Speaker
Mr
sabyasachi chattopadhyay
(Inter University Centre for Astronomy and Astrophysics, Pune, India)
Description
IUCAA Digtial Sampling Array Controller (IDSAC) is a generic CCD Controller which is flexible and
powerful enough to control a wide variety of CCDs and CMOS detectors used for ground based astronomy. It
has a fully scalable architecture, which can control multiple CCDs and can be easily expanded. The controller
has a modular backplane architecture consists of Single Board Controller Cards (SBCs) and can control a
mosaic or independent of 5 CCDs. Each Single Board Controller (SBC) has all the resources to a run Single
large format CCD having up to four outputs. All SBCs are identical and are easily interchangeable without any
reconfiguration. A four channel video processor can process up to four output CCDs with or without dummy
output at 1Mpixels/Sec/Channel with 16 bit resolution. Each SBC will have USB 2.0 interface which will be
connected to a separate computer via USB to Fiber converters. The SBC uses a reconfigurable hardware
(FPGA) as a Master Controller. The best feature of IDSAC is it uses the technique of Digital Correlated
Double Sampling(DCDS). It is known that CCD video output is dominated by thermal KTC noise contributed
from the summing well capacitor of the CCD output circuitry. To eliminate thermal KTC noise Correlated
Double Sampling (CDS) is a very standard technique. CDS performed in Digital domain (DCDS) has several
advantages over its analog counterpart, such as - less electronics, faster readout and easier post processing. It is
also flexible with sampling rate and pixel throughput while maintaining the core circuit topology intact. The
noise characterization of the IDSAC CDS signal chain has been performed by analytical modelling, software
simulation and practical measurements. Various types of noise such as white, pink, power supply, bias etc. has
been considered while creating a analytical noise model tool to predict noise of a controller system like
IDSAC. Standard test bench softwares like Pspice and Multisim are used to simulate the noise performance
while several tests are performed to measure the actual noise of IDSAC.The theoretical calculation matches
very well with component level simulation as well as practical measurements within 10% accuracy.
Primary author
Mr
sabyasachi chattopadhyay
(Inter University Centre for Astronomy and Astrophysics, Pune, India)