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SamPic0: a 16-Channel, 10-GSPS TWDC Digitizer Chip for Picosecond Time Tagging

Abstract : SamPic0 is a Waveform and Time to Digital Converter (WTDC) multichannel chip providing outstanding time measurement capabilities. It makes use of the new AMS 0.18-m CMOS technology. One of its specificities stands in its capacity to directly measure the arrival time of fast analog signals without the need of any external discriminator. Each of its 16 channels associates a traditional DLL-based TDC providing a raw time based on a counter and a DLL with an ultra-fast 64-cell deep analogue memory ( bandwidth > 1.5 GHz, sampling frequency > 10GS/s) allowing fine timing extraction as well as other parameters of the pulse like charge, pulse width or rise-time. Each channel also integrates a discriminator that can self-trigger the channel independently or allow it to participate to a more complex trigger embedded on-chip. External trigger is also available. After triggering, analogue data is also digitized on-chip by a massively parallel low-power 11-bit ADC Wilkinson ADC running at 1.3 GHz and only data corresponding to a predetermined region of interest is then serially transferred towards the acquisition system. Dead-time is thus limited to 1.6 s for an 11-bit conversion and is as low as 400 ns for a 9-bit conversion which already provides an excellent time precision. Contrasting with the existing fast sampler chips usually designed for all-purpose applications and requiring external electronics to be used for performing accurate timing measurements, the SAMPIC0 chip presented here has been specifically designed for this type of application. Although the SAMPIC0 chip was originally thought as a technological demonstrator, its readout has been structured from the start for low dead-time applications and its design thus permits an easy integration in medium size acquisition systems. Such a set of boards and DAQ system has already been developed with the primary goal of evaluating the chip performances, but it is also usable to take data with detectors in a real environment. This setup, including a powerful software with an original interactive graphical interface, has permitted the characterization of the SAMPIC0 chip, and the measurements of its time resolution which is as good as 14 ps rms without any correction. This value is decreased in the range of 3 to 4 ps rms after a simple correction, itself based on a very simple calibration. This calibration remains very stable with time and can thus be stored on-board. The talk will present the new WTDC concept, the chip architecture, the existing set of boards and DAQ system and will give report of the latest measurements of the chip performances. It will also present the modifications and additions to the design of the second version of the chip, which should be submitted in the first half of 2014. In addition to a few corrections, these modifications mainly target the analog and noise performances, the improvement of the trigger logics and the reduction of the dead-time.
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http://hal.in2p3.fr/in2p3-00995680
Contributor : Sabine Starita <>
Submitted on : Friday, May 23, 2014 - 3:34:13 PM
Last modification on : Wednesday, September 16, 2020 - 5:43:22 PM

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  • HAL Id : in2p3-00995680, version 1

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D. Breton, E. Delagnes, H. Grabas, J. Maalmi, P. Rusquart, et al.. SamPic0: a 16-Channel, 10-GSPS TWDC Digitizer Chip for Picosecond Time Tagging. RT2014 - 19th Real-Time Conference, May 2014, Nara, Japan. ⟨in2p3-00995680⟩

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