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Calorimeter upgrade meeting – CERN – April 15 th 2011

Progress on ICECAL chip test Upgrade of the front end electronics of the LHCb calorimeter. E. Picatoste , D. Gascón, A. Sanuy, Universitat de Barcelona Institut de Ciències del Cosmos ICC-UB. Calorimeter upgrade meeting – CERN – April 15 th 2011. Outline. New measurements setup

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Calorimeter upgrade meeting – CERN – April 15 th 2011

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  1. Progress on ICECAL chip test Upgrade of the front end electronics of the LHCb calorimeter E. Picatoste, D. Gascón, A. Sanuy, Universitat de Barcelona Institut de Ciències del Cosmos ICC-UB Calorimeter upgrade meeting – CERN – April 15th 2011

  2. Outline • New measurements setup • New blocks • Sample-and-Hold • Summary & news LHCb Upgrade

  3. New measurements setup • Attenuator: • Better linearity than AWG (<1%) • No need for timing corrections • WaveCatcher: • Better linearity than oscilloscope • PC: • Automatized system

  4. New measurements setup AWG PROBE ATTENUATOR WAVECATCHER

  5. Linearity measurements New linearity measurements started: Results show that a calibration of the amplifier+probe is required

  6. Residual Amplitude • Impact of the residual amplification in reset? • To be tested • Additional switches ? • Not needed according simulations • Few % error in the tail • Measure at 2 points after cycle with main signal: • Just after reset period (beginning of integration period) • End of integration period (effects of the tail of the signal) • Clipping is not perfect => small signal tail ? Measure residual effect 6

  7. Residual Amplitude • Impact of the residual amplification in reset: • Constant value of about 2% • To be tested on the other (11) chips and for each subchannel 7

  8. Residual Amplitude • Effect of the tail of the signal: • Caused by the signal tail; due to not perfect clipping • Measured 12% of the main signal for 1 subchannel of 1 chip • To be checked for the rest of chips • Dividing the integral of the residual signal by the one of the input signal result in 12-13% Qsignal/Qrresidual = 12-13% Qsignal Qresidual 8

  9. New blocks Prototyped in June AMS run: Low noise current amplifier: Basic schemes Integrator: High GBW fully differential OpAmp Could be used in other stages • To be tested in future runs: • Compensation of process variation of amplifier’s input impedance • Track and hold (if needed) • Analogue multiplexer • ADC driver • ADC needs to be characterized • Common blocks: • Clock generation • Biasing (CMOS band gap already exists) Ok, but need to add some tuneability

  10. Track-and-Hold Design example: 12-bit 125MHz Track-and-Hold Hold capacitor Tracking switch • Tracking phase: Qb = -CsVi • Bottom-plate off (before Mix) →Add fixed ΔQ2 • Mix off →Vbx remains ct →Q α Vix • Problems: • Fixed charge error • Fixed clock feedthrough error Bottom plate network to minimize non-linearities • C. Barth and A. Dhurka, “Design and Analysis of low power high speed Track-and-Hold circuits for 6 and 12-bit ADCs”, EE315 (VLSI Data Conversion Circuits) Project, Spring 2008 10

  11. Track-and-Hold OTA specifications • Slew rate: • Time allocated for slewing 1/8 TS • Output signal is 2V maximum => SR = 0.6 V/ns • DC gain: • Assume linear settling • If we require an accuracy ½ LSB => DC gain A0 > 80 dB • As A0 only affects linearly, A0 can be lower and the effect would be calibrated afterwards. • Gain bandwidth product: • GBW = 190 MHz Reuse/adapt existent OTA 11

  12. Summary • New setup is ready to finish the measurements of the input stage (preamp+integrator) • Principle is ok • Good previous results with 12 chips statistics • Need to calibrate new probe • Need to study the effect of bias (op. paint) variation • Impact of the residual amplification in reset? • Additional switches ? • Not needed according simulations • Few % error in the tail • Agreement with first results • Tests to be completed • Characterization of individual blocks to be completed • Preamplifier: • Linear input range is almost 4 mA peak current • Could tolerate unclipped signal • Additional gain trimming should be foreseen • Fully differential amplifier: TbD

  13. Plans Plans for 2011 Test and design until Q3 2011 Prepare a prototype for a run in June 2011 including Track-and-Hold Submit a prototype with few complete channels in Q4 2011 Goal of submitting a complete channel in Q4 2011 should be preserved And for 2012, if everything is ok… Test beam ? Radiation tests? Long term: technology obsolescence… AMS 0.35 um is a “mature” techno We asked to Europractice: 5 years are “guaranteed” Low volume productions are scheduled Production (engineering run) is safe But for desin (MPW runs) we should not relax

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