FGMOSFET Radiation Sensor Eliminates Control Gate
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Solution Overview
Problem
Conventional FGMOSFET radiation sensors require high bias voltage, thick gate oxide, and custom CMOS processes, and lack wireless real-time read-out capabilities, making them unsuitable for miniaturization and biomedical applications where low power, low voltage operation and wireless connectivity are essential.
Innovation Solution
A FGMOSFET radiation sensor design that eliminates the control gate, uses a substrate charge injector for pre-charging, and integrates a matched FGMOSFET pair with a reference FGMOSFET for temperature compensation, allowing for low voltage operation and wireless real-time read-out using a single polysilicon CMOS process, and includes a wireless transmitter circuit for data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FGMOSFET radiation sensors use thick gate oxide and custom CMOS process, then radiation sensitivity is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the fundamental operating parameters by eliminating the control gate entirely and using a substrate charge injector instead. This allows the device to achieve radiation sensitivity without requiring thick gate oxide or custom CMOS processes, resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The control gate is extracted/removed from the FGMOSFET structure. By taking out the control gate, the patent simplifies the device structure while maintaining or improving radiation sensitivity through the substrate charge injector mechanism, directly addressing the contradiction between sensitivity and complexity
2Reliability
If conventional FGMOSFET sensors require high bias voltage operation, then radiation detection capability is maintained, but power consumption increases
Solution Approach 1:
The patent changes the voltage operation parameters by enabling low voltage operation. The substrate charge injector mechanism allows the device to function at low bias voltages while maintaining radiation detection capability, thus resolving the contradiction between reliability and power consumption
3Device complexity
If conventional FGMOSFET sensors lack wireless read-out capability, then device simplicity is maintained, but adaptability for biomedical applications decreases
Solution Approach 1:
The patent integrates multiple functions into the device by combining the radiation sensor with wireless read-out capability and temperature compensation. This makes the device adaptable for biomedical applications while maintaining reasonable simplicity through integrated design
4Measurement precision
If FGMOSFET sensors use matched pairs with temperature compensation, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the temperature compensation function with the radiation sensing function by using a matched pair of FGMOSFETs where one serves as sensor and the other as reference. This combined approach improves measurement accuracy while keeping the overall device complexity manageable through functional integration
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 design achieves improved sensitivity and reduced capacitance, enabling low-power, miniaturized radiation sensors that can be fabricated in standard CMOS technology, integrated with signal processing circuitry, and operated wirelessly, facilitating real-time dose monitoring without wired connections.
Implementation Method 1
a substrate charge injector for pre-charging
Implementation Method 2
IGFETs (insulated gate field effect transistors) may be used as sensors for detection of radiation by detecting a shift in threshold voltage (Vth) or other operating parameter after irradiation
Implementation Method 3
a matched FGMOSFET pair with a reference FGMOSFET for temperature compensation
Data Source
AI summary
A miniaturized floating gate (FG) MOSFET radiation sensor system is disclosed, The sensor preferably comprises a matched pair of sensor and reference FGMOSFETs wherein the sensor FGMOSFET has a larger area floating gate with an extension over a field oxide layer, for accumulation of charge and increased sensitivity. Elimination of a conventional control gate and injector gate reduces capacitance, and increases sensitivity, and allows for fabrication using standard low cost CMOS technology. A sensor system may be provided with integrated signal processing electronics, for monitoring a change in differential channel current ID, indicative of radiation dose, and an integrated negative bias generator for automatic pre-charging from a low voltage power source. Optionally, the system may be coupled to a wireless transmitter. A compact wireless sensor System on Package solution is presented, suitable for dosimetry for radiotherapy or other biomedical applications.