Download Version 1 - MICRHAU

Charge Sensitive Amplifier (CSA) in cold gas of Liquid
Argon (LAr) Time Projection Chamber (TPC)
Context
Detector
Specifications :
• Multichannel 3fC to 120fC (0.5μs pulse) Charge Sensitive Amplifier
• Less than 1500 e- ENC with 250pF Detector capacitance (Signal/Noise ratio of 10)
• Able to work in LAr vapours @ -150°C with an affordable power dissipation :
1mW/channel, considering a power pulsing rate of 2.5% (effective consumption : 40mW)
• Low cost highly integrated solution implies an ASIC CMOS process circuit.
Charge Sensitive Amplifier
shaper
-A
buffer
H
CD
250pF
Cpa
Rpa
H ( p) 
Ho  p
(1    p) 2
τ= [0.5; 1; 2 ;4]µs
Input current
CSA output
500ns
Shaper output
500ns
500ns
Physic experiment :
•A near detector (from the Hardron target) will allows physic experiments as well as electronic experiments for larger scale detectors (100 kilotonnes )
Noise
4 chips comparison
Noise summary
[** OUT_PA-noise **]
Device
Param
Noise Contribution
/MP34
id
0.000417014
1
/MN8
id
0.000292864
2
/MN8
fn
0.000186043
/MN180 3
id
0.000185096
/MN19 4
id
0.000155535
/MN180
fn
0.000144948
/MP36
id
0.000129472
/R1/R2
thermal_noise 0.000128369
5
/R1/R1
thermal_noise 0.000128365
/R27
rn
0.00012745
/MN33
id
0.000112945
/MP1 6
id
0.000109437
/MP2 7
id
0.000101267
/MN19
fn
8.17541e-05
/MP33
id
8.03967e-05
/R5
rn
7.19811e-05
/MP123
id
6.79982e-05
R6.R2.rpolyh1 thermal_noise 6.73008e-05
/MP35
id
6.48913e-05
/MP34
fn
5.46878e-05
R6.R1.rpolyh1 thermal_noise 5.10705e-05
/MN32
id
5.08948e-05
R3.R2.rpolyh1 thermal_noise 4.92785e-05
R3.R1.rpolyh1 thermal_noise 4.25442e-05
R4.R1.rpolyh1 thermal_noise 4.15188e-05
R4.R2.rpolyh1 thermal_noise 3.98648e-05
R2.R1.rpolyh1 thermal_noise 3.98639e-05
R2.R2.rpolyh1 thermal_noise 3.97519e-05
/I10/MP1
id
3.08658e-05
6
7
1
5
2
3
4
% Of Total
32.85
16.20
6.54
6.47
4.57
3.97
3.17
3.11
3.11
3.07
2.41
2.26
1.94
1.26
1.22
0.98
0.87
0.86
0.80
0.56
0.49
0.49
0.46
0.34
0.33
0.30
0.30
0.30
0.18
•Version 1 detailed in [1] has no integrated shaper. With an
external shaper, noise reaches 1100 e- at -110°C.
•Version 2 has a default in the amplifier of the shaper. A redesign was necessary.
•Version 3: Modified CSA using Gain Boost technique[2].
Stability issue due to a bad sizing of the compensation
resistance. Results : higher noise at low temperature
•Version 4 is range limited because the intrinsic gain had
been voluntary increased
Charge Sensitive Amplifier
Version 4 configurations :
-A
C
•Cpa : 250 or 500fF
R
•Rpa : 1, 2, 3 or 4MΩ
•Shaping center frequency : 0.5, 1, 2 or 4 µs
Shaper
H
pa
pa
Integrated Noise Summary (in V) Sorted By Noise
Contributors
Total Summarized Noise = 0.000727636
Total Input Referred Noise = 0.493965
Fully digital ‘I2C-like’
configuration protocol
 Chip v4:
Noise comparison
of the CSA with
ideal bias current (PA1^2)
versus
fully designed CSA (PA^2)
 Chip v4:
Histograms measure of the noise could be experimentally observed out of
the ADC with the DAQ system [3]. The delta : 5.4mV corresponds to FWHM/2
(Full width at half maximum). Since the rms Noise (σ) ~ FWHM/2.35
We verify that "sqrt-integ-noise**2" maximum value : 5.32 ~5.4mV*2/2.35
CSA Shaper Buffer
Version 1 : PA_TOP
1654µm X 1664µm=
2.75mm²
Version 2 : TOP_EST
1974µm X 2364µm=
4.66mm²
Version 3 : TOPPING
1914µm X 2544µm=4.876mm²
Version 4 : T2K_V4
1914µm X 2684µm=5.14mm²
Experimental application
 Chip v4:
MIP signal with oscilloscope persistence
32-channel
2000
 Experimental results of various versions chips.
- First version noise is better since the shaper was external.
- For the latest version, a noise reduction is obtained by cooling
down the chip at the level of the actual detector capacitance.
20
18.9
Charge Sensitive Amplifier
18.6
18.1
1915
1799
1800
-A
18
H
Cpa
buffer
Rpa
16
14.0
14
1600
1584
1524
1400
-200
8 channels x 4 chips =32 channels per pane.
3 pane in the LAr tank (vapours) one outside
12
AVERAGE ENC (e-)
Gain (mV/fC)
10
-150
-100
-50
0
50
 Chip v4:
Measurement from room temperature
down to LN2.
Conclusion
Shaper
•Application in a joint test with LHEP Bern
and Perspectives
•Evident difficulties of prototyping a circuit without models at low temperature (-150°C)
•Improvement on the consumption at equal noise level are under study. Effort on
biasing element could be profitable.
•A low quiescent current buffer is under test.
•Specifications fulfilled.
•An investigation on the AMS 180nm will be done when the technology will be available.
•A 128-channel test (4 cards of 4 chips of 8 channels) on a detector with a digital
acquisition [3] system will be published rapidly.
•When the design will be validated, a 32 or 64-channel chip will be submitted.
[1] CMOS Charge amplifier for liquid argon Time Projection Chamber detectors, E. Bechetoille, WOLTE08, Jena, Germany. http://hal.in2p3.fr/in2p3-00339737/
[2] Feedforward compensation techniques for high-frequency CMOS amplifiers, W. Sansen,
[3] MicroTCA implementation of synchronous Ethernet-Based DAQ systems for large scale experiments, C. Girerd et al. RT2009, Beijing, China. http://hal.in2p3.fr/in2p3-00394783/
E.Bechetoille, H. Mathez, Y. Zoccarato
IPNL, 4 rue E. Fermi 69622 Villeurbanne, France — University Lyon 1, CNRS/IN2P3, MICRhAu
contact : e.bechetoille (at) ipnl.in2p3.fr
http://micrhau.in2p3.fr/
NSS-MIC 2010 - 2010 IEEE Nuclear Science Symposium and Medical Imaging Conference - Knoxville, Tennessee, 30 October – 6 November 2010
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