Iowa LED system for CMS HCAL

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Iowa LED system for CMS HCAL

• By M. Miller
• Y. Onel
• University of Iowa, Iowa City, IA
• CMS Meeting, CERN
• December 1-8, 2001

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Pulser Characteristics

• Pulser located at LED
• Pulser operates from 5.5 Volts and ground
• Output pulse of 5.5 Volts
• Circuit utilizes all bipolar devices
• Rise and fall times less than 6 nanoseconds
• Electrical pulse duration from 10 nanoseconds to
  1 microsecond
• Circuit may be easily modified to drive multiple
  LEDs to achieve greater optical signal
• Signal amplitude is adjusted by varying LED
  cathode potential

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Dual Pulser Circuit Card

• Mounting of Circuit Card a.    Card is mounted
  against metal plate to increase strengthb.
  Existing 8-32 machine screw mounting is
  insufficient to support card
• Potentiometer voltage adjustment is being used in
  place of analog to digital converter for testing
  purposes
• Digital pulse input is two Lemo connectors rather
  than edge connector
• Filtered output for reverse biasing the pin
  diodes _at_ 5 VDC is provided
• Complete list of edge connector pins has not been
  provided, but 5 VDC and ground are connected
• Circuit is being mounted as specified in
  newcalibramodule drawing

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Photodiode Pulse Area vs. LED Voltage
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Dual Pulser Card with Filtered Output for PIN
Diode
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Pulser in Calibration Unit
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Pulser in Calibration Unit
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Waveform of Pulser Output
Waveform of Pulser Output (green trace) and
Photodiode Signal (Blue trace)Pulse Amplitude is
5.2 Volts.
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Pulser Cards