Low noise preamplifier ASIC for the PANDA EMC

For the electromagnetic calorimeter of the PANDA detector a preamplifier ASIC named APFEL (ASIC for Panda Front-end Electronics) has been developed at GSI. It is optimized for the readout of large area avalanche photodiodes (LAAPD) with a capacitance of 300 pF and an event rate of 350 kHz. The ASIC has two equivalent analog channels each consisting of a charge sensitive amplifier, a shaper stage and differential output drivers. For operating the ASIC in a wide temperature range programmable voltage references are implemented on chip. The characterization of the third ASIC iteration at a temperature of T = -20° C and a detector capacitance of 300 pF results in an equivalent noise charge of ENC = (0.62 ± 0.03) fC and a maximum input charge of 6.3 pC. Therefore a dynamic range of over 10 000 follows. The peaking time of the shaped signal was measured to t_p = (248 ± 3)ns. The event rate independent power consumption of one channel is P = (56.5 ± 0.5)mW.