Current Detection Circuit With Dynamic Capacitor Gain Switching
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Solution Overview
Problem
Current spectrometer detection circuits face challenges in accurately and efficiently detecting currents over a large dynamic range, particularly in miniaturized and portable devices, due to noise and saturation issues, which limits their ability to detect ion currents as low as 10 femto-ampere and requires long waiting periods for accurate measurements.
Innovation Solution
A high-speed and low-noise current detection device utilizing an integrating circuit with a network of capacitors for gain setting, an analog-to-digital converter, and a processor to convert current to a voltage ramp, analyze the slope, and reconfigure the capacitors to adjust integration time and gain settings, thereby improving detection speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current detection circuits are used in spectrometers, then the device can measure spectral components, but it cannot accurately detect currents over a large dynamic range due to noise and saturation issues
Solution Approach 1:
The patent implements dynamic gain adjustment by reconfiguring the capacitor network in the integrating circuit based on the detected current magnitude. When the current exceeds the detectable range, the system automatically switches capacitor configurations to adjust the gain, enabling accurate measurement across a wide dynamic range from 10 fA to 100 nA without saturation or noise interference
Solution Approach 2:
The system changes the integration time constant by reconfiguring the capacitor network (changing capacitance values) to adapt to different current magnitudes. This parameter adjustment allows the detection circuit to maintain optimal sensitivity across varying current levels, resolving the contradiction between measurement precision and dynamic range adaptability
2Measurement precision
If traditional detection circuits are used, then the spectrometer can operate, but it requires long waiting periods for accurate measurements
Solution Approach 1:
The system performs preliminary detection to assess the current magnitude and predicts whether the signal will be out-of-range. Based on this preliminary assessment, it proactively adjusts the capacitor configuration and integration parameters before the main measurement, eliminating the need for long waiting periods while maintaining measurement accuracy
Solution Approach 2:
The system continuously monitors the voltage ramp signal and uses feedback to determine if the current is out-of-range. Based on this feedback, it automatically reconfigures the capacitor network and adjusts integration time, enabling rapid adaptation without requiring extended waiting periods for accurate measurements
3Measurement precision
If the integration time is increased to improve detection accuracy for low currents, then the detection precision improves, but the detection speed decreases
Solution Approach 1:
The system dynamically adjusts the integration time constant by reconfiguring the capacitor network based on the detected current magnitude. For low currents (10 fA range), it uses longer integration times with appropriate capacitor configurations to maximize accuracy, while for higher currents it uses shorter integration times, thereby maintaining both high detection accuracy and fast detection speed across the full dynamic range
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
The solution enables the detection of currents across a wide dynamic range with improved speed and accuracy, reducing noise interference and saturation issues, allowing for detection of ion currents as low as 10 pico-ampere within a shorter time, and enhancing the overall performance of spectrometers.
Implementation Method 1
an integrating circuit including a network of capacitors for providing a gain setting and configured to convert the current to a voltage ramp over a length of integration time
Data Source
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AI summary
A device (400) of detecting a current (405) from a sensor (490) is disclosed. The device comprising: an integrating circuit (435) including a network of capacitors (430) for providing a gain setting and configured to convert the current to a voltage ramp over a length of integration time, the integrating circuit further including a reset switch (420) configured to connect an input and an output of the network of capacitors; an ADC (440) configured to digitize the voltage ramp into a plurality of voltage samples; and a set of modules (480) including an analyzing module (482) configured to analyze the plurality of voltage samples to determine a slope of the voltage ramp; an outputting module (488) configured to determine a magnitude of the current based on the slope of the voltage ramp and the gain setting; and a reconfiguring module (484) that is configured to reconfigure the network of capacitors and reset the voltage ramp via the reset switch.