Photon Detector Preamplifier With Dynamic MOSFET Feedback
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Solution Overview
Problem
Conventional semiconductor X-ray detectors face challenges in achieving a large resistance value with a small volume while preventing amplifier saturation, especially when the number of incident photons increases per unit time.
Innovation Solution
A photon detector design incorporating a preamplifier with a first amplifier, a capacitive element, an n-type MOSFET, and a p-type MOSFET, where the resistance value of the MOSFETs adjusts dynamically with the output voltage, allowing for a small volume but high resistance, and preventing amplifier saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional resistance element with a large resistance value is used in the preamplifier, then the output signal rises securely and falls at an appropriate time constant, but the volume of the preamplifier increases
Solution Approach 1:
The patent changes the resistance parameter dynamically by using a transistor whose resistance value varies with the output voltage of the amplifier. When the output voltage is small, the transistor provides high resistance for proper signal rise and fall characteristics. When the output voltage increases, the resistance decreases automatically to prevent saturation, eliminating the need for a large fixed resistance element
Solution Approach 2:
The patent makes the resistance element dynamic rather than static by connecting the transistor in a feedback configuration where the gate voltage follows the output voltage. This dynamic resistance adjustment allows the preamplifier to adapt its characteristics based on the signal level, achieving both proper signal characteristics and compact size
2Productivity
If the number of incident photons per unit time increases, then the detection capability is improved, but the amplifier becomes saturated
Solution Approach 1:
The patent implements feedback by connecting the output of the amplifier to the gate of the transistor. This feedback mechanism automatically adjusts the transistor's resistance based on the output voltage level. When many photons incidentally cause large output voltages, the feedback reduces the resistance to prevent saturation, maintaining stable amplifier operation at high detection rates
Solution Approach 2:
The transistor's resistance parameter changes dynamically in response to the photon detection rate. At low detection rates, high resistance maintains proper signal characteristics. At high detection rates, the resistance decreases to prevent saturation, allowing the amplifier to handle varying photon fluxes without saturation
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 a photon detector with a small volume and high resistance, preventing amplifier saturation and enabling accurate photon counting and energy detection without signal loss, with improved power efficiency and flexibility in resistance adjustment.
Implementation Method 1
a semiconductor layer comprising a first region and a second region formed in an upper portion of the first region, respectively. The second region has a different doping concentration from the first region. The semiconductor layer may be a single crystal semiconductor layer or an amorphous semiconductor layer.
Data Source
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Figure 3A~3D
AI summary
The present embodiment relates to a photon detector which includes a preamplifier having a structure capable of preventing saturation of an amplifier. The preamplifier includes an amplifier, and further includes a capacitive element, an n-type MOSFET, and a p-type MOSFET disposed on a plurality of wirings electrically connecting the input end side and the output end side of the amplifier. A control electrode of the n-type MOSFET is set to a first fixed potential V1, while a control electrode of the p-type MOSFET is set to a second fixed potential V2.