ON Semiconductor
Is Now

To learn more about onsemi™, please visit our website atwww.onsemi.com

onsemi andand other names, marks, and brands are registered and/or common law trademarks of Semiconductor Components Industries, LLC dba “onsemi” or its affiliates and/orsubsidiaries in the United States and/or other countries. onsemi owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of onsemi
product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf. onsemi reserves the right to make changes at any time to any products or information herein, without
notice. The information herein is provided “as-is” and onsemi makes no warranty, representation or guarantee regarding the accuracy of the information, product features, availability, functionality,or suitability of its products for any particular purpose, nor does onsemi assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and allliability, including without limitation special, consequential or incidental damages. Buyer is responsible for its products and applications using onsemi products, including compliance with all laws,regulations and safety requirements or standards, regardless of any support or applications information provided by onsemi. “Typical” parameters which may be provided in onsemi data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application
by customer’s technical experts. onsemi does not convey any license under any of its intellectual property rights nor the rights of others. onsemi products are not designed, intended, or authorized
for use as a critical component in life support systems or any FDA Class 3 medical devices or medical devices with a same or similar classification in a foreign jurisdiction or any devices intended for
implantation in the human body. Should Buyer purchase or use onsemi products for any such unintended or unauthorized application, Buyer shall indemnify and hold onsemi and its officers, employees,
subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or deathassociated with such unintended or unauthorized use, even if such claim alleges that onsemi was negligent regarding the design or manufacture of the part. onsemi is an Equal Opportunity/AffirmativeAction Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. Other names and brands may be claimed as the property of others.

AND9795/D
A Brief Introduction toSilicon Photomultiplier(SiPM) Sensors
The Silicon Photomultiplier (SiPM) is a low-light sensor that has
performance characteristics comparable to a conventional PMT withthe practical advantages of a solid-state sensor. The SiPM is well
suited to a variety of applications including LiDAR, medical imaging,radiation detection and biosciences.
The SiPM is operated in Geiger-mode which enables high gain
(1x106) at moderate bias (~30 V). This is achieved by creating a highfield region in the diode that generates a self-perpetuating charge
avalanche when a photon is absorbed. Once a current is flowing
through the diode, it should then be stopped or ‘quenched’. Passive
quenching (i.e. no active circuitry), is achieved through the use ofa series resistor which limits the current drawn by the diode during
breakdown. This lowers the reverse voltage seen by the diode toa value below its breakdown voltage, thus halting the avalanche. The
diode then recharges back to the bias voltage, and is available to detect
subsequent photons.
In this way, a single photodiode device operated in Geiger-mode
functions as a photon-triggered switch, in either an ‘on’ or ‘off’ state.
Proportional information on the magnitude of an instantaneous photon
flux is not available. A photodiode operated in the Geiger mode isreferred to as a SPAD (Single Photon Avalanche Diode).
The SiPM is formed of a dense array of small, independent SPAD
sensors, each with its own quenching resistor, as shown schematicallyin Figure 1. Each independently operating unit of SPAD and quench
resistor is referred to as a “microcell”. When a microcell in the SiPM
fires in response to an absorbed photon, a Geiger avalanche is initiatedcausing a photocurrent to flow through the microcell. It is important tonote that the Geiger avalanche will be confined to the single microcell
it was initiated in. During the avalanche process, all other microcells
will remain fully charged and ready to detect photons. The sum of thephotocurrents from each of these individual microcells combines toform a quasi-anlog output, and is thus capable of giving informationon the magnitude of an instantaneous photon flux. The response tolow-level light pulses is shown in Figure 2, and a charge spectrum ofthese pulses is shown in Figure 3.

www.onsemi.com

APPLICATION NOTEAnodeFastOutput

CathodeFigure 1. A SiPM Consists of an Array ofMicrocells (SPAD Plus Quench Resistor)
with Summed Output

Figure 2. SiPM Output when Illuminated by Brief Pulses of Low-level Light, Showing the Discrete Photon Levels© Semiconductor Components Industries, LLC, 2017

