conx – xeus meeting panu helistö, mikko kiviranta utrecht, 26-27.10.2004
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VTT TECHNICAL RESEARCH CENTRE OF FINLAND
VTT Board
VTT Electronics
VTT Information Technology
VTT IndustrialSystems
VTT Processes
VTTBiotechnology
VTT Buildingand Transport
Technical Research Centre of Finland
(VTT)
TTE Board
Microelectronics
Microsensing
Tele-communications
Networks
InformationSystems
Media
Human Interaction
TechnologiesInformation Technology
(TTE)
MEMS Sensors
RF Sensors
Quantronics
Optical Sensors
Biosensors
Microsensing
Thin film technology
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
Quantronics and thin film technology
Quantronics• Heikki Seppä• Panu Helistö• Juha Hassel• Mikko Kiviranta• Arttu Luukanen
(at NIST until mid2005)• Antti Niskanen• Jari S Penttilä• Hannu Sipola
Topics• Superconducting sensors, electronics
and standards (SQUID, Josephson voltage, bolometers)
• Mesoscopic electronics (BOT, sluice Cooper pair pump)
• Optimised and integrated readout electronics (e.g. for MEMS sensors and bolometers)
• R&D projects related to electricity metrology
• STJ detectors (X-ray for ESTEC, protein flight-time mass spectroscopy)
Thin film technology• Ilkka Suni• Markku Ylilammi• Leif Grönberg• Clean room
technicians
• 1700 m2 class 10/100 clean room
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
SQUID sensors
• SQUID (superconducting quantum interference device) is the most sensitive magnetic field sensor
• Almost 20 year background in SQUID applications
• Novel SQUID and readout concepts: unSQUID, hgSQUID, noise cancellation,…
• Industrial standard SQUID process
• World leader in biomagnetic SQUIDs
• SQUID - ‘ideal’ for reading out cryogenic calorimeter and bolometer signals – (low4 power, impedance, noise, temperature)
SQUID
Amplified signal is fed into the readout electronics
Superconducting ring,inner diameter ~ 2 m
Josephson tunnel junctions
Magnetic field in the loop changes the phase of the quantum wave function and changes the current through the ring
Bias current
Quantronics
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
Comparison of multiplexing methods for TES calorimeter readout
• Extensive theoretical evaluation in collaboration with SRON (mostly unpublished work)
• Conclusions: Frequency Division Multiplexing better than Time Division Multiplexing due to better scalability (in bolometer mode both are equal)
• XEUS requirements difficult but feasible from readout point of view
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
SQUID readout for TES calorimeters
mK SQUID design for XEUS X03 TRP
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
SQUID readout for TES calorimeters: dcSQUID
Washer SQUID• Flux noise about 0.1 0 / Hz at 0.4 K
Readout noise, measured atupper and lower point with dVo / dPhi = 0
DUT flux noise at dVo / dPhi = 3.0 V/Phi0
3.0
1.7
0.94
0.53
x 10-7 0 / sqrt(Hz)
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
SQUID readout for TES calorimeters: unSQUID
(a) Schematics of the damping circuit for the un SQUID.
(b) Chip carrier with the SQUID chip and SMD components.
(c) The time trace of the SQUID current taken in the negative-resistance region indicates stable operation without parasitic oscillation.
Potentially lower noise, improved impedance matching
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
SQUID readout for TES calorimeters: arraySQUID
Arrays SQUID
• Flux noise about 0.35 0 / Hz with direct RT readout
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
Low noise SQUID readout for multiplexing applications: bolometer readout
1. THz-range 4 K superconducting bolometer
2. Optimized, FDM compatible SQUID readout
3. Photon limited noise at room temperature
• NEP < 5 fW/Hz1/2
• => NETD <~ 10 mK/Hz1/2
• => Tres ~ 0.3 K @1 kHz
• => video rate imaging feasible
Univ.Jkl
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
Low noise SQUID readout for multiplexing applications: bolometer readout
Room temperature LNA
• 5 MHz center frequency
• Noise temperature 26 K @ 50 Ohm
SQUID amplifier
• input current noise 2 pA/Hz1/2
• => bolometer noise limited, 2 fW/Hz1/2
0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,870
80
90
100
110
120
130
140
I(A
)
V(mV)
Bolometer current
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
Low noise SQUID readout for multiplexing applications
Room temperature AC LNA Flow cryostat with optical windows
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
XEUS/FDM readout challenges
• Amplifier reading out the TES• Noise temperature <= 100 mK @ 10 MHz (SQUID)• Post-SQUID next stage easily dominates noise
• AC biasing/multiplexing• Low impedance levels: very high Q-value filters required• Dynamic range/linearity
• Idle current cancellation• Neg-FB with high loop gain when cable delay is present FB at
baseband, non-standard loop filters.• Effect of higher harmonics• Crosstalk
• Others• Count rate/pileup management• …
VTT TECHNICAL RESEARCH CENTRE OF FINLAND
Work division in ConX/XEUS technology development
Different possibilities
• Instrument1: ESA
• Instrument2: USA
• TDM based path
• FDM based path
• calorimeter1 SQUID1+LNA1 FDM
• calorimeter2 (SQUID2)+LNA2 TDM
• etc
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