Alternating Low Pass Filter Current Measurement Circuit
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Solution Overview
Problem
Existing current measurement technologies face challenges in achieving high sensitivity and low noise, particularly in applications like nanopore sensing and medical X-ray detectors, due to the need for multiple amplifiers and increased power consumption.
Innovation Solution
A current measuring apparatus is designed with a first charge amplifier, a processing circuit with alternating low pass filter modules, and a second charge amplifier, which reduces the number of amplifiers needed by alternating sampling between two low pass filter modules, thereby minimizing power consumption and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple amplifiers are used to achieve high sensitivity current measurements, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The signal processing function is divided into two stages: a first charge amplifier performs initial signal integration, and a second charge amplifier processes the filtered output. This segmentation allows each amplifier to operate more efficiently, reducing the total power consumption while maintaining measurement precision.
Solution Approach 2:
The patent implements alternating sampling between two low pass filter modules, where one filter is active while the other is reset or in standby. This periodic action reduces the average power consumption of the filtering stage while maintaining effective noise suppression throughout the measurement cycle.
2Measurement precision
If multiple amplifiers are used to achieve high sensitivity current measurements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Each charge amplifier is designed to perform multiple functions: signal integration, noise filtering (through the alternating low pass filters), and output conditioning. This multi-functionality reduces the need for separate dedicated components, thereby reducing overall device complexity while maintaining high measurement precision.
3Measurement precision
If continuous noise filtering is applied to suppress noise, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The low pass filtering is implemented in an alternating manner between two filter modules across successive sensing frames. One filter processes signals while the other is reset or in standby mode. This periodic operation maintains effective continuous noise suppression while reducing the average power consumption compared to having both filters continuously active.
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 proposed solution achieves reduced noise levels and power consumption while maintaining effective noise suppression, making it suitable for high-sensitivity current measurements in applications like nanopore sensing and medical X-ray detectors.
Implementation Method 1
a first charge amplifier configured to integrate a current to be measured
Implementation Method 2
a processing circuit configured to filter an output from the first charge amplifier using a first low pass filter module and a second low pass filter module
Implementation Method 3
a second charge amplifier configured to integrate a current derived from the filtered output from the first charge amplifier
Data Source
AI summary
Methods and apparatus for measuring current are provided. In one arrangement, a first charge amplifier integrates a current to be measured. A processing circuit filters an output from the first charge amplifier using a first low pass filter module and a second low pass filter module. A second charge amplifier integrates a current derived from the filtered output from the first charge amplifier. The apparatus is configured to reset the first charge amplifier at the start of each of a plurality of sensing frames. The processing circuit obtains at least a first sample of the output from the first charge amplifier in each sensing frame. The sampling of the first sample alternates from one sensing frame to the next sensing frame between sampling via the first low pass filter module and sampling via the second low pass filter module.