Bipolar Shaper Circuit for Depth Measurement in Radiation Sensors
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Solution Overview
Problem
High-Z semiconductor radiation sensors face limitations due to poor charge transport properties, charge trapping, and challenges in accurately measuring the depth of interaction of ionizing events, leading to degraded spectral resolution and signal-to-noise ratio.
Innovation Solution
A readout unit is developed that generates a bipolar shaped cathode signal to determine the depth of interaction by measuring the time between specific peaks of the signal, using charge amplification and timing shaping to improve the accuracy of depth measurement without requiring multiple samples or high digital activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional filtering and threshold measurement methods are used for cathode signal timing, then signal-to-noise performance is improved, but timing measurement accuracy degrades due to amplitude dependence and error accumulation
Solution Approach 1:
The patent replaces conventional electronic filtering and threshold-based timing methods with a bipolar shaper circuit that directly processes the cathode signal. The bipolar shaper transforms the unipolar cathode signal into a bipolar waveform where the zero-crossing point provides amplitude-independent timing information, eliminating the need for complex filtering and multiple measurements while improving both signal-to-noise ratio and timing accuracy
Solution Approach 2:
The patent changes the waveform parameter from unipolar to bipolar by using a bipolar shaper circuit. This parameter transformation allows the timing measurement to be based on the zero-crossing point of the bipolar signal rather than threshold crossings of the unipolar signal, making the timing measurement independent of signal amplitude and reducing error accumulation
2Measurement precision
If multiple sampling and extrapolation methods are used for cathode signal timing, then timing resolution is improved, but device complexity and digital activity increase
Solution Approach 1:
The patent replaces complex multiple sampling and extrapolation systems with a simple bipolar shaper circuit followed by a single zero-crossing detector. This substitution maintains high timing resolution while dramatically reducing device complexity and digital activity by using analog signal processing instead of multiple digital samples and computations
3Object-affected harmful factors
If unipolar shaping is used for cathode signal, then signal-to-noise ratio is improved, but timing measurement becomes amplitude-dependent
Solution Approach 1:
The patent changes the signal parameter from unipolar to bipolar by using a bipolar shaper circuit. This transformation creates a waveform where the zero-crossing point occurs at a consistent time regardless of signal amplitude, eliminating the amplitude dependence problem while maintaining the signal-to-noise ratio improvement through proper shaping
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 the spectral resolution and signal-to-noise ratio by directly measuring the depth of interaction with improved timing resolution, reducing errors associated with charge trapping and poor charge transport properties.
Implementation Method 1
electrical signals that are converted into voltages by charge amplifiers electrically coupled to the cathode and anode
Implementation Method 2
generate a bipolar shaped cathode signal based on the cathode signal. The bipolar shaped signal can have a first pulse corresponding to a first change in slope of the cathode signal and a second pulse corresponding to a second change in slope of the cathode signal
Implementation Method 3
determine an amount of time between a peak of the first pulse and a peak of the second pulse, the amount of time represents the depth of interaction
Data Source
AI summary
The preferred embodiments of the present invention include a device for measuring an ionizing event in a radiation sensor. The device can include a charge amplifier and a timing shaper. The charge amplifier receives a cathode signal and is configured to output an amplified cathode signal. The timing shaper is operatively connected to the charge amplifier to receive the amplified cathode signal. The timing shaper is configured to generate a first pulse in response to a beginning of the ionizing event and a second pulse in response to an end of the ionizing event. The first and second pulses are associated with a depth of interaction of the ionizing event and are generated in response to a slope of the amplified cathode signal changing.