Sparse Signal Readout Using Group Testing and TDC Multiplexing

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Solution Overview

Problem

Current silicon photomultiplier (SiPM) designs face challenges in achieving high spatio-temporal resolution while maintaining a high fill factor due to the trade-off between fill factor and chip area, leading to underutilization of the technology's potential, especially in low photon flux settings.

Innovation Solution

The use of time-to-digital converters (TDCs) as main readout devices combined with group testing techniques to reduce the number of TDCs required, allowing for efficient multiplexing and decoding of signals from a large number of sensors with a small number of TDCs, optimized through binary interconnection matrices and error-correcting codes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If each sensor is connected to its own dedicated TDC, then measurement precision and reliability are improved, but device complexity and overhead circuitry increase significantly

Engineering Contradiction:

Improvespatio-temporal resolutionVSAvoidoverhead circuitry

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Multiple sensors are merged into groups that share common TDC resources. The binary interconnection matrix defines which sensors connect to which TDCs, allowing multiple sensors to be read out through shared TDC channels, thereby reducing the total number of TDCs required while maintaining measurement capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The sensor array is segmented into multiple groups, with each group assigned to specific TDCs according to the binary interconnection matrix. This segmentation allows parallel processing of signals from different sensor groups through dedicated TDC subsets, reducing overall system complexity

Inventive Principle:

Principle #1Segmentation

2Device complexity

If the number of TDCs is reduced to decrease device complexity, then overhead circuitry and power consumption are reduced, but measurement precision and signal decoding capability deteriorate

Engineering Contradiction:

Improvenumber of TDCsVSAvoidsignal decoding accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system employs feedback through the binary interconnection matrix that encodes which sensors connect to which TDCs. This feedback structure allows the decoding algorithm to reconstruct the original sensor signals from the multiplexed TDC outputs, maintaining measurement precision despite reduced TDC count

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The binary interconnection matrix acts as an intermediary that systematically maps sensor outputs to TDC inputs. This intermediary structure enables efficient signal routing and provides the mathematical foundation for accurate signal reconstruction during the decoding process

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If more TDCs are used to increase measurement precision, then spatio-temporal resolution improves, but power consumption and device complexity increase

Engineering Contradiction:

Improvespatio-temporal resolutionVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by stationary object

Solution Approach 1:

Multiple sensors share common TDC resources through the binary interconnection matrix, reducing the total number of TDCs required. This merging approach directly reduces power consumption since TDCs are power-intensive components, while maintaining measurement precision through intelligent signal routing and decoding

Inventive Principle:

Principle #5Merging (Combining)

4Area of stationary object

If the fill factor is increased to improve sensor coverage, then area utilization improves, but the ability to maintain high spatio-temporal resolution deteriorates due to chip area constraints

Engineering Contradiction:

Improvefill factorVSAvoidspatio-temporal resolution

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

Sensors are merged into groups that share TDC resources, allowing more sensors to be packed into the same chip area without proportionally increasing the number of TDCs. This merging enables higher fill factor while maintaining the spatio-temporal resolution capability through efficient resource sharing

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9197805B2Digital multiplexing readout for sparse signals on imaging arrays

Publication Date: 2015.11.24 THE BOARD OF TRUSTEES OF THE LELAND STANFORD JUNIOR UNIV

AI summary

A method for providing an image from a device with a plurality of sensors and a plurality of time to digital converters (TDC) is provided. Data signals are generated by some of the plurality of sensors, wherein each sensor of the plurality of sensors provides output in parallel to more than one TDC of the plurality of TDCs and wherein each TDC of the plurality of TDCs receives in parallel input from more than one sensor of the plurality of sensors and where a binary matrix indicates which sensors are connected to which TDC. The data signals are transmitted from the sensors to the TDCs. TDC signals are generated from the data signals. Group testing is used to decode the TDC signals based on the binary matrix.