LCFI meeting 19 th August 2008 TESTING OF CPR2A Mirek Havranek, Peter Murray, Konstantin Stefanov, Stephen Thomas

2 LCFI meeting 19 th August 2008 INTRODUCTION  CPR2A provides read-out for column parallel CCD  126 voltage channels & 123 charge channels (spread in 2 parts)  5-bit ADC  Cluster finding logic  7-bit digital threshold for each column  Should be able to work with 50 MHz clock (same like CCD clock)  Stand-alone testing possible

3 LCFI meeting 19 th August 2008 ADC CHARACTERISTIC OF V-CHANNEL  Response of ADC to step voltage input signal is linear  Missing codes are significant at low reference voltage level  3 mV corresponds to 2000 electrons  Noise level at VREF = 200 mV was ± 1 LSB

4 LCFI meeting 19 th August 2008 ADC CHARACTERISTIC CH-CHANNEL  Charge amplifiers work well - not like last version of the chip  Higher number of missing codes is given by low VREF (measured lower charge compare to last slide)  100 mV input voltage corresponds to 1250 electrons NOISE DISTRIBUTION

5 LCFI meeting 19 th August 2008 FLUCTUATION  Response of all channels to the same signal level (differs for voltage and charge channels)  1 – 126 are voltage channels and 127 – 249 are charge channels  Step in the middle of charge amp. region is correct – there is change of feedback capacitance

6 LCFI meeting 19 th August 2008 DIGITAL TEST OF CPR2A  Simulated input data can be sent to the scan register in CPR2A a processed by on-chip cluster finding logic  Cluster finder looks after clusters 2 by 2 pixels and read data from pixels around  The smallest read-out area is 6 by 4 pixels (6 in vertical direction)  Dimensions of read-out area depends on cluster sum  Current version of decoder allows to reconstruct data from frames with low occupancy

7 LCFI meeting 19 th August 2008 RECONSTRUCTED CLUSTERS  Cluster sum = 45, cluster threshold = 40  No errors found (even when the cluster is surrounded by noise -> look at the backup) CPR2A input CPR2A output

8 LCFI meeting 19 th August 2008 RECONSTRUCTED CLUSTERS  High cluster sum relative to threshold  Cluster sum = 110, cluster threshold = 40  No errors found (even when the cluster is surrounded by noise -> look at the backup) CPR2A input CPR2A output

9 LCFI meeting 19 th August 2008 SIMULATION DATA Provided by Stephen Thomas

10 LCFI meeting 19 th August 2008 RECONSTRUCTED MATLAB DATA  Successfully reconstructed input data over threshold = 39  Various shapes of clusters are observed CPR2A input CPR2A output

11 LCFI meeting 19 th August 2008 RECONSTRUCTED MATLAB DATA  At threshlod level = 15 most of clusters is reconstructed – unfortunatelly cluster decoder in LabVIEW is not still fully compatible with output data CPR2A input CPR2A output

12 LCFI meeting 19 th August 2008 SUMMARY  Analog test - voltage and charge channels produce linear response with acceptable amount of missing codes and low noise - good functionality was verified at 1 MHz clock frequency - at higher frequency (> 5 MHz) noise level has significant part of dynamic range - next problem are big fluctuations across all channels  Digital test - digital test is still in progress - cluster finding logic works well at low occupancy - any significant mistake in cluster finding logic wasn’t find

LCFI meeting 19 th August 2008 THANK YOU FOR ATTENTION

14 LCFI meeting 19 th August 2008 BACKUP  Reconstructed clusters with noise – clusters one time over threshold  Cluster sum = 45, Cluster threshold = 40 Note: to zero value in output correspond grey color instead of white – it was used for visualization purposes

15 LCFI meeting 19 th August 2008 BACKUP  Reconstructed clusters with noise – clusters two times over threshold  Cluster sum = 110, Cluster threshold = 40 Note: to zero value in output correspond grey color instead of white – it was used for visualization purposes