A Complete Read-Out Channel With Embedded Wilkinson A/D Converter for X-Ray Spectrometry

This paper presents a complete read-out channel suitable 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 channel. 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, in its final version, will be bump-bonded to the matrix of X-ray detectors. The chip, designed in a 0.35 m CMOS technology, achieves an inputreferred 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 s. The INL and DNL of the whole read-out channel are equal to 3.3 LSB and 0.2 LSB, respectively.