Low noise high-speed X-ray readout IC for imaging applications

We present a mixed-signal, continuously sensitive, self-triggered IC designed for X-ray imaging applications. Both bipolar and CMOS devices were employed in order to achieve the speed and noise requirements associated with the particular application. Phenomena related to the submicron nature of the devices used have been also taken into consideration. The circuit is optimized to operate with a 3 pF Si-microstrip detector and it exhibits an equivalent noise charge of 225e− rms with a slope of 45e−/pF. The peaking time of the pulse at the output of the analog part is 28 ns and the circuit recovers to the baseline within 600 ns. Moreover, it has the ability of handling either positive or negative current pulses originating from the detector. The IC power consumption is 4.5 mW per channel and the chip was fabricated using a 0.8 μm BiCMOS technology.