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Gossipo-3: a prototype of a Front-end Pixel Chip for Read-out of Micro-Pattern Gas Detectors .

Gossipo-3: a prototype of a Front-end Pixel Chip for Read-out of Micro-Pattern Gas Detectors. Vladimir Gromov. Christoph Brezina 2 , Klaus Desch 2 , Harry van der Graaf 1 , Vladimir Gromov 1 , Ruud Kluit 1 , Andre Kruth 2 , Francesco Zappon 1

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Gossipo-3: a prototype of a Front-end Pixel Chip for Read-out of Micro-Pattern Gas Detectors .

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  1. Gossipo-3: a prototype of a Front-end Pixel Chip for Read-out of Micro-Pattern Gas Detectors. Vladimir Gromov Christoph Brezina2, Klaus Desch2 , Harry van der Graaf 1, Vladimir Gromov 1 , Ruud Kluit 1, Andre Kruth2, Francesco Zappon1 1National Institute for Subatomic Physics (Nikhef), Amsterdam, 2Institute of Physics, Bonn University TWEPP-09, Paris, France. September 22, 2009.

  2. Outline • Read-out of Micro-pattern gas detectors • Gossipo-3 prototype: functionality and features • Design and performance of basic circuits • Plans and perspectives TWEPP-09 V.Gromov 22/09/09 2

  3. Micro-pattern gas detectors: layout and features Gas-avalanche detector combining a gas layer as signal generator with a CMOS readout pixel array Cathode (drift) plane Cluster1 Cluster2 1mm …1m → Drift gap Cluster3 Gas Amplification Structure 400V 50um → Avalanche gap Readout chip Cpar Front-end circuit • - particle track image (projection) • 3D track reconstruction • no sensor leakage current compensation • low parasitic capacitance (less than 10fF) • - micro-discharges in avalanche gap TWEPP-09 V.Gromov 22/09/09 3

  4. Readout Chip for MPGDs GOSSIPO-2 • 2007: GOSSIPO-2 • - technology: 0.13μm CMOS • array: 16 x 16, 256 pixels • pixel: 55 um x 55 um • - active area: 0.88mm2 • event clock: 40MHz • high resolution TDC-per-pixel architecture (bin=1.8 ns) • - range: 350ns (4-bits @ 25ns) • 2009: GOSSIPO-3 / GOSSIPO-4 • - technology: 0.13μm CMOS • array: 32 x 32, 1024 pixels • pixel: 60μm x 60μm • active area: 3mm2 • event clock: 40MHz • accuracy (bin size): 1.73ns • range: 102μs (12-bits @ 25ns) • ToT accuracy: σ = 200e- (27ns) • ToT range: 6.4μs (8-bits @25ns) • Hit Counting mode • noise: σ = 70e- • fast response: 20ns (rise time) • power (goal): 100mW/cm2 (3μW/ch) GOSSIPO-3 GOSSIPO-4 TWEPP-09 V.Gromov 22/09/09 4

  5. Gossipo-3: MPW prototype Features each pixel measures: - hit arrival time → cluster’s drift time - time-over-threshold → charge deposit - number of hit (24 bits) triggering options: - external common stop read-out options: - serial read-out of all the pixels other functionalities: - auto clear (no stop signal after expected latency) - INGRID & pixel analog signal monitors Time mode Hit Counting mode TWEPP-09 V.Gromov 22/09/09 5

  6. TDC with local oscillator Hit signal Pixel_1 Clock signal (Fslow = 40MHz). Local oscillator Hit Nslow Start Start Out Stop Stop Stop Local oscillator output (Ffast = 640MHz) 40MHz Clock Bus Nfast Trigger signal Time = Nslow / freqslow + Nfast /freqfast Power ≈ Hit_Rate ● 6 μW / MHz per channel → 0.16 μW @ 27.2KHz TWEPP-09 V.Gromov 22/09/09 6

  7. Gossipo-3: the pixel Block diagram of the pixel Layout of the pixel Local fast oscillator (600MHz) 4 bit Fast counter Logic: counters & control 8 bit ToT counter Preamp Discr. control HIT pad oscillator 12 bit Slow counter -Threshold - Mask Time / Counting Threshold DAC Preamp & comparator DAC 6 bit Pixel configuration Memory • Control signals • Clock • TRIGGER (common stop) • TOKEN • RESET • LFSR = Counters • (data taking) • or • LFSR = Shift registers • (data read-out) TWEPP-09 V.Gromov 22/09/09 7

  8. Diagrams (TIME mode) State diagram Preamp_out Hit (asynchronous) ToT Clock (40MHz) Counter Fast Counter ToT Trigger Counter Slow Token Reset Data taking phase (LFSR = Counter) Data read-out Phase (LFSR = Shift Registers) TWEPP-09 V.Gromov 22/09/09 8

