovation Solution
The solution involves measuring switching edges of switching elements in the output stage of an amplifier circuit, using a capacitive element in parallel with the switching elements to minimize tolerance influences, and employing a time-to-digital converter and comparators to determine the output current without requiring critical components like analog-to-digital converters or multiplexers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shunt resistor or transformer with analog controller is used for measuring output current, then measurement can be carried out, but circuit complexity and adjustment complexity become very high
Solution Approach 1:
The patent extracts the current measurement function from traditional analog measurement circuits (shunt resistors, transformers) and implements it through digital timing measurements of switching edges. By measuring the time duration of switching edges and converting it to current values digitally, the complex analog measurement circuitry is eliminated, resolving the contradiction between measurement capability and circuit complexity.
Solution Approach 2:
The patent replaces mechanical/analog measurement components (shunt resistors, analog controllers) with digital electronic measurement methods. By using digital timers to measure switching edge durations and digitally processing these measurements to determine current, the system achieves current measurement without complex analog circuitry, resolving the technical contradiction.
2Measurement precision
If shunt resistor is selected for particular measuring range, then current measurement is possible, but flexibility is very limited because circuit has to be adapted to particular measuring ranges
Solution Approach 1:
The patent implements a dynamic, software-based measurement system where the current measurement range and scaling can be changed through programming rather than hardware modification. The digital timer and microcontroller can be configured to measure different current ranges by adjusting timing parameters and conversion factors, providing flexible adaptability across multiple measuring ranges without requiring physical circuit changes.
Solution Approach 2:
The patent enables flexible measurement range adaptation by changing software parameters (timing thresholds, conversion factors, scaling constants) rather than hardware components. The same physical circuit can measure different current ranges by modifying digital parameters, resolving the contradiction between measurement accuracy and measurement flexibility.
3Measurement precision
If analog-to-digital converter with multiplexer is used to measure current channels, then current measurement capability is improved, but circuit complexity becomes high which is disadvantageous in aerospace sector
Solution Approach 1:
The patent makes the digital timer unit universal by enabling it to measure switching edges from multiple amplifier channels through software configuration rather than requiring separate analog-to-digital converters for each channel. The same timing circuit can be programmed to measure different channels sequentially or simultaneously, providing multi-functional capability that reduces overall circuit complexity while maintaining measurement capability across multiple current channels.
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 approach reduces circuit complexity and allows for accurate measurement of output current with minimal influence from tolerance influences and supply voltage fluctuations, making it suitable for applications where component availability is limited.
Implementation Method 1
a capacitive element, in particular a capacitor, can be connected in parallel to at least one of the switching elements
Implementation Method 2
measuring the switching edges occurring during switching of the switching elements
Data Source
AI summary
An amplifier circuit includes a first and a second switching element connected in series between a first and a second voltage potential and are actuated in the amplifier mode in a clocked manner. A capacitive element is connected in parallel to at least one of the two switching elements, a measuring circuit for measuring the switching edges occurring during switching of the switching elements, and a current-determining circuit for determining the output current by means of the measured switching edges.