Development of X-ray CCD camera system with high readout rate using ASIC

Abstract

We report on the development of an X-ray charge-coupled device (CCD) camera system with high readout rate using application-specific integrated circuit (ASIC) and Camera Link standard. The distinctive Δ Σ type analog-to-digital converter is introduced into the chip to achieve effective noise shaping and to obtain a high resolution with relatively simple circuits. The unit test proved moderately low equivalent input noise of 70 μ V with a high readout pixel rate of 625 kHz, while the entire chip consumes only 100 mW. The Camera Link standard was applied for the connectivity between the camera system and frame grabbers. In the initial test of the whole system, we adopted a P-channel CCD with a thick depletion layer developed for X-ray CCD camera onboard the next Japanese X-ray astronomical satellite. The characteristic X-rays from 109Cd were successfully read out resulting in the energy resolution of 379 ( ± 7 ) eV (FWHM) @22.1 keV, that is, Δ E / E = 1.7 % with a readout rate of 44 kHz.