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Hall D Drift Chamber Electronics
FJ Barbosa
Electronics for CDC and FDC
Hall D
F.J. Barbosa, Jlab
1.
2.
3.
4.
5.
6.
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8.
9.
Central Drift
Chambers (CDC)
Motivation
ASIC Development
Preamp Cards
Cabling
Cooling
fADCs
TDCs
HV, LV & Grounding
Summary
Forward Drift
Chambers (FDC)
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
1.
A Brief Summary of Specifications
Motivation
CDC
Type
Channel Count
Straw
3200 anodes
Physics Signal
Time Resolution
Detector Gain
Dynamic Range
225 e
15%
2 ns
2 x 104
100 fC → 3 pC
dE/dx
Preamp Gain
Yes
2 mV/fC
Single Channel
Rate
TDC
115 ps
fADC
12-bit, 100MSPS
3kHz - 100 kHz
Energy Resolution
No
Yes
Drift Chamber Review
6-8 March 2007
FDC
Planar
2304
anodes
9216
cathodes
94 e
15%
1 ns
105
300 fC → 3pC anodes
10 fC → 1 pC cathodes
No
2 mV/fC anodes
10 mV/fC cathodes
< 280 kHz anodes
< 600 kHz cathodes
anodes: Yes
cathodes: No
anodes: No
cathodes: Yes
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Hall D Drift Chamber Electronics
FJ Barbosa
Generalized Readout Electronics
Preamp
Pipelined DAQ
Ionizing Track
+HV
Cathode Strips
R
fADC
++ +
--- - --
FDC
C
Disc
TDC
+ +
+
fADC
Anode Wire
For the cathode strips, q+ ~ 1/5 q-
Ionizing Track
+HV
Straw Tube
CDC
++ +
--- - --
C
fADC
+ +
+
R
Anode Wire
Drift Chamber Review
GND
6-8 March 2007
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Hall D Drift Chamber Electronics
2.
FJ Barbosa
Application Specific Integrated Circuit (ASIC) Development
• The GlueX Preamp ASIC is Being Designed by Mitch Newcomer at U. Penn.,
the Designer of the ASDQ ASIC – used at CDF at FNAL.
• This Development is Based on the ASDQ ASIC:
Preamp,
+
Input
-
Protect
Shaper &
Discriminator
& dE/dx
BLR
Output
Driver
ASDQ Functional Blocks
+
-
ASDQ Photomicrograph
• The ASDQ ASIC was Fabricated in a Bipolar Technology which is
no Longer Available (Maxim SHPi).
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
The GlueX ASIC
• The GlueX ASIC Will be Fabricated Using the 0.25 µm TSMC CMOS Process.
Block Diagram of the GlueX ASIC Prototype:
Inputs
+
Input
-
Protect
Preamp
Shaper
Output
Driver
+
-
Outputs
• Input Protection – Protects Inputs from Discharge Spikes. →
• Preamp - Amplifies Detector Signals with Minimal Signal
N input
Shaping.
• Shaper – Ion Tail is Shortened by Pole-Zero Filtering Which
P input
Improves High Rate Operation.
• Output Driver – Provides Drive for Signals Through Cables.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
Differential Output Amplitude (mV)
Some Simulation Results of the GlueX ASIC
Linearity is
Maintained to a few %
in the 0 - 400 fC Range.
• Output Linearity is Within a Few % Over the Range of Interest.
• ENC Has Been Simulated to be Nominally 2500 e + 50 e /pF,
-
-
as a Function of Detector Capacitance.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
The GlueX ASIC
Summary of Specifications
Channels
Inputs
Type
Dual (+ and -)
Impedance
80 Ohm
Protection
Diode Protected
C Range
10-100pF
Shaping
Peaking
Time
11ns @ 10pF Cin
Unipolar – [CR-RC3]
Outputs
Type
Differential, Offset Bias
Range
0-1000 mVp-p
(-425mV to +575mV
Cascodes
440um
8
Gain
Input
Transistors
Noise
2mV/fC
Range
0-400 fC Impulse or Point
Ionization
ENC
2500 e + 50 e/pF
Power
Supply
+2.5V
Power
320 mW (40mW/Channel)
Process
0.25µm CMOS TSMC
Die Size
2.4mm x 3.2mm
Packaging
QFN64 10x10 mm
212um
One Channel Layout
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
Status of the GlueX ASIC Prototype:
• Design and Layout Have Been Completed.
• Design Rule Check (DRC) is Underway.
• Design will be Submitted to MOSIS by Middle of March.
• MOSIS will Perform a Final DRC Before Fab Run.
• TSMC Run, Through MOSIS, on 9 April 2007.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
Future Developments for the GlueX ASIC
• We will be testing the prototype GlueX ASIC Preamp during the
Spring and Summer of 2007.
• What Will We Get?
 1. Valuable information about the analog section on about
40 chips.
 2. Validate the simulation models and the TSMC Process.
 3. Verify proper operation with realistic detector conditions
and adjust parameters as necessary:
 Tests will be conducted on the FDC and CDC Prototypes.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
• Towards the Final Design of the GlueX Preamp
• Design work will continue for the next year:
 Shaping Control – Allows tailoring of the ASIC characteristics
to various detector characteristics.
