BioFET Logarithmic Current-to-Time Converter for Wide Dynamic Range
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Solution Overview
Problem
BioFETs operated in the subthreshold region produce nonlinear output signals, leading to narrow input dynamic ranges, which are not effectively addressed by linear transimpedance amplifiers or digital compensation methods, requiring complex designs and increased chip area.
Innovation Solution
Employing a logarithmic current-to-time converter to convert exponential current signals from bioFETs into linear time domain signals, eliminating the need for analog-to-digital converters and simplifying the readout system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear transimpedance amplifiers or digital compensation methods are used to address nonlinear output signals from bioFETs, then measurement precision may be improved, but device complexity and chip area increase significantly
Solution Approach 1:
The patent changes the operating parameters of the bioFET by applying a specific gate voltage to operate the device in a region where the output current has a linear relationship with the analyte concentration. This parameter adjustment eliminates the need for complex compensation circuits while maintaining measurement precision.
Solution Approach 2:
The patent extracts and eliminates the nonlinear transformation step from the readout system. By directly measuring the output current without requiring transimpedance amplification or digital compensation, the system removes complex components while preserving the ability to accurately detect analyte concentrations.
2Adaptability or versatility
If complex compensation methods are employed to widen input dynamic range, then adaptability improves, but manufacturing precision requirements and chip area increase
Solution Approach 1:
The patent adjusts the gate voltage parameter to operate the bioFET in a linear region, which inherently provides a wide input dynamic range without requiring complex compensation circuits. This simplifies manufacturing requirements while maintaining adaptability across different analyte concentrations.
3Measurement precision
If traditional readout systems with multiple compensation circuits are used, then measurement accuracy may be maintained, but power consumption and device complexity increase
Solution Approach 1:
The patent removes power-consuming compensation circuits and transimpedance amplifiers from the readout system. By operating the bioFET in a linear region and directly measuring the output current, the system maintains detection accuracy while significantly reducing power consumption.
Solution Approach 2:
The bioFET operates autonomously in a linear region without requiring external compensation circuits. The device self-regulates its output characteristics through proper gate voltage biasing, eliminating the need for additional power-consuming 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
The solution provides a low-cost, low-power biosensor system with a wide input dynamic range, enabling efficient and accurate detection of biological and chemical analytes without the complexity of traditional compensation methods.
Implementation Method 1
a bioFET configured to receive to a first voltage signal and output a current signal
Implementation Method 2
a logarithmic current-to-time converter connected to the bioFET and is configured to receive the current signal and convert the current signal to a time domain signal, the time domain signal varying logarithmically with respect to the current signal
Data Source
AI summary
A bio-field effect transistor (bioFET) system includes a bioFET configured to receive to a first voltage signal and output a current signal, where the current signal varies exponentially with respect to the first voltage signal. A logarithmic current-to-time converter is connected to the bioFET and is configured to receive the current signal and convert the current signal to a time domain signal. The time domain signal varies logarithmically with respect to the current signal, such that the time domain signal varies linearly with respect to the first voltage signal.