Readout electronics in large detector matrix for soft X-ray in medical applications

MACARENA is a full custom analog–digital CMOS integrated circuit (IC) designed for single X-ray photon detection for digital mammography. The IC is a complete front-end channel designed to be the main cell that will be used for a modular building of a large array of data acquisition channels. The channel consists of a low noise charge sensitive amplifier (CSA), a shaper, a discriminator and a 13 bit counter-shifter. The main characteristics of the IC are (1) channel power consumption of 80 μW; (2) minimum signal discriminated of about 400 electrons; (3) the equivalent input noise charge (E.N.C) at shaper output is 150e+3*Cd[pF] r.m.s; (4) compact design of a 13 bit asynchronous ripple counter reconfigurable in to a shift register and (5) single power supply. The front-end was designed to operate, with our specific Si matrix detector, in the photon energy range from 10 to 100 keV, the range of medical interest.