Photodiode self-test

Patent metadata

Field	Value
Publication number	US-8975907-B2
Application number	US-201213362027-A
Country	US
Kind code	B2
Filing date	Jan 31, 2012
Priority date	Jun 25, 2007
Publication date	Mar 10, 2015
Grant date	Mar 10, 2015

Abstract

A photodetector array includes a plurality of photodetector cells such as avalanche photodiodes and readout circuits. An array self-tester tests a dark count or other performance characteristic of the cells. The test is performed in connection with the manufacture of the array or following the installation of the array in a detection system.

First claim

Having thus described the preferred embodiments, the invention is now claimed to be:

1. A method comprising:
using circuitry fabricated on a semiconductor substrate to measure a performance characteristic of a first subset of the cells of a silicon photomultiplier fabricated on the substrate;
repeating the step of using for a second subset of the cells, wherein the first and second subsets each include a plurality of cells; and
using the silicone photomultiplier to detect radiation indicative of positron annihilations.

2. The method of claim 1 comprising comparing, for each of the cells of the first and second subsets, the measured performance characteristic and a desired performance characteristic.

3. The method of claim 1 comprising using the measured performance characteristic to adjust an operation of a cell.

4. The method of claim 1 wherein the method comprises using the measured performance characteristic to identify faulty cells and inhibiting an operation of the identified cells.

5. The method of claim 1 comprising storing a value in a memory fabricated on the substrate and using the stored value to evaluate the measured performance characteristic of a cell.

6. The method of claim 1 comprising:
receiving a first input indicative of a first performance characteristic value;
using circuitry fabricated on the substrate to evaluate the measured performance characteristic of a cell in relation to the first performance characteristic value;
receiving a second input indicative of a second performance characteristic value;
using circuitry fabricated on the substrate to evaluate the measured performance characteristic of the cell in relation to the second performance characteristic value.

7. The method of claim 1 wherein the silicon photomultiplier forms part of a system that operates according to a plurality of operating protocols and the method comprises:
determining an operating protocol of the system;
establishing a test parameter as a function of the determined protocol;
using the test parameter and the measured performance characteristic of a cell to test the cell.

8. The method of claim 1 wherein the performance characteristic of a cell varies as function of a time varying environmental condition and the method comprises:
determining a value of the time varying environmental condition;
establishing a test parameter as a function of the determined value;
using the test parameter and the measured performance characteristic to test the cell.

9. The method of claim 1 wherein the performance characteristic comprises a dark count rate.

10. The method of claim 1 wherein cells of the array are arranged in rows and columns, the first subset includes a first row, the second subset includes a second row, and using includes concurrently testing cells located in each of a plurality of columns, and repeating includes repeating the step of using for the second row.

11. The method of claim 1 including using the measured performance characteristic to identify faulty cells and determining the number of identified faulty cells.

12. The method of claim 1 wherein the circuitry comprises a plurality of counters or adders.

13. The method of claim 1 comprising repeating the step of using and the step of repeating a plurality of times.

14. The method of claim 1 comprising performing the steps of using and repeating as a part of the manufacture of the silicon photomultiplier and using a result of a test performed by the first test circuit to reject or grade the silicon photomultiplier.

15. The method of claim 1 comprising performing the steps of using and repeating following the installation of the silicon photomultiplier in an imaging system.

16. The method of claim 15 wherein the imaging system comprises a first silicon photomultiplier fabricated on a first semiconductor substrate and a second silicon photomultiplier fabricated on a second semiconductor substrate, and the method comprises concurrently performing the steps of using and performing for the first and second silicon photomultipliers.

17. The method of claim 1 comprising using the measured performance characteristic to enable an operation of a plurality of cells and generating image data indicative of radiation detected by the enabled cells.

18. A method comprising:
using circuitry fabricated on a semiconductor substrate to measure a performance characteristic of a first subset of the cells of a silicon photomultiplier fabricated on the substrate, wherein the first subset includes a first row;
repeating the step of using for a second subset of the cells, wherein the second subset includes a second row, and the first and second subsets each include a plurality of cells,
wherein using includes concurrently testing cells located in each of a plurality of columns and repeating includes repeating the step of using for the second row.

19. A method comprising:
using circuitry fabricated on a semiconductor substrate to measure a performance characteristic of a first subset of the cells of a silicon photomultiplier fabricated on the substrate;
repeating the step of using for a second subset of the cells, wherein the first and second subsets each include a plurality of cells,
wherein the steps of using and repeating are performed as a part of the manufacture of the silicon photomultiplier; and
using a result of a test performed by the first test circuit to reject or grade the silicon photomultiplier.

20. A method comprising:
using circuitry fabricated on a semiconductor substrate to measure a performance characteristic of a first subset of the cells of a silicon photomultiplier fabricated on the substrate;
repeating the step of using for a second subset of the cells, wherein the first and second subsets each include a plurality of cells;
using the measured performance characteristic to enable an operation of a plurality of cells, and
generating image data indicative of radiation detected by the enabled cells.

Assignees

• Prescher Gordian
• Frach Thomas
• Koninkl Philips Nv

Inventors

• Prescher Gordian
• Frach Thomas

Classifications

• G01R31/2635 Primary

  Testing light-emitting diodes, laser diodes or photodiodes · CPC title

• G01T1/248

  Silicon photomultipliers [SiPM], e.g. an avalanche photodiode [APD] array on a common Si substrate · CPC title

• H04N25/773

  comprising photon counting circuits, e.g. single photon detection [SPD] or single photon avalanche diodes [SPAD] · CPC title