Transcript SBS Collaboration Meeting June 3-5, 2013 Initial Evaluation of MQT Electronics R. Chris Cuevas 1. Hardware  2. Test Results   3. Overview Brief comparison to 1881 QDC Open issues(Questions) Summary.

SBS Collaboration Meeting
June 3-5, 2013
Initial Evaluation of MQT Electronics
R. Chris Cuevas
1.
Hardware

2.
Test Results


3.
Overview
Brief comparison to 1881 QDC
Open issues(Questions)
Summary
Charge-To-Time-Converter (MQT)
•
•
The 32 channel MQT circuit board was designed for the Belle Detector
The boards included the use of the LeCroy MQT300A integrated circuit
-- The MQT boards were used to readout the Central Tracking Chamber (CDC)
-- The CDC used a single ended preamplifier designed by Radeka
28 Pin Plastic Leadless Chip Carrier (PLCC)
Single channel IC
2
32 Channel MQT Board
400mm
9U
16 Channel single ended input card
(Makes testing easier)
3
32 Channel MQT Board Block Diagram
From PMT
NOT Preamp
For Hall A
application
To
1877
Could be used
For LED test
pulse
Not
Used
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Charge-To-Time-Converter (MQT)
•
•
Relatively simple circuit sections and the boards are in excellent condition
We built a simple 16 channel coaxial input board to facilitate the testing for each
channel.
• Inputs are at the rear of the board on standard DIN connectors
• Output (ECL) signals are on the front panel and connect to 1877 TDC
• The MQT chip is not so simple and there are a number of control bits to set the
desired charge input range.
-- In contact with Dr. Richard Sumner (One of the original LeCroy members)
• Analog input section is a voltage gain of ~50 and the analog signal passes
through a shaper and delay before being applied to the MQT chip
• Copy of the analog pulse is sent to a two threshold discriminator
-- This signal is delayed and creates a GATE signal of ~600ns
-- Analog (Charge) pulse is delayed so charge edge is 80ns after GATE edge
-- Note that the Max GATE from the MQT data sheet is exceeded by 50ns
-- The discriminator output is OR’ed with the MQT output so initial edge of
Channel output can be used in the TDC for timing.
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MQT Board Testing
6
MQT Board Testing
Horizontal == 100nx/div
Zoom in of pulse arriving after GATE
Internal self-Gating signal
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MQT Board Testing
Horizontal == 100nx/div
(Large Pulse)
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Test Notes
•
CR – RC shaping time is not optimized for pulse I was using from the generator.
•
Presumably the shaper section was optimized for the CDC peaking time in
conjunction with the gain from the Radeka preamp. I did not make many
adjustment to the pulse shape, but the shaper will differentiate if overdriven.
•
Need to understand how to control the range pins of the MQT300A chips. The
default is medium, but this may not be the best setting.
•
The MQT board requires seven (7) different power supply voltages!







-8V @ 1.3A
+15V @ 1.2A
-12V @ < 1A
-5.2V (Vee) @ 5.39A
+5V (Vcc) @ < 1A
Vthresh-High  0-10V [ 0 – 1V discrimination range ]
Vthresh-Low  0-10V [ 0 – 1V discrimination range ]
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Test Notes
•
We refurbished an older 9U by 400mm ‘crate’ from the CLAS6 drift chamber
-- The size of the crate was perfect
-- The card guides and crate provided adequate cooling
-- The 7 power supplies for the MQT boards was less than optimal and the
-8V supply was only biased to -5.2V which was inadequate.
-- The two threshold supplies were NOT biased from the Vicor supply
-- In the end it was decided to power a single board and study the circuits closer
on the bench.
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Additional Testing Needed
•
Configure the range control for the MQT chips so that all three ranges are ON.
•
Understand the output pulse train from the MQT given a calibrated input charge
pulse.
-- Verify conversion time for MQT charge
-- Verify maximum rate performance
•
On board GATE time seems excessive and exceeds the specification of the
MQT300A chip. Can be adjusted but will require component changes.
•
Once pulse train output is understood and stable with a calibrated charge input,
setup test with MQT board and FastBus 1877 to begin decode.
-- First edge of MQT output pulse train is the discriminator edge and will be
used for timing measurement. 1877 is 500ps LSB
-- Remaining pulse train edges will need to be decoded and converted to derive
charge value
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Brief Comparison to 1881 FastBus ADC
# of Channels
64
# of Channels
32
Input Type
Coaxial single ended
Input Type
Coaxial single ended
Dynamic range
13 bit
Dynamic range
12 bit
Sensitivity
50 fC/count
10 fC/ns to 640fC/ns
Conversion Time
12us (all 64 channels)
Sensitivity
*3 ranges
Full scale
8192 counts (410pC)
Conversion Time
6us
64 event buffer
YES (FastBus
module)
Full scale
2620pC
Event buffer
NO (Custom bus)
1881 Board
MQT Board
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More Comparisons
Detector (PMT)
MQT Board
1877 TDC (96 channels or 3 MQT)
NO splitter
NO delay cable (1877 operated in common STOP)
Custom (High current) power supply and crate
Discriminated signal AND Charge pulse information
GATE
Splitter
Delay
1881 ADC
Detector (PMT)
Discriminator
1877 TDC
STOP
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Summary
• Initial testing was preliminary
• Good understanding of all MQT circuit board sections
• Significant questions and testing remain
? Understand MQT chip pulse output stream for each range
? Use calibrated charge to verify MQT conversion to 1877
? What will PMT pulse shape parameters be for nominal amplitude signal
? Will CR-RC shaper on MQT need significant adjustment
• Power supply for MQT boards is not standard and will need fairly large current
for a full crate of MQT boards (Still less than FastBus crate)
• Acknowledgements
Bill Gunning for test and crate configuration
Mark Taylor for quick design of 16 channel coax input test board
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