  9. Local oscillator :basic limitations EN 0ns…Tslow (25 ns) Tfast (1.72 ns) OUT NAND EN OUT Delay = Tfast/2 = Function (Temp, Vdd) 0…15 (4-bit TDC) VDD effect TEMP effect 2.2 2.1 2 1.9 1.8 1.7 1.6 2.2 2.1 2 1.9 1.8 1.7 Tfast ,ns Tfast ,ns 2% / 10 ◦C - 12% / 100mV Channel-to-channel statistical spread is 4% 1.05 1.1 1.15 1.2 1.25 1.3 0 20 40 60 80 100 Power supply voltage, Volts Temperature, ◦C TWEPP-09 V.Gromov 22/09/09 9

  10. Local oscillator : reproducibility Pixel-to-pixel mismatch σ(∆Tfast/Tfast) ≈ 2% ●(N●W ● L)-0.5 clock period =25ns Monte Carlo simulations. Tfast=1.73ns ∆tmax = 0.5ns (accumulated) Process variation TWEPP-09 V.Gromov 22/09/09 10

  11. Local oscillator: frequency tunability Common on-chip LDO: voltage regulator vdd=1.2V Uref 4bit DAC Opamp Bandgap Current Reference with Temp. Gradient U vdd_osc =0.6V…1.1V 1.14k Off-chip cap 10μF 2k • Functionality • - tunes oscillation frequency • power supply ripple rejection • temperature compensation TWEPP-09 V.Gromov 22/09/09 11

  12. The front-end 2.4/2.4 Input pad (22μm x 22μm) Ib = 6nA Uout Tfb 0.48/2.4 Cfb =Cds+Cdg+Cdb+Cdj ≈ 1 fF 170fF OPAMP Discharge protection Cpar ≈ 10 fF To Comp • Features • low time jitter, time walk • - constant current feedback (1nA) • - high gain (1mV / fF) Uin + Qin / Cfb Uout -Time●IsatTfb/Cfb Uin + 70mV exp[-Time/(Cfb●RonTfb )] Uin Time Tfb in saturation Tfb in triode TWEPP-09 V.Gromov 22/09/09 12

  13. The front-end circuit • Main specifications: • low power consumption (3μW/ch) • fast response (20ns) • - low noise (σ =70 e-) • channel-to-channel threshold spread • (σ =70e-no equalization) • (σ = 5e-with equalization) Input stage Voltage follower Vdd_ana 720 nA 435 nA 70 nA Uout_preamp C*= 6f Uout_comp Discr. ncap C=170fF gm=23u 5/0.24 UTHR_pixel sub_preamp (0.2V) Preamp_in 1fF Cpar ≈ 10 fF Ron = 30MΩ Ron = 100MΩ Tfb Vdd_ana 0.48/2.4 0.48/2.4 UTHR_common 6 nA 2nA 2.4/2.4 2.4/2.4 Baseline recovery Feedback TWEPP-09 V.Gromov 22/09/09 13

  14. Time-over-threshold measurements Ib = 1nA Uout,V 0.4 0.3 0.2 0.1 0 discharging Cfb= 1fF Qin=400e-… 28000e- Uout OPAMP Qin threshold Cpar =10fF ToT charging 0 1μ 2μ 3μ 4μ 5μ Time, sec ToT, ns • Features • wide dynamic range (up to 28ke-) • resolution σ = 200e- (27ns) • poor channel-to-channel uniformity (spread is 20%) 0.13ns / e- Qmax =28 000e- Qin, e- TWEPP-09 V.Gromov 22/09/09 14

  15. Discharge protection NO protection layer With protection layer InGrid InGrid UHV = - 400V UHV = - 400V 50μm CGR= 25pF SiNProt (7μm thick) CSP = 20fF Qdis High resistive protection layer Qdis Read-out chip 1.4cm x 1.4cm Read-out chip 1.4cm x 1.4cm Qdis= UHV●CGR = 10 000pC Qdis= UHV●CSP = 8pC SiNProt layer limits the size the discharge TWEPP-09 V.Gromov 22/09/09 15

  16. Protection device: Qdis= 8pC Standard NFET (W=1μm, L=0.24 μm) IMOS_channel in_preamp (Udc=+0.424V) GND GND n+ n+ p+ Idiode n-type inversion layer P-well Uin_preamp With protection • Features • small area (W=1μm, L=0.24μm) • low parasitic capacitance (1.3fF) • negligible leakage current (250pA) ← -1V (no damage of the MOSFET’s) No protection ← -7.5V (the MOSFET’s will be damaged) TWEPP-09 V.Gromov 22/09/09 16

  17. Conclusions • Gossipo-3 is a prototype of a Front-end Pixel Chip (0.13μm CMOS technology) for Read-out of Micro-Pattern Gas Detectors. • Every pixel is equipped a high resolution TDC (1.7ns) covering dynamic range up to 100us and a ToT counter to evaluate the charge deposit. • The chip can also operate in hit counting mode. • Gossipo-3 is taped-out for MPW production run (September 21). TWEPP-09 V.Gromov 22/09/09 17

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