Amplifier Circuit Capacitive Coupling for Radiation Detection
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Solution Overview
Problem
Existing amplifier circuits for radiation detectors face challenges in achieving good detection sensitivity while minimizing the risk of amplifier saturation, with limited dynamic range and variability in device characteristics, and high noise due to stray capacitances.
Innovation Solution
The design incorporates a capacitive coupling with multiple capacitors in series and shunt switches, allowing for selectable capacitance values and reduced stray capacitances through a stack of conductive layers in a semiconductor chip, enabling flexible gain selection and manufacturing repeatability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If amplifier gain is increased to improve detection sensitivity, then detection sensitivity is improved, but the risk of amplifier saturation increases
Solution Approach 1:
The patent implements a dynamic gain control mechanism where the amplifier gain is automatically adjusted based on the detected signal amplitude. The system switches between high gain mode for low energy radiation detection and low gain mode to prevent saturation from high energy radiation, resolving the contradiction between detection sensitivity and saturation risk
Solution Approach 2:
The patent changes the amplifier gain parameter dynamically based on radiation energy levels. By switching between different gain values (high gain for low energy, low gain for high energy), the system adapts to different measurement conditions, achieving both high detection sensitivity and prevention of amplifier saturation
2Device complexity
If a single fixed capacitor value is used, then the circuit is simple, but the dynamic range is limited
Solution Approach 1:
The patent replaces the fixed capacitor with a dynamic capacitance selection mechanism that switches between multiple capacitor values based on the radiation energy level. This allows the circuit to adapt its time constant and gain characteristics, achieving a wide dynamic range while maintaining reasonable circuit complexity through systematic design
Solution Approach 2:
The patent segments the capacitance function into multiple discrete capacitor values that can be selectively switched. By dividing the capacitance range into segments (different capacitor values) and switching between them, the system achieves extended dynamic range coverage while keeping each individual capacitor simple and manageable
3Ease of manufacture
If traditional capacitor implementation is used, then manufacturing is simple, but stray capacitances increase noise
Solution Approach 1:
The patent implements a nested capacitor structure where one capacitor is physically enclosed within another capacitor's structure. This nested configuration allows the stray capacitances of individual capacitors to cancel each other out, significantly reducing noise while maintaining ease of manufacture through integrated circuit fabrication techniques
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
This approach enhances detection sensitivity, reduces the risk of amplifier saturation, and achieves a wide dynamic range with low noise and consistent device characteristics, while maintaining a sturdy and reliable semiconductor chip structure.
Implementation Method 1
A capacitive coupling is coupled between the input and output of the amplifier. The electric charge that the incoming radiation causes to accumulate in the detector essentially charges the capacitor, so that a voltage signal appears at the output
Data Source
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AI summary
An amplifier circuit for a radiation detector comprises an input node (401) for receiving a charge signal from said radiation detector and an amplifier (402). The input of the amplifier (402) is coupled to said input node (401) . An output node (403) is coupled to the output of the amplifier (402). A capacitive coupling (404, 504, 604, 804, 904, 1304, 1404) is coupled between the input and output of the amplifier (402). A reset switch (405) is coupled across said capacitive coupling (404, 504, 604, 804, 904, 1304, 1404). The capacitive coupling (404, 504, 604, 804, 904, 1304, 1404) comprises at least two capacitors (406, 407, 501, 502, 801, 802, 803, 1301, 1302, 1306, 1307, 1401) coupled in series and a shunt switch (408, 503, 601, 805, 806, 901, 1303, 1305). The shunt switch (408, 503, 601, 805, 806, 901, 1303, 1305) is coupled across a respective one of said at least two capacitors (406, 407, 501, 502, 801, 802, 803, 1301, 1302, 1306, 1307, 1401).