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:
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
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 200000 strip lines Sampling frequency 40 MHz 1 MHz accepted triggers; no dead time if readout < 900 ns per event Decay distance resolution 120 m
10/09/2002IWoRID; Niels van Bakel4 Silicon strip detector Detector capacitance 5-30 pF Yearly radiation dose at 8 mm ~1 10 14 [1 MeV neutrons/cm 2 ] 300 (200) m thick 40-60 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
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
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
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
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
10/09/2002IWoRID; Niels van Bakel9 ENC behaviour of the new Beetle front end (measured on a test chip): 449 e - + 46.8 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 22000 electrons ENC measurements
10/09/2002IWoRID; Niels van Bakel10 Pulse shape Measured 15 ns rise time 20 % spillover HSPICE calculated pulse (solid line)
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
10/09/2002IWoRID; Niels van Bakel12 Preliminary Testbeam results S strip /N strip = 13.3 S cluster /N strip = 15.3 17.5 ns rise time 21.3 % spill over
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)
10/09/2002IWoRID; Niels van Bakel17 Analogue readout?
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?