apv25, clock and trigger

APV25, Clock and Trigger

M.Friedl

HEPHY Vienna

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

3Markus Friedl (HEPHY Vienna)18 Mar 2009

APV25 Pipeline & TriggerSimulation

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

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)

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]

Tri

gg

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loss [

%]

FIFO Lost [%]

Min Lost [%]

Trigger Loss @ 31.8MHz

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Trigger rate [kHz]T

rig

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loss [

%]

FIFO Lost [%]

Min Lost [%]

12.8 25.9

7Markus Friedl (HEPHY Vienna)18 Mar 2009

Trigger Loss @ 42.4MHz

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Trigger rate [kHz]

Tri

gg

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loss [

%]

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

rig

ger

loss [

%]

FIFO Lost [%]

Min Lost [%]

11.4 24.0

8Markus Friedl (HEPHY Vienna)18 Mar 2009

Summary

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