Back-end Readout Electronics for Hyper Suprime-Cam

We have developed the back-end readout electronics (BEE) for Hyper Suprime-Cam (HSC). HSC is the next generation wide-field camera to be mounted on the 8.2-meter diameter Subaru Telescope in Hawaii. It employs 116 pieces of 2k x 4k Charge Coupled Devices (CCDs) to cover a 1.5 degrees diameter field of view. The electronics system for HSC can be divided into two parts: the front-end electronics (FEE) in which analog signals from CCDs are processed and the BEE which is a digital component of the readout electronics. The BEE sends a readout clock to the CCD and FEE, receives the image data from the FEE and sends them to the data acquisition computers. The electronics are required to read the CCDs at the rate of 243k pixel/sec/CCDoutput while suppressing the readout noise smaller than about 4 electrons, so that the 2.3G byte of an image data can be read within about 10 seconds. We designed the BEE as 3U Euro-card system with seven slots (140 mm x 180 mm x 130 mm) to achieve all the requirements for HSC. The maximum readout speed was 265k pixel/sec/CCDoutput and the readout noise was smaller than 3 electrons, including the clock jitter noise of 0.1 electrons. We concluded that our back-end readout electronics have sufficient performance for HSC.