Cell Potential Readout Circuit for Low-Frequency Signal Detection
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Solution Overview
Problem
Conventional cell potential measuring devices using a single feedback auto-zero differential amplifier cannot detect signals in frequency bands lower than the cutoff frequency based on the reset period of the sampling capacitor, leading to deteriorated measurement accuracy, particularly for synaptic potentials in biological solutions.
Innovation Solution
Incorporating a high resistance element in parallel with a capacitor and connecting a second capacitor between the reference electrode and the input terminal of the differential amplifier, allowing for improved frequency response and reducing the need for periodic reset operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a sampling capacitor is used with periodic reset operation to prevent leakage current effects, then stability of the differential amplifier operating point is improved, but measurement precision deteriorates due to inability to detect low-frequency signals below the cutoff frequency
Solution Approach 1:
The patent divides the single sampling capacitor into two separate capacitors: a first sampling capacitor connected to the read electrode for capturing signal information, and a second sampling capacitor connected to the reference electrode for stabilizing the operating point. This segmentation allows each capacitor to perform its specific function independently, eliminating the need for periodic reset operations that would affect low-frequency signal detection while maintaining operating point stability.
Solution Approach 2:
The patent introduces a differential amplifier as an intermediary component between the sampling capacitors and the output. The differential amplifier processes the signals from both capacitors, allowing the system to maintain stable operating points through one capacitor while preserving low-frequency signal information from the other capacitor, thus resolving the contradiction between stability and measurement precision.
2Reliability
If periodic reset operation is performed on the sampling capacitor, then reliability is improved by preventing potential fluctuation due to leakage current, but productivity deteriorates due to loss of low-frequency signal information
Solution Approach 1:
By segmenting the sampling function into two separate capacitors, the system can continuously sample signals without periodic reset operations. The first capacitor captures low-frequency signals continuously, while the second capacitor provides stable reference sampling, eliminating the need for reset operations that would interrupt low-frequency signal detection and improve productivity.
Solution Approach 2:
The patent enables continuous sampling action by removing the periodic reset requirement. The dual-capacitor configuration allows both capacitors to continuously hold their respective sampled values without needing periodic refreshing, ensuring uninterrupted detection of low-frequency signals and maintaining continuous useful measurement action.
Data Source
AI summary
The present disclosure relates to a semiconductor device and a cell potential measuring device capable of improving measurement accuracy of a potential of a solution. A semiconductor device includes a read electrode that reads a potential of a solution, a differential amplifier, a first capacitor connected in series in a loop feeding back an output of the differential amplifier to a second input different from a first input from the read electrode, a resistance element connected in parallel with the first capacitor, and a second capacitor connected between a reference electrode indicating a reference potential and the second input. The present disclosure can be applied to, for example, a cell potential measuring device.