APV25, Clock and Trigger
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Transcript of APV25, Clock and Trigger
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APV25, Clock and Trigger
M.Friedl
HEPHY Vienna
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2Markus Friedl (HEPHY Vienna)18 Mar 2009
APV25
• Please refer to my December 2008 meeting slides for details about APV25 (SVD session)
• In Nov/Dec 2008 beam test, we confirmed that APV works perfectly fine with both – 42.4 MHz clock (=RF/12) 3.5 µs max L1 latency– 31.8 MHz clock (=RF/16) 4.7 µs max L1 latency
• We can make the APV25 clock switchable
Schematics of one channel
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3Markus Friedl (HEPHY Vienna)18 Mar 2009
APV25 Pipeline & TriggerSimulation
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4Markus Friedl (HEPHY Vienna)18 Mar 2009
APV25 Trigger Restrictions
(1) Minimum L1 distance of 6 APV clocks– Irrelevant in case of 500ns dead time as requested
by ECL
(2) Maximum pipeline filling– also affected by such dead time requirement
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5Markus Friedl (HEPHY Vienna)18 Mar 2009
APV Trigger Simulation
• Input: CLK, L1 rate• Model: APV25 state
machine, exponential trigger distribution
• Output: FIFO filling histogram, trigger loss, Poisson distribution to check randomness of simulated triggers
Download:http://belle.hephy.at/apvtrg.zip(needs Labwindows/CVI 8.1 run-
time engine from http://ni.com)
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6Markus Friedl (HEPHY Vienna)18 Mar 2009
Results – No External Dead Time Requirement
• Min Lost: trigger restriction (1) = too little distance• FIFO Lost: trigger restriction (2) = too many pending readouts• Nakao-san wishes <3% dead time @ L1=30kHz OK (0.87%) for 42.4MHz clock, slightly higher (3.43%) at 31.8MHz
Trigger Loss @ 42.4MHz
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Trigger rate [kHz]
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loss [
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FIFO Lost [%]
Min Lost [%]
Trigger Loss @ 31.8MHz
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Trigger rate [kHz]T
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loss [
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FIFO Lost [%]
Min Lost [%]
12.8 25.9
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7Markus Friedl (HEPHY Vienna)18 Mar 2009
Trigger Loss @ 42.4MHz
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Trigger rate [kHz]
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FIFO Lost [%]
Min Lost [%]
Results – External 500 ns Dead Time Requirement
• Nakao-san‘s wish (<3% dead time @ L1=30kHz) met in both cases 0.42% for 42.4MHz clock and 2.7% at 31.8MHz• 500ns dead time (as required by ECL) not accounted for APV25
– Hence no minimum lost figure always zero
Trigger Loss @ 31.8MHz
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Trigger rate [kHz]T
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loss [
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FIFO Lost [%]
Min Lost [%]
11.4 24.0
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8Markus Friedl (HEPHY Vienna)18 Mar 2009
Summary
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9Markus Friedl (HEPHY Vienna)18 Mar 2009
Summary
• APV25 has trigger limitations due to (1) Minimum L1 distance of 6 APV clocks(2) Maximum pipeline filling
• APV25 can operate at both 42.4MHz (RF/12) or 31.8MHz (RF/16) clocks
• In case of no external limitation, we get @ 30kHZ L1:– 0.87% for 42.4MHz clock, 3.43% at 31.8MHz
(see December slides for more detail)• With 500ns dead time as requested by ECL we get
– 0.42% for 42.4MHz clock, 2.7% at 31.8MHz
– Conclusion: With 500ns ECL dead time, both frequencies are fine according to Nakao-san‘s wish of <3% APV25 dead time @ L1=30kHz