Frequency Dependent Impedance Circuit for SSPM Pulse Shaping
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Solution Overview
Problem
Conventional readout pulse shaping from solid state photomultipliers (SSPMs) using front end buffer amplifiers results in a signal with slow rise time and slow fall time, which can attenuate the pulse and degrade the signal-to-noise ratio when used in nuclear detectors.
Innovation Solution
A frequency dependent input impedance circuit is employed between the SSPM and the buffer amplifier to shape the readout pulse, providing greater impedance during the discharge portion and lower impedance during the recharge portion, using components like inductors and capacitors to ensure equivalent discharge and recharge times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional front end buffer amplifier is used to readout the SSPM signal, then the circuit is simple and easy to implement, but the readout pulse has slow rise time and slow fall time which attenuates the pulse and degrades the signal-to-noise ratio
Solution Approach 1:
A frequency dependent input impedance circuit is introduced as an intermediary component between the SSPM and the buffer amplifier. This circuit acts as a mediator that shapes the readout pulse by providing frequency-dependent impedance, thereby improving the signal-to-noise ratio without requiring a complete redesign of the buffer amplifier stage.
Solution Approach 2:
The input impedance circuit changes its impedance parameter dynamically based on frequency. During the discharge portion (higher frequency), it provides greater impedance to enhance the pulse signal, while during the recharge portion (lower frequency), it provides lower impedance to reduce the long tail effect, thus optimizing the signal-to-noise ratio across different pulse phases.
2Measurement precision
If a frequency dependent input impedance circuit is added to shape the readout pulse, then the signal-to-noise ratio is improved, but the device complexity increases
Solution Approach 1:
The frequency dependent input impedance circuit serves as an intermediary stage that can be added to existing SSPM readout systems without replacing the core buffer amplifier or SSPM components. This modular approach allows for signal-to-noise ratio improvement while maintaining relative simplicity in the overall system architecture.
3Measurement precision
If the impedance circuit provides greater impedance during discharge portion, then the pulse signal is enhanced, but the recharge time may be extended
Solution Approach 1:
The input impedance circuit dynamically changes its impedance parameter based on the frequency content of the signal. During the discharge portion with higher frequency content, it provides greater impedance to enhance the pulse signal. During the recharge portion with lower frequency content, it automatically provides lower impedance to minimize the extension of recharge time, thus balancing signal enhancement with time duration control.
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 effectively reduces the long tail of the recharge portion of the readout pulse, maintaining the discharge portion's integrity and improving the signal-to-noise ratio by compensating for the slow decay associated with conventional SSPM readout configurations.
Implementation Method 1
A frequency dependent input impedance circuit can be employed to shape a readout pulse from a solid state photomultiplier
Data Source
AI summary
Exemplary embodiments are directed to shaping a readout pulse from a solid state photomultiplier (SSPM). A readout pulse can be received from the SSPM at an input of a buffer amplifier. The readout pulse can have a discharge portion with a discharge rate and a recharge portion with a recharge rate. A magnitude of the readout pulse increasing for the discharge portion and decreasing for the recharge portion. A frequency dependent input impedance circuit can be employed in electrical communication with the input of the buffer amplifier to shape the discharge portion of the readout pulse.