A Programmable Analogue Front-End ASIC for Gas Micro-Strip Detectors having a wide range of Input Capacitance

The FREDA ASIC is designed as a performance upgrade for the front-end electronics of the ´HOT´ series gas micro strip detectors. These detectors have 512 channels each having different capacitance ranging from 2 pF-80 pF. FREDA is a 16 channel ASIC each of which consists of a preamplifier, a programmable CR-RC shaper, a programmable gain amplifier and an output buffer. The charge preamplifier contains a leakage current compensation circuit to avoid voltage offset due to leakage current. The CR-RC shaper has 7 programmable peaking time settings from 50 ns-240 ns. The programmable gain amplifier has 4 gain settings of 1, 2, 4 and 8. This ASIC has been designed using a 0.35 mum CMOS process. The ASIC architecture and generation are described including simulated and measured results.