 Discriminators – Will be Added to Accommodate the FDC
Anodes → Lower Cost
→ No External Discriminators.
 Gain Control – Will be Added to Accommodate the FDC
Cathodes.
Simplified Diagram of the Final GlueX ASIC
ASIC
Diff. outputs
Gain
Shaping
Vth
Amp/Disc
Drift Chamber Review
6-8 March 2007
← 5 Pins Common to 8 Channels
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Hall D Drift Chamber Electronics
3.
FJ Barbosa
Preamp Cards
Major Design Considerations
• Space Constraints
 Geometry of the Detectors, Cables,
Gas Lines, Mechanical Structures.
 The preamp card has to fit the FDC space requirements,
which are the most severe of the wire chambers.
• Cooling
 Cooling of any detector electronics is severely constrained
due to limited space.
• Serviceability
 It is desirable to replace preamp cards with minimal down time.
• Standardization
 It is desirable to have a single preamp architecture.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
Layout of the GlueX 24-Channel Preamp Card
 Components on both sides of the PCB.
Input Protection
GlueX ASIC
 There are two ASICs on the top side
and one on the bottom side.
 A supply regulator is on the bottom side.
 Material is FR-4, 4-layer and
0.8 mm thick.
50-pin
Output Connector
Top View
 The 25th pair of pins will be used for
pulse calibration.
Input Connector
(located on translator board)
Drift Chamber Review
6-8 March 2007
 Power Dissipation = 1.152 Watts
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Hall D Drift Chamber Electronics
FJ Barbosa
4.
AMPHENOL SPECTRA-STRIP
50-Conductor Cable
Cabling
FDC
Twisted-Pair Impedance = 90 Ohm
• We
are considering this
cable for its dimensions and
electrical characteristics.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
5.
FJ Barbosa
Cooling
CDC
The Four
FDC Packages
Are Located in
This Region
Cables are
Routed Out
From the
CDC
Cables are
Routed Out
Uniformly
Over the
Surface of
the FDC
• The FDC Has 11,520 Preamp Channels  480 Preamp Cards
►► 553 Watts.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
Barrel
Calorimeter
Output
Connector
Cable
Copper Braid
0.030” x 0.625” x 5”
5 cm
Cooling System
Radiator Block
ASIC
Preamp Card
Input
Connector
• Cooling will be effected by heat conduction
from the preamp cards to the cooling system.
• We also want to minimize convective
6 mm Gap
losses to ambient air.
• We are investigating various options as
FDC Package
(Side View)
forced air is not adequate for cooling
the preamp cards.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
FJ Barbosa
Temperature Profile of the GlueX Preamp Card – Simulation at Ambient Temperature of 25 ºC
120 ºC
120 ºC
40 ºC
40 ºC
Still Air: ASIC Tj = 103C
Conductive Cooling: ASIC Tj = 75C
• The preamp cards should not be operated without cooling provisions.
• Conductive cooling is effective at removing heat from the card.
• However, thermal performance is marginal as we would like to operate at
lower Tj for improved reliability margins.
• An improved cooling system must be considered …
… low pressure liquid cooling?
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
6.
FJ Barbosa
fADCs
• A flash ADC is currently under development for the CDC and FDC:
 72 Channels
 12-bit Resolution
 80 or 105 MSPS (depending on final chip selection)
 Differential Inputs
 2048 (19.5 μS) Acquisition Buffer
 Calibration Pulsing of Detector Electronics
• Programmable Window and Latency.
• Shaping and anti-aliasing input filter for cable loss equalization and low noise.
• VME64X & 2eVME (~320 MByte/s).
• A prototype board of the frontend shaping filter is being tested with
the FDC prototype.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
7.
FJ Barbosa
TDCs
• The F1TDC is a Multi-hit TDC developed
at Jlab.
• VME64x Standard.
• 64 Channels – 115 ps rms.
• 32 Channels – 60 ps rms.
• Over 90 Modules in Use at Jlab.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
8.
FJ Barbosa
HV, Low Voltage & Grounding
CDC
FDC
1 TDC Rack
3 fADC Racks
1 fADC Rack
3 Racks for
4 Racks for
-HV
-Low Voltage
-Monitoring
-Controls
-HV
-Low Voltage
-Monitoring
-Controls
on Lower Level
• Cables are Shielded, Grounded & Routed to Minimize Exposure to Workers.
• Electronics Racks are Located Adjacent to Each of the Detectors.
• Platforms & Racks are Connected to Common Experiment Ground.
= Safety
•Multiple Levels of Power Supply Current Limiting and Fusing.
Drift Chamber Review
6-8 March 2007
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Hall D Drift Chamber Electronics
9.
FJ Barbosa
Summary
• ASIC - Test the Prototype and Finalize the Design.
• Preamp Card - Will be Revised to Reflect the Final Design of the
ASIC.
• Cooling System - Will be Carefully Considered Based on Cabling,
the Heat Load Due to the CDC, FDC and the other Detectors.
• fADC - Development Will Continue Over the next Year and
Prototype Tests Will be Used to Optimize the Design.
• TDC - Will be Modified to Accept LVDS Input Signals and
To Provide Calibration Pulsing to the Detectors.
Drift Chamber Review
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