Current Amplifier Feedback Path for Wide-Range Low-Noise Measurement
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Solution Overview
Problem
Existing current amplifiers face challenges in efficiently switching between measuring small and large currents without requiring additional components at the sensitive input node, leading to circuit difficulties and noise issues.
Innovation Solution
An amplifier device with a first current path for small currents and a second current path for larger currents, utilizing protective elements like diodes in the feedback path, allowing seamless switching without additional components at the input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-impedance resistor is used for measuring small currents, then current noise is reduced, but voltage drop becomes too large for measuring larger currents
Solution Approach 1:
The patent implements dynamic switching between different current paths based on the magnitude of the input current. A switching mechanism selectively connects either the high-impedance resistor path (for small currents below 10 pA) or the low-impedance resistor path (for larger currents above 10 pA), allowing the circuit to adapt its impedance characteristics to the measurement requirements.
Solution Approach 2:
The measurement circuit is divided into two separate current paths with different impedance characteristics. The first path uses a high-impedance resistor optimized for small current measurements, while the second path uses a low-impedance resistor optimized for larger current measurements. This segmentation allows each path to be optimized for its specific current range without compromise.
2Adaptability or versatility
If additional components are added for range switching, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent makes the switching mechanism serve dual functions: it acts as a range switch to select between different current paths for measuring different current magnitudes, and simultaneously serves as the input stage for the transimpedance amplifier. This multi-functionality eliminates the need for separate switching components that would otherwise be required in conventional designs.
Solution Approach 2:
The switching mechanism and the input amplifier stage are merged into a single integrated component. Instead of having separate switches and separate amplifier inputs, the patent combines these functions so that the same component performs both the switching operation and the initial amplification, thereby reducing the total number of components.
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
Enables stable measurement across a wide dynamic range without additional components at the input, reducing noise and maintaining sensitivity for small currents.
Implementation Method 1
At least one of the protective elements of the first amplifier is included in the second current path
Data Source
AI summary
An amplifier device for receiving currents, comprising a first current path for measuring smaller currents of less than 100 pA, an input amplifier device included in the first current path, having at least one first amplifier, an output, an inverting input, a first feedback path connecting the output to the inverting input, and a feedback element included in the first feedback path, wherein the first amplifier has at least one protective element, a second current path for measuring larger currents with a maximum current of at least 10 times the current to be received in the first current path, characterized in that at least one of the protective elements of the amplifier is part of the second current path.