<title>STIS ASIC charge-amp and voltage discriminator for MAMA detector readout</title>

Abstract

The continuing effort to improve detectors for low light applications has resulted in the development of imaging photon counting detectors. One such device is the MAMA (Multi- Anode Microchannel Array) detector fabricated by Ball Aerospace. This paper provides a brief overview of the STIS (Space Telescope Imaging Spectrograph) MAMA detector and a detailed description of the analog signal processing electronics. The analog signal processing circuit is built using two unique Ball Aerospace and Communications Group (BACG) designed ASICs (application specific integrated circuits). Each MAMA detector analog signal processing channel uses a pair of the ASICs. The first is a charge to voltage amplifier and the second a voltage discriminator. The amplifier has lower noise and higher speed than previous BACG designs. Its first stage gain bandwidth is 10 GHz with an equivalent input noise voltage of about 1 nV per root hertz. It has a single ended input and differential output to drive the voltage discriminator. The voltage discriminator ASIC has differential input and single ended, CMOS compatible, output. The system has a 120 ns pulse pair resolution with 21 ns amplitude dependent timing uncertainty. Calculated false event rate, for prototype devices, is 1 count in 107 sec with 100 pF detector capacitance and a 20,000 electron threshold. Counting rates greater than 1 million per second per channel can be accommodated. Both ASICs have much lower power consumption than previous discrete designs. The ASIC process used allows the fabrication of extremely robust devices while reducing the total number of parts.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.