A 0.8 μm CMOS pixel IC for low energy X-ray spectroscopy with on-chip detector

A charge sensitive readout chain has been developed for pixel applications with small die area and low power dissipation. The overall measured gain is 500 mV/fC; the ENC is 15.3e rms@15 fF; the power dissipation is 1.5 mW@3.3 V with 30 pF load capacitance; the active die area is 270 μm×270 μm. A detector has been integrated on the same substrate with the electronics. It consists of a 20 μm×20 μm diode, which is DC coupled to the input of the readout chain. The IC has been designed and fabricated in a 0.8 μm commercially available CMOS technology. A series of tests has been performed employing X-ray sources with energies from 2.3 to 3.3 keV. The experimental results are reported and the noise characteristics of the system are evaluated. With a FWHM of less than 300 eV in room temperature, low energy X-ray spectroscopy is clearly feasible using an integrated detector element in commercial CMOS technology