Effect of technology on the input transistor selection criteria of a low noise preamplifier

An analysis of a preamplifier noise behaviour, of a low-energy X-rays strip detector for space applications, is presented. The ratio of equivalent thermal noise (enc/sub th/) to enc/sub 1/f/ is defined as the noise comparison ratio (NCR) and is used as the preamplifier input transistor selection criterion. The effect of low-noise preamplifier CMOS technology on noise minimization is thoroughly examined. The preamplifier was designed in AMS 0.6/spl mu/m process, with NMOS and PMOS input MOSFET, and in DMILL 0.8/spl mu/m, with NMOS input MOSFET. Analysis is supported by simulation results, which confirm that the selection of the preamplifier input transistor, for a given shaper, is depended on the noise parameters of the used technology.