1. E. Noah, CMS Tracker Week, January 2003 APV Power Dependence on Trigger: First Observations on Hybrid Effect first observed in Strasbourg and reported by Jean-Daniel Berst. Large drop in hybrid current when the trigger is removed.  I 250 ~ 230 mA for a 6 APV module  I 250 ~ 160 mA for a 4 APV module (from 660 mA to 500 mA) Following the removal of triggers, the current decreases slowly and stabilises with a time constant of a few seconds. Normal current is sustained with trigger rates above a few Hz

2. E. Noah, CMS Tracker Week, January 2003 First Observations on a Hybrid Where does the current change occur on the hybrid? What is its dependence on trigger rate? What is its exact magnitude? How important will this effect be for CMS?

3. E. Noah, CMS Tracker Week, January 2003 Measurements on the APV25 I 125 does not vary with trigger status but I 250 does. Hint that current drop is related to the analogue bias.  Look at how the current changes with bias register settings. Breakdown of current drawn by various sub-circuits, per channel

4. E. Noah, CMS Tracker Week, January 2003 Measurements on the APV25 Dependence on mode register: –With no trigger applied, I 125 and I 250 are constant, independent of the mode register setting. –Increase in current is: Independent of inverter stage Higher for 20MHz multiplexer frequency Slightly higher in peak mode

5. E. Noah, CMS Tracker Week, January 2003 Measurements on the APV25 Dependence on IPSP, VPSP and ISHA Virtually no dependence on any of the other bias generator settings:  Current drop when the trigger is removed probably occurs in the APSP (pulse shape processor).

6. E. Noah, CMS Tracker Week, January 2003 Measurements on a Hybrid 4 x APV module Measure: –Hybrid current with clock and trigger –Hybrid current with clock but without trigger –Hybrid current without both clock and trigger Check that measurements are consistent with those carried out on the stand alone APV25.

7. E. Noah, CMS Tracker Week, January 2003 Measurements on a Hybrid By switching off the analogue bias on any combination of APVs, consistency with the results obtained on ‘stand alone’ APV is confirmed.  drop occurs in APVs When the clock is removed, the decrease in current is much larger because of current drop in digital circuitry.  I dig = 85mA

8. E. Noah, CMS Tracker Week, January 2003 Measurements on a Hybrid Dependence of current drop on bias register settings when the trigger is removed Dependence of current drop on bias register settings when the clock is removed

9. E. Noah, CMS Tracker Week, January 2003 Comparing Measurements Hybrid measurementsAPV25 measurements Dig. headerAnalogue baseline Decreasing VPSP:  higher baseline  larger current drop

10. E. Noah, CMS Tracker Week, January 2003 Trigger Rate Dependence Measurement is made by: –Applying trigger at a rate defined by external pulse generator. –Recording maximum and minimum power supply currents. For trigger rates above 10 Hz, hybrid current is stable.

11. E. Noah, CMS Tracker Week, January 2003 Summary I 250 drops with low trigger rates applied to hybrids: –Trigger removal initiates a current drop which occurs with a time constant of ~ seconds. –When trigger is applied, current rises rapidly. Effect originates in the APVs, probably the APSP since it is sensitive to VPSP, IPSP and ISHA. For a hybrid operated with default settings and APV analogue baseline ¼ of digital header, drop in current is 10%. Effect of removing the clock was also measured: current drop is much larger because of contribution from digital circuitry.

12. E. Noah, CMS Tracker Week, January 2003 Strasbourg Results, 6-APV Hybrid Drop in current is large but note that VPSP=20, so baseline is high.

13. E. Noah, CMS Tracker Week, January 2003 Strasbourg Results, 4-APV Hybrid 4-APV hybrid, same bias register settings as those used at IC. Similar current drop but time constant is much larger.

14. E. Noah, CMS Tracker Week, January 2003 Effect of removing the clock on Hybrid  I tot =  I dig +  I ana  Case 1:Trigger is removed.   I dig = 0   tot =  I ana = 51mA  Case 2: Clock is removed.   I tot = 136 mA   I dig =  I tot –  I ana = 85 mA  APV manual states 164  A/channel, 21 mA/chip  Drop due to digital circuitry is constant.