A bipolar, semi-gaussian pulse shaping amplifier based on transconductance-C continuous time filters for use in a high resolution, small animal x-ray CT system

A new bipolar, semi-gaussian pulse shaping amplifier using transconductance-C (G_m-C) filters has been developed for use with the Oak Ridge National Laboratory (ORNL) MicroCAT small animal x-ray CT imaging system. The MicroCAT system employs Cadmium Zinc Telluride (CZT), a relatively new semiconductor detector material. The pulse shaping amplifier is based on a G_m-C filter topology and has adjustable gain, tunable filter time constants and quality factors as well as a differential signal path. The transconductor circuit design is also presented with emphasis placed upon the noise and linearity of the circuit. The architecture and experimental results for the prototype pulse shaping amplifier are also presented. The prototype was fabricated in the 1.2μ AMI NWELL CMOS process through the MOSIS program.