2 - rt2010_hf
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Transcript 2 - rt2010_hf
A scalable DAQ system using
the DRS4 sampling chip
H.Friederich1, G.Davatz1, U.Hartmann2, A.Howard1,
H.Meyer1, D.Murer1, S.Ritt2, N.Schlumpf2
1 ETH Zurich, Switzerland
2 Paul Scherrer Institute, Switzerland
Outline
1. Introduction
WaveDREAM Project
DRS4 Chip
2. Realization
Analog Frontend
Continuous Digitization
Digital Backend
3. Results
System Bandwidth
Noise Power Spectrum
System Nonlinearity
Hannes Friederich – May 2010
Slide 2
WaveDREAM Project
Motivation: 1 GSPS, 8-bit, low cost,
multichannel system for pulse shape
discrimination and photon counting
Development of a flexible DAQ system
Based on the DRS4 chip
Active amplification
20 dB gain
≥ 500 MHz bandwidth
Scalable no. of channels
Optimized for small amplitude (~10 mV), high frequency
signals (~1 GHz), e.g. PMT
Capability for 1 ns global event timestamps
Digital Trigger (FPGA)
General purpose board
Hannes Friederich – May 2010
Slide 3
DRS4 Chip (Developed at PSI)
FUNCTIONAL BLOCK DIAGRAM
Stores the analog waveform
up to 5 GSPS
11.5 bit SNR
Slower SCA readout
Less expensive ADC electronics
Region of interest readout
NumberOfBins x 30 ns
PLL
WSRIN
DENABLE
DWRITE
REFCLK
DTAP A0 A1 A2 A3
LVDS
DOMINO WAVE CIRCUIT
IN0
MUX
CHANNEL 0
OUT0
CHANNEL 1
OUT1
CHANNEL 2
OUT2
CHANNEL 3
OUT3
CHANNEL 4
OUT4
CHANNEL 5
OUT5
CHANNEL 6
OUT6
IN7
CHANNEL 7
OUT7
IN8
CHANNEL 8
IN1
IN2
IN3
IN4
IN5
IN6
WRITE SHIFT REGISTER
AGND AVDD DSPEED PLLOUT PLLLCK
ENABLE
Large Switched Capacitor Array
(SCA)
WRITE CONFIG REGISTER
OUT8/
MUXOUT
O-OFS
BIAS
ROFS
SROUT
WSROUT
STOP SHIFT REGISTER
RSRLOAD
SRIN
SRCLK
READ SHIFT REGISTER
MUX
RESET
CONFIG REGISTER
DVDD DGND
8+1 channels
Individual Channel depth 1024 bins
Channel cascading
Parallel or serial channel readout
Hannes Friederich – May 2010
Slide 4
DRS4 Transparent Mode
Input directly accessible at output while
recording
50 MHz Bandwidth
Continuous sampling of the input
Same ADC as DRS readout
Digital trigger
Arbitrary event record length
Eliminates the need for splitting the signal at the
frontend
Reduces PCB complexity
Transparent Mode gain:
½ of SCA gain
SCA
Hannes Friederich – May 2010
MUX
LP
Slide 5
Design Realization
Analog Frontend
Digital Trigger in the FPGA
(e.g. Threshold, CFD)
DRS4
ADC
Board-to-board
communication
FPGA
Readout of all 8 pipelines in parallel
Minimizes DRS4 dead time
Gigabit
Ethernet
UDP
connection
to backend
Board-to-board
communication
Hannes Friederich – May 2010
Slide 6
Analog Frontend
DAC
THS
4508
DRS4
50
THS
4302
50
50
baseline DC offset
+ 14 dB
+ 6 dB
AC coupled input
Fixed gain 20 dB
Adjustable baseline
Accommodates all signal polarities
Input remains in linear range of DRS4
Input span: 1 V p-p
Input levels between
0.1 and 1.5 V
Frontend-only bandwidth > 1 GHz
Hannes Friederich – May 2010
Slide 7
Continuous Digitization
AD9212
CLK
DRS4
FPGA
AD9212
Sample Modes:
- Continuous
sampling
(120 MSPS)
- DRS Readout
(30 MSPS)
Trigger
AD9212: 8 Channel, 10 bit ADC, 65 MSPS
Transparent Mode: 50 MHz bandwidth
Sampling theorem: ≥ 100 MSPS or additional low-pass
filtering
More bandwidth increases SNR for high-frequency pulses
Solution: 2 AD9212 with 180 degrees clock phase
shift, 120 MSPS
Hannes Friederich – May 2010
Slide 8
Global Timestamps
DRS4
FPGA
LP
Global Clock & Reference signal distributed to all boards
Avoids clock skew
Use clock conditioner chips to reduce clock jitter
Sample the reference signal in the DRS4 to extract fine-grain
timestamps
Calibrate propagation delays
Not tested – No numbers
Hannes Friederich – May 2010
Slide 9
Prototype Implementation
Mezzanine Card
Analog electronics, DRS4 chip, ADCs
Carrier Card
Slots for 2 mezzanine cards
2 FPGAs (Xilinx Spartan 3A)
Communication Layer
Gigabit Ethernet
UDP / IP / MAC layer in VHDL
Board-to-board communication
960 Mbit/s
USB 2.0
RS-485
VME form factor (6U)
Provides mechanical support,
power supply & cooling
No support for VME bus
Hannes Friederich – May 2010
Slide 10
Results: System Bandwidth
Input capacitance of DRS limits bandwidth
500 MHz Bandwidth
Nonlinear amplification around 300 MHz
Hannes Friederich – May 2010
Slide 11
Transparent Mode Bandwidth
Bandwidth [-3dB]: 60 MHz
Hannes Friederich – May 2010
Slide 12
Noise Power Spectral Density
DRS Readout (1.024 GSPS)
ENOB 8 – 8.5 bit
Hannes Friederich – May 2010
Slide 13
Baseline Adjustment
ADC range [0 1024]
Baseline can be adjusted
Linear adjustment circuit
Hannes Friederich – May 2010
Slide 14
Amplitude Nonlinearity
Amplitude Nonlinearity less than 1 ADC value
Hannes Friederich – May 2010
Slide 15
Applications
A performant system has been demonstrated
Possible applications include
Pulse shape discrimination
Photon counting from PMTs
Oscilloscope functionality
Arbitrarily flexible trigger logic in the digital domain
Window coincidence already implemented
If you’re interested in using the WaveDREAM board,
please contact me afterwards
Hannes Friederich – May 2010
Slide 16
PMT Signals
First part of
transparent mode
signal equals DRS
readout signal
Hannes Friederich – May 2010
Slide 17
Conclusion
A challenging design realized
Good bandwidth achieved (500 MHz)
Region of interest sampling up to 5 GSPS
120 MSPS continuous sampling
Digital Trigger logic
ENOB 8 - 8.5 bit
Gigabit Ethernet
Cost Effective
Flexible design for multiple applications
Thanks to Arktis Radiation Detectors Ltd & CTI for
financial support
Hannes Friederich – May 2010
Slide 18
Hannes Friederich – May 2010
Slide 19