TMOS Radiation Sensor Circuit with Differential Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current radiation sensing devices face challenges in achieving high sensitivity and reducing self-heating effects while maintaining low power consumption, particularly in uncooled IR sensing applications using TMOS transistors.
Innovation Solution
A radiation sensing device configuration incorporating two thermally isolated TMOS transistors, a current source, voltage gate terminal, RHP zero cancelling branches, active loads, and a common mode feedback amplifier, operating the TMOS transistors at sub-threshold levels to enhance signal-to-noise ratio and temperature sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the TMOS transistor operates at higher current levels to improve signal strength, then the detection signal magnitude increases, but self-heating effects increase and temperature sensitivity deteriorates
Solution Approach 1:
The patent employs periodic modulation of the gate voltage to dynamically control the TMOS transistor operation. By switching between different gate voltage states, the system achieves periodic modulation of the detection signal while maintaining average power at low levels, thus improving signal detectability without excessive self-heating
Solution Approach 2:
The patent implements a feedback mechanism where the drain current is monitored and used to dynamically adjust the gate voltage. This feedback loop optimizes the operating point in real-time, maximizing the detection signal while compensating for temperature effects and minimizing self-heating through adaptive control
2Stability of the object's composition
If the holding arm length is increased to reduce thermal conductance, then thermal isolation improves, but interconnect resistance increases
Solution Approach 1:
The patent changes the material parameters of the interconnect by using silicided poly-silicon with optimized doping concentrations and silicide layer thicknesses. This allows achieving lower resistance in the holding arm interconnects without compromising the thermal isolation provided by the extended holding arm structure
Solution Approach 2:
The patent employs a composite interconnect structure combining poly-silicon and silicide layers. This composite material approach provides both low electrical resistance and compatibility with the thermally isolated holding arm structure, resolving the contradiction between thermal isolation and electrical conductivity
3Temperature
If the TMOS transistor is thermally isolated to improve temperature sensitivity, then uncooled operation becomes feasible, but power dissipation control becomes more difficult
Solution Approach 1:
The patent employs dynamic control of the gate voltage to adjust the TMOS transistor operating point in real-time. This dynamic operation allows the device to maintain high temperature sensitivity through thermal isolation while controlling average power dissipation by modulating the operating conditions rather than maintaining static high-power operation
Data Source
AI summary
There may be provided a radiation sensing device that includes a first TMOS with temperature dependent electrical parameters; wherein the first TMOS is exposed to radiation, and a second TMOS transistor that is sheltered from radiation. The radiation sensing device performs a differential measurement, and applied various measures for noise reduction, and maintaining the stability of the radiation sensing device.