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10/09/2002IWoRID; Niels van Bakel1 A collaboration between the ASIC-lab Heidelberg, NIKHEF Amsterdam and the University of Oxford Beetle; a front-end chip.

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Presentation on theme: "10/09/2002IWoRID; Niels van Bakel1 A collaboration between the ASIC-lab Heidelberg, NIKHEF Amsterdam and the University of Oxford Beetle; a front-end chip."— Presentation transcript:

1 10/09/2002IWoRID; Niels van Bakel1 A collaboration between the ASIC-lab Heidelberg, NIKHEF Amsterdam and the University of Oxford Beetle; a front-end chip for LHCb VELO ASIC lab Heidelberg

2 10/09/2002IWoRID; Niels van Bakel2 Outline 25 stations (50 Si planes) Vertex detector Silicon strip detectors Beetle architecture Radiation hardness Measured characteristics Conclusions

3 10/09/2002IWoRID; Niels van Bakel3 Required S/N > 14 (10 pF load) Power consumption < 6 mW/channel Peaking time  25 ns Pulse spill-over < 30 % after 25 ns Dynamic range ± 10 MIP The Vertex detector Provide production and decay vertex information Detector resolution ~8  m strip lines Sampling frequency 40 MHz 1 MHz accepted triggers; no dead time if readout < 900 ns per event Decay distance resolution  120  m

4 10/09/2002IWoRID; Niels van Bakel4 Silicon strip detector Detector capacitance 5-30 pF Yearly radiation dose at 8 mm ~1  [1 MeV neutrons/cm 2 ] 300 (200)  m thick  m inter strip distance 1 MIP creates ~22000 electrons LHCb requirements depend on efficiency, technical limits, costs 5 cm Energy loss distribution obeys a Landau function Non ionizing energy loss is expected to be the major source of radiation damage of the Silicon detector Fully depleted

5 10/09/2002IWoRID; Niels van Bakel5 Beetle architecture Readout via 2 m twisted-pair cable, repeater card preampshaper Pipeline 128  186 pipeline readout multiplexer 32  4 test channel 128 channels dummy channel Multi event buffer

6 10/09/2002IWoRID; Niels van Bakel6 Beetle layout Dimensions 6.1 mm  5.5 mm Pitch input pads 41.2  m Positive supply 2.5 V Analog output driver ~ 50 mV/MIP No dead channels allowed < 0.1 % dead pipeline cells pipeline I2C pipeline readout control front-end amplifiers 128 analogue inputs pipeline readout amplifiers multiplexers 4 outputs

7 10/09/2002IWoRID; Niels van Bakel7 Radiation hard design Tolerable irradiation dose > 10 Mrad in 5 years Field oxide Leakage current Gate oxide Obtain radiation hardness with: T ox < 10 nm : tunneling decreases the trapped ions in the gate-oxide Enclosed nMOS prevents large leakage currents Guardrings around nMOS Single event upset (SEU) triggered by single particles; tests needed Control logic protected by SEU: use triple redundant flip-flops with majority encoding

8 10/09/2002IWoRID; Niels van Bakel8 Beetle1.1 showed full functionality up to 30 Mrad (15 LHCb years): full trigger / readout functionality full slow control functionality performance degradations are small Radiation tests (TID) time [ns] V out [V] Test with X-ray facility at CERN Total ionizing dose results in gate bias voltage shifts

9 10/09/2002IWoRID; Niels van Bakel9 ENC behaviour of the new Beetle front end (measured on a test chip): 449 e e - /pF The channel thermal noise dominates the noise for an input transistor with a large area: 45.3 e - /pF (calculated) 1 MIP in the detector generates electrons ENC measurements

10 10/09/2002IWoRID; Niels van Bakel10 Pulse shape Measured 15 ns rise time 20 % spillover HSPICE calculated pulse (solid line)

11 10/09/2002IWoRID; Niels van Bakel11 The Beetle in a Testbeam 40 mm 80 mm 130 mm Beam telescope R and Phi Beetle Track Scintillator trigger Tracks used 40 MHz sampling rate Two Beetle chips bonded Aligned with ~30  m precision

12 10/09/2002IWoRID; Niels van Bakel12 Preliminary Testbeam results S strip /N strip = 13.3 S cluster /N strip = ns rise time 21.3 % spill over

13 10/09/2002IWoRID; Niels van Bakel13 Conclusions and outlook The Beetle1.1 fulfills the LHCb requirements: rise time spillover S/N sample frequency radiation hardness Additional data with 16 Beetle1.1 chips on a VELO Beetle hybrid bonded to a silicon detector Improved Beetle1.2 available since July (see LEB) Beetle also considered for the Inner tracker, RICH detector and the pile-up veto detector (LHCb)

14 10/09/2002IWoRID; Niels van Bakel14 Residuals

15 10/09/2002IWoRID; Niels van Bakel15 Landau?

16 10/09/2002IWoRID; Niels van Bakel16 RF tests?

17 10/09/2002IWoRID; Niels van Bakel17 Analogue readout?

18 10/09/2002IWoRID; Niels van Bakel18 track mode pulse mode left:- signal pulse shape - comparator output right: - binary readout (4 consecutive BX) Comparator output level shifter is too slow  causes spill-over to the second BX  Beetle 1.2: has now an output buffer Comparator?


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