C. Beigbeder, D. Breton, T. Caceres, P. Cros, A. Hrisoho, V. Tocut, K.Truong
Laboratoire de l'Accelerateur Lineaire BP 34 - 91898 ORSAY cedex - France
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The electronics for the electromagnetic and hadronic calorimeters of 
LHCb is under design. There are 6000 channels to readout in the Ecal and 1500
in the Hcal. The goal is to measure the energy of the particles with a
precision of 12 bits while avoiding any source of pile-up due to apparatus.
        Therefore, we perform a clipping of the photomultiplier output pulse 
after 10ns to avoid detector pile-up (what lets 60% of the charge useful) and 
an original shaping which avoids any electronics pile-up. The latter first
consists in the integration of the input signal what offers a plateau of 7 to 8
ns to the ADC sample and hold for conversion. The reset of the integrator capa-
citance is performed by the reception 25 ns later of the same signal but
inverted. A delay line is used for this purpose and the both inputs of the
amplifier are used for the subtraction.
        These functionnalities have been integrated in a four channel chip in
AMS 0.8u BiCMOS technology. The first prototypes have prooved the good
feasability of the chosen principles. The conversion is performed by a 
40MHz/12bit ADC. 
        These circuits are implemented on a 9U 32 channel front-end board. This
board offers all the functionnalities including pedestal subtraction, look-up
tables, level 0 latency pipelines, level 0 derandomizer and level 1 latency
fifo. It should also include the first stages of processing of the first level
calorimeter trigger. Access to the board is performed by a 10Mbit/s serial bus
which is distributed on the backplane. Two other boards are sitted in the same
crate, one for driving the serial bus and the TTC signals, and the other for 
the level 1 derandomizer and data formatter. There is still place available for
the potential other trigger boards.
        A special care has been taken in the testability of all the elements. 
Every analog input can thus be pulsed at a fixed level to check functionnality,
and bidirectionnal access to every main step of the digital chain is provided.
        A 16 channel 6U prototype board has been designed and will be used in
testbeam at CERN during this summer. This board includes all the 
functionnalities excepted the trigger part.
        The first results will be presented if available at the time of the
conference.
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The electronics for the electromagnetic and hadronic calorimeters of LHCb is under design. The 32 channel front-end board offers the complete front-end and readout electronics for every channel including original shaping, 12bit-40MHz ADC, digital filtering and latency for level 0 and level 1  triggers. The clipped PM input signal is integrated within 25ns, but also delayed then subtracted to itself 25ns later what allows performant pile up independance. This board also includes the first processing levels of the level 0 calorimeter trigger.  A 16 channel prototype board has been designed and used at CERN in  test beam last summer.
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