1. Technical status of the Gossipo-3 : starting point for the design of the Timepix-2 March 10, 2010. Vladimir Gromov NIKHEF, Amsterdam, the Netherlands

2. Timepix-2 V.Gromov210/03/10 Micro-pattern gas detectors: layout and features - particle track image (projection) - 3D track reconstruction - - no sensor leakage current compensation - low parasitic capacitance (less than 10fF) - micro-discharges in avalanche gap Cluster3 Cathode (drift) plane Gas Amplification Structure Cluster2 Cluster1 Readout chip 1mm …1m → Drift gap 400V 50um → Avalanche gap Gas-avalanche detector combining a gas layer as signal generator with a CMOS readout pixel array Front-end circuit Cpar

3. Timepix-2 V.Gromov310/03/10 Gossipo-3: functionality and 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

4. Timepix-2 V.Gromov410/03/10 Gossipo-3/Gossipo-2: main specifications 2007: GOSSIPO-2 - technology: 0.13μm CMOS - array: 16 x 16, 256 pixels - pixel: 55 um x 55 um - active area: 0.88mm 2 - event clock: 40MHz - high resolution TDC-per-pixel architecture (bin=1.8 ns) - range: 350ns (4-bits @ 25ns) 2009: GOSSIPO-3 - technology: 0.13μm CMOS - pixel: 60μm x 60μm - event clock: 40MHz - accuracy (bin size): 1.73ns - range: 102μs (12-bits @ 25ns) (for Large-Volume TPC) - 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/cm 2 (3μW/ch) GOSSIPO-2 GOSSIPO-3

5. Timepix-2 V.Gromov510/03/10 High resolution TDC-per-pixel with local ring oscillator Hit signal Local oscillator output (F fast = 640MHz) Start Stop Clock signal (F slow = 40MHz). Trigger signal Stop N slow N fast Time = N slow / freq slow + N fast /freq fast Start Stop Local oscillator Pixel_1 Hit 40MHz Clock Bus Out Power ≈ Hit_Rate ● 6 μW / MHz per channel → 0.16 μW @ 27.2KHz

6. On-pixel ring oscillator

7. Timepix-2 V.Gromov710/03/10 On-pixel ring oscillator :basic limitations NAND EN OUT Delay = T fast /2 = Function (Temp, Vdd) EN T fast (1.72 ns) OUT - 12% / 100mV 2% / 10 ◦ C Channel-to-channel statistical spread is 4% VDD effectTEMP effect 0ns…T slow (25 ns) 0…15 (4-bit TDC) 2.2 2.1 2 1.9 1.8 1.7 1.6 1.05 1.1 1.15 1.2 1.25 1.3 Power supply voltage, Volts 0 20 40 60 80 100 2.2 2.1 2 1.9 1.8 1.7 Temperature, ◦ C T fast,ns

8. Timepix-2 V.Gromov810/03/10 On-pixel ring oscillator : reproducibility ∆t max = 0.5ns (accumulated) Pixel-to-pixel mismatchPixel-to-pixel mismatch σ(∆T fast /T fast ) ≈ 2% ● (N●W ● L) -0.5 Monte Carlo simulations. vdd_osc Nominal situation Upper limitLow limit 0.61 V 1.72 ns 0.76 V 1.73 ns 1.13 ns2.26ns 1.1 V 1.72 ns T fast =1.73ns Process variationProcess variation clock period =25ns

9. Timepix-2 V.Gromov910/03/10 On-pixel ring oscillator : frequency calibration - tunes oscillation frequency - power supply ripple rejection - temperature compensation Tune-based calibration (Gossipo-3)Tune-based calibration (Gossipo-3) Opamp Off-chip cap 10μF 4bit DAC Bandgap Current Reference with Temp. Gradient Vdd=1.2V 1.14k 2k U vdd_osc (0.6V…1.1V) Uref PLL-based calibrationPLL-based calibration - automatic process, voltage and temperature compensation Replica of the on-pixel ring oscillator Voltage regulator (LDO) LDO U vdd_osc (0.6V…1.1V)

