Load Transistor Circuit with Dynamic Regulating for Offset Errors
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Solution Overview
Problem
Existing circuit arrangements for measuring load current face challenges due to voltage offsets in measuring amplifiers, particularly affecting accuracy at small load currents, leading to inaccuracies in setting the operating point of the measuring transistor.
Innovation Solution
A circuit arrangement that includes a load transistor, a measuring transistor, a regulating circuit with a controllable resistor, a current mirror circuit, and a deactivation circuit, which adjusts the operating point of the measuring transistor based on electrical potentials and deactivates the regulating circuit when the measurement current falls below a threshold, minimizing the impact of voltage offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a regulating circuit with a measuring amplifier is used to set the operating point of the measuring transistor, then the measurement accuracy is improved, but voltage offsets in the amplifier cause measurement errors particularly at small load currents
Solution Approach 1:
The patent applies dynamics by making the regulating circuit switchable between active and inactive states based on the load current magnitude. The circuit dynamically adjusts its operation mode: for large load currents, the regulating circuit is active to ensure accurate measurement; for small load currents, the regulating circuit is deactivated to avoid offset errors. This dynamic adaptation resolves the contradiction by optimizing measurement reliability across different current ranges.
Solution Approach 2:
The patent changes the operational parameter of the regulating circuit (active/inactive state) based on the load current level. By monitoring the load current and switching the regulating circuit's state accordingly, the system adapts to different measurement conditions. This parameter change approach allows the system to avoid amplifier offset errors at small currents while maintaining measurement accuracy at larger currents.
2Measurement precision
If the regulating circuit is continuously active to maintain operating point proportionality, then measurement accuracy is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic action by switching the regulating circuit on and off based on the load current magnitude. Instead of continuous operation, the circuit is activated only when needed (for large load currents) and deactivated when not needed (for small load currents). This periodic activation pattern reduces overall power consumption while maintaining measurement accuracy during the periods when the circuit is active.
Solution Approach 2:
The patent changes the operational state parameter of the regulating circuit from continuous to conditional based on load current levels. By monitoring the current parameter and adjusting the circuit's operational state accordingly, the system achieves a balance between measurement accuracy and power consumption, activating the circuit only when high accuracy is required.
3Ease of operation
If the measuring amplifier is used to detect potential differences, then operating point setting is improved, but voltage offsets adversely influence the measurement particularly at small currents
Solution Approach 1:
The patent extracts the problematic measuring amplifier from the signal path for small load currents by deactivating it when the current is below a threshold level. This extraction eliminates the source of offset errors from the measurement chain during small current operation, allowing the system to avoid the amplifier's detrimental effects while maintaining ease of operation for larger currents where the amplifier functions properly.
Solution Approach 2:
The patent introduces a current detection mechanism as an intermediary that monitors load current levels and controls the activation state of the measuring amplifier. This intermediary element mediates between the ease of operation provided by the amplifier and the measurement precision required, switching the amplifier's state based on current levels to optimize both aspects.
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 ensures accurate measurement of load current by maintaining the operating point proportionality between the load and measuring transistors, reducing errors caused by voltage offsets, especially at small load currents, and minimizing power loss.
Implementation Method 1
a current mirror circuit (6) coupled between the first and the second measurement current path
Data Source
AI summary
One aspect is a circuit arrangement having a load current path with a load transistor having a first and a second load path terminal and a control terminal. A first measurement current path includes a measuring transistor having a first and a second load path terminal and a control terminal. The control terminals and first load path terminals of the load transistor and the measuring transistor are coupled. A first regulating circuit has a controllable resistor and is designed to drive the resistor depending on electrical potentials at the second load path terminals of the load transistor and of the measuring transistor. A current mirror circuit is coupled between the first measurement current path and a second measurement current path. A deactivation circuit is designed to deactivate the first regulating circuit depending on a current flowing through the measuring transistor.