Noise characterization of IUCAA digital sampling array controller

Sabyasachi Chattopadhyay, A. N. Ramaprakash, Bhushan Joshi, Pravinkumar A. Chordia, Mahesh P. Burse, Kalpesh Chillal, Sakya Sinha, Sujit P. Punnadi, Ketan Rikame, Sungwook E. Hong, Dhruv Paranjpye, Haeun Chung, Changbom Park, Amitesh Omar

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The IUCAA digital sampling array controller (IDSAC) is a flexible and generic yet powerful CCD controller that can handle a wide range of scientific detectors. Based on an easily scalable modular backplane architecture consisting of single board controllers (SBC), IDSAC can control large detector arrays and mosaics. Each of the SBCs offers the full functionality required to control a CCD independently. The SBCs can be cold swapped without the need to reconfigure them. IDSAC is also available in a backplane-less architecture. Each SBC can handle data from up to four video channels with or without dummy outputs at speeds up to 500-kilo pixels per second (kPPS) per channel with a resolution of 16 bits. Communication with a Linux-based host computer is through a USB3.0 interface, with the option of using copper or optical fibers. A field programmable gate array (FPGA) is used as the master controller in each SBC, which allows great flexibility in optimizing performance by adjusting gain, timing signals, bias levels, etc., using user-editable configuration files without altering the circuit topology. Elimination of thermal kTC noise is achieved via digital correlated double sampling (DCDS). The number of digital samples per pixel (for both reset and signal levels) is user configurable. We present the results of noise performance characterization of IDSAC through simulation, theoretical modeling, and actual measurements. The contribution of different types of noise sources is modeled using a tool to predict noise of a generic DCDS signal chain analytically. The analytical model predicts the net input referenced noise of the signal chain to be 5 electrons for 200-k pixels/s per channel readout rate with three samples per pixel. Using a cryogenic test setup in the lab, the noise is measured to be 5.4 e (24.3 μV), for the same readout configuration. With a better-optimized configuration of 500-kPPS readout rate, the measured noise is down to 3.8 electrons RMS (17 μV), with three samples per interval.

Original languageEnglish (US)
Article number036002
JournalJournal of Astronomical Telescopes, Instruments, and Systems
Issue number3
StatePublished - Jul 1 2018
Externally publishedYes


  • Detector arrays
  • Digital processing
  • Image analysis
  • Image processing
  • Noise

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Control and Systems Engineering
  • Instrumentation
  • Astronomy and Astrophysics
  • Mechanical Engineering
  • Space and Planetary Science


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