Switched Voltage Clamp for X-ray Detector Amplifier Offset
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
X-ray detectors face challenges in distinguishing small signal levels due to significant temperature-induced drift and noise, particularly when using high-gain amplifiers, which complicates the reliable detection of pulsed x-ray sources.
Innovation Solution
A switched voltage clamp is introduced between the x-ray detector amplifier and the analog-to-digital converter, utilizing a control circuit to synchronize the clamp with the pulsed x-ray source and reduce DC-offsets, thereby stabilizing the signal processing chain and accommodating high-gain amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-gain amplifiers are used to detect small signal levels, then detection sensitivity is improved, but output offset and drift increase significantly
Solution Approach 1:
The patent applies periodic action by using a switched voltage clamp that operates in synchronized pulses with the x-ray source. The clamp is activated periodically during the x-ray pulse to remove DC offset, then deactivated to allow signal integration, creating a rhythmic correction cycle that maintains detection sensitivity while controlling drift.
Solution Approach 2:
The voltage clamp acts as an intermediary element between the high-gain amplifier and the integrator. It mediates the conflicting requirements by introducing a controlled voltage correction that compensates for offset and drift caused by the high-gain amplifier, allowing small signal detection without being overwhelmed by offset errors.
2Measurement precision
If DC-offset removal is implemented continuously, then signal accuracy is improved, but noise from the switching mechanism increases
Solution Approach 1:
Instead of continuous DC-offset removal, the patent uses periodic action by synchronizing the voltage clamp switching with the pulsed x-ray source. The clamp operates only during the brief x-ray pulse duration, providing offset correction when needed while remaining inactive during integration periods, thereby minimizing switching noise generation.
Solution Approach 2:
The voltage clamp performs preliminary action by removing DC offset at the beginning of each x-ray pulse before the signal integration begins. This preliminary correction ensures accurate signal measurement without requiring continuous switching, thereby reducing noise while maintaining precision.
3Stability of the object's composition
If temperature compensation is increased to counteract photodiode resistance variations, then measurement stability is improved, but circuit complexity increases
Solution Approach 1:
The voltage clamp serves as an intermediary that compensates for temperature-induced variations in photodiode resistance without requiring complex temperature sensing or compensation circuits. By providing controlled voltage correction, it stabilizes the measurement against resistance variations caused by temperature changes.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the clamp voltage level in response to varying photodiode resistance caused by temperature changes. The control circuit monitors the actual resistance and modifies the compensation voltage accordingly, maintaining measurement stability without adding complex temperature control mechanisms.
Data Source
AI summary
An x-ray detector amplifier operably couples to an analog-to-digital converter interface and a switched voltage clamp is operably disposed there between. By one approach, the switched voltage clamp comprises a switched electrical connection to a constant potential (such as, but not limited to, ground). These teachings will accommodate a control circuit configured to control the switched voltage clamp. This can comprise, for example, controlling the switched voltage clamp in synchronicity with the pulsed x-ray source. These teachings will also accommodate an integrator operably connected between the x-ray detector amplifier and the analog-to-digital converter interface. In such a case, the switched voltage clamp and be controlled to remove substantially any voltage offset contribution of the x-ray detector amplifier (due, for example, to significant temperature excursions) to a signal that is integrated by the aforementioned integrator.