10. Timepix-2 V.Gromov1010/03/10 Gossipo-3: top level schematic

11. Timepix-2 V.Gromov1110/03/10 Gossipo-3: the pixel LFSR = Counters (data taking) or LFSR = Shift registers (data read-out) Control signals - Clock - TRIGGER (common stop) - TOKEN - RESET Preamp Discr. control Local fast oscillator (600MHz) Local fast oscillator (600MHz) 4 bit Fast counter 8 bit ToT counter 12 bit Slow counter 4 bit Pixel configuration Memory Threshold DAC pad -Threshold - Mask Time / Counting HIT oscillator Logic: counters & control Preamp & comparator DAC Block diagram of the pixelBlock diagram of the pixelLayout of the pixelLayout of the pixel

12. Timepix-2 V.Gromov1210/03/10 Gossipo-3: operation in TIME mode Data taking phase (LFSR = Counter) Data read-out Phase (LFSR = Shift Registers) Clock (40MHz) Counter Fast Counter ToT Counter Slow Reset Preamp_out Hit (asynchronous) Trigger Token ToT State diagram

13. 0 20 Time, ns 40 60 80 threshold = 5●σ noise =350 e - Signal = 2400 e - time jitter / internal delay (TtT) ≈ 8 ns time jitter / internal delay (TtT) ≈ 3 ns time jitter / internal delay (TtT) = rise_time ● 5σ n / signal size Timepix-2 V.Gromov1310/03/10 Front-end circuit for high resolution time measurements Preamplifier Signal = 800 e - High signal-to-noise ratio Fast signal fast detector charge collection time (∆t det ) fast detector charge collection time (∆t det ) fast δ- pulse response → output signal rise time ≈ ∆t det fast δ- pulse response → output signal rise time ≈ ∆t det Time resolution

14. threshold Timepix-2 V.Gromov1410/03/10 Comparator Front-end circuit for high resolution time measurements Input signals Output signals 1000 Threshold =350 e - Signal size, electrons Comparator delay slow circuit response → low power 2000 30004000 ∆t min fast ∆t min slow Comparator delay ∆t min depends on the value of the tail current (I tail ) and therefore ∆t min is temperature dependent ∆t min is power supply voltage dependent ∆t min varies from channel-to-channel High signal-to-threshold ratio Fast comparator response Time resolution fast circuit response → medium power

15. Timepix-2 V.Gromov1510/03/10 Gossipo-3: front-end circuit Time Uin Uin + 70mV Uin + Qin / Cfb -Time ● Isat Tfb /Cfb exp[-Time/(Cfb ● Ron Tfb )] Uout Tfb in saturationTfb in triode - no leakage compensation - constant current feedback (1nA) - high gain (1mV / fF) - 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 C par ≈ 10 fF Tfb Cfb =Cds+Cdg+Cdb+Cdj ≈ 1 fF Input pad (22μm x 22μm) OPAMP Discharge protection Ib = 6nA 2.4/2.4 0.48/2.4 U out_preamp 2nA U THR_common Vdd_ana 2.4/2.4 0.48/2.4 U THR_pixel Discr. Baseline recovery U out_discri Ron = 100MΩ

16. I b =1 nA V b2 V b1 Output Input C par ≈ 30 fF C fb = 1 fF Features Based on the F.Krummenacher’s scheme - parasitic capacitance at the input C par ≈ 30 fF - low power consumption (2 µW). - pulse response rise-time is 20 ns - low noise (σ n =70 e - ENC) C in ∆V OPAMP Signal = 600 e - Signal = 2000 e - Preamplifier Timepix-2 V.Gromov1610/03/10 Gossipo-2: preamplifier !!! The DC feedback !!! Not operational channels (15 % - 30 %)

17. Timepix-2 V.Gromov1710/03/10 Timepix-2: design environment CERN distributed CMOS8RF-DM (3-2-3 BEOL) Mixed Signal Kit, V1.6.0.3DM 3 thin, 2 thick, 3 RF metal