Front-end electronic for the calice ECAL physics prototype

A 18-channel low-noise front-end chip has been designed and produced to read out the 1cm² silicon PIN diodes of the CALICE W-Si physics prototype calorimeter. Each channel includes a multi-gain low noise charge preamplifier followed by a bi-gain shaper and a track and hold device. A single output allows reading out every channel at 5 MHz through a multiplexer. Voltage swing is 2.5V with a 5% non-linearity. The measured dynamic range on a fixed gain is larger than 13 bits. The gain of the preamplifier can be tuned from 0.3V/pC to 5V/pC with 4 bits. The shaping is done by two fixed-gain shapers (gain 1 and gain 10). Output measured noise is 3000 e-with a detector capacitance of 100pF and a MIP around 42000 e-. Crosstalk is around 1%. 1000 chips have been produced to equip the physics prototype. Several version of PCB have been designed, taking into account the thickness constraint. A first version with the front-end chip outside the detector has been produced and has been running since January 2005 at DESY, exhibiting an overall MIP/noise ratio of 9. A new thinner version embedding the chip inside the calorimeter has been prototyped and is ready to go in test beam.