OPTIMIZED DIGITAL FEATURE-EXTRACTION IN THE FERMI MICROSYSTEM

We describe the digital filter section of the FERMI readout microsyste m. The filter section, consisting of two separate filter blocks, extra cts the pulse amplitude and time information for the first-level trigg er process and performs a highly accurate energy measurement for highe r-level triggering and data readout purposes. An FIR-order statistic h ybrid filter structure is used to improve the amplitude extraction per formance. Using a training procedure the filters are optimized to prod uce a precise and accurate output in the presence of electronics and p ile-up noise, sample timing jitter and the superposition of high-energ y pulses. As the FERMI system resides inside the detector where access ibility is limited, the filter implementations are presented together with fault tolerance considerations. The filter section is modelled wi th the VHDL hardware descriptive language and the subsystems are furth er optimized to minimize the system latency and circuit area.