January, 2019 − Rev. 31

Publication Order Number:AND9795/D

AND9795/D

Figure 3. Charge Spectrum Showing the Well Defined Single and Multiple Photon Peaks

Figure 4. The Standard (Anode-cathode) and Fast Output Pulses
SIPM RESPONSE

ON Semiconductor has developed a unique modification
to the standard silicon photomultiplier structure that results
in a third terminal (in addition to the anode and cathode).
This is referred to as the fast output and is the sum of thecapacitively-coupled outputs from each microcell, asillustrated in Figure 1.

The SiPM output pulses are shown in Figure 4. Readingout from the anode or cathode is referred to as the standard
output. The recovery time of the sensor is determined by themicrocell recharge time constant. This is dependent upon thevarious capacitances and resistances in the sensor system.
Since the capacitance of the microcell will depend upon its
area, the reset time will vary for different microcell sizes.

www.onsemi.com
2

AND9795/D
The dynamic range is a function of the total number ofmicrocells, the overvoltage used, and the wavelength of theincident photons. Figure 5 shows the typical dynamic range
for 1mm, 3mm and 6mm sensors. It can be seen that thesensor has a linear response at lower photon fluxes, but as thenumber of incident photons increases, the sensor will start
to saturate.
SIPM READOUT

Please consult the Biasing and Readout Application Note
AND9782/D for guidance on the usage of SiPM sensors.
FURTHER INFORMATION

For a more in-depth introduction to the silicon
photomultiplier including the various performanceparameters, please see our Introduction to the Silicon
Photomultiplier (SiPM) Application Note, AND9770/D.

Figure 5. The SiPM Photocurrent as a Function ofIncident Power on a Log-log Scale

SensL is a registered trademark of Semiconductor Components Industries, LLC (SCILLC) or its subsidiaries in the United States and/or other countries.
ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries.
ON Semiconductor owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of ON Semiconductor’s product/patent
coverage may be accessed at www.onsemi.com/site/pdf/Patent−Marking.pdf. ON Semiconductor reserves the right to make changes without further notice to any products herein.
ON Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does ON Semiconductor assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.
Buyer is responsible for its products and applications using ON Semiconductor products, including compliance with all laws, regulations and safety requirements or standards,
regardless of any support or applications information provided by ON Semiconductor. “Typical” parameters which may be provided in ON Semiconductor data sheets and/or
specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer
application by customer’s technical experts. ON Semiconductor does not convey any license under its patent rights nor the rights of others. ON Semiconductor products are notdesigned, intended, or authorized for use as a critical component in life support systems or any FDA Class 3 medical devices or medical devices with a same or similar classification
in a foreign jurisdiction or any devices intended for implantation in the human body. Should Buyer purchase or use ON Semiconductor products for any such unintended or unauthorized
application, Buyer shall indemnify and hold ON Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, andexpenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if suchclaim alleges that ON Semiconductor was negligent regarding the design or manufacture of the part. ON Semiconductor is an Equal Opportunity/Affirmative Action Employer. Thisliterature is subject to all applicable copyright laws and is not for resale in any manner.

PUBLICATION ORDERING INFORMATION
LITERATURE FULFILLMENT: Literature Distribution Center forON Semiconductor 19521 E. 32nd Pkwy, Aurora, Colorado
80011 USA Phone: 303−675−2175 or 800−344−3860 Toll Free
USA/Canada Fax: 303−675−2176 or 800−344−3867 Toll Free
USA/Canada Email: orderlit@onsemi.com◊N. American Technical Support: 800−282−9855 Toll Free
USA/CanadaEurope, Middle East and Africa Technical Support:
Phone: 421 33 790 2910

www.onsemi.com
3

ON Semiconductor Website: www.onsemi.com
Order Literature: http://www.onsemi.com/orderlit
For additional information, please contact your loca
Sales Representative

AND9795/D