A Complete Read-Out Chain for X-Ray Spectrometry

This paper presents a complete read-out chain for large arrays of X-ray detectors to be used for spectrometry applications in space. The system is fully integrated except for the X-ray detector. It basically consists of a front-end circuit for processing the detector signal, a Wilkinson A/D converter for the analog-to-digital conversion and the digital logic required to ensure the correct handshaking between all the blocks of the read-out chain. The system allows us to process the signal provided by the detector down to the final analog-to-digital conversion. All these functionalities are embedded in a single chip that will be bump-bonded to the matrix of X-ray detectors. The chip, designed in a 0.35 mum CMOS technology, achieves an input-referred noise of 34 e_rms ^-, consuming 0.9 mW from a 3.3 V power supply. The on-board A/D converter features 10 bits of resolution with a maximum conversion time of 210 mus. The INL and DNL of the whole read-out channel are equal to plusmn3.3 LSB and plusmn0.2 LSB, respectively.