VX1720

Overview

The VX1720 is a 1-unit wide VME64X 6U module housing a 8 Channel 12 bit 250 MS/s Flash ADC Waveform Digitizer and featuring 2 Vpp single ended input dynamics.
The DC offset adjustment (range ±1 V) by programmable 16bit DACs (one for each channel) on single ended input versions allows a right sampling of a bipolar (Vin = ±1 V) up to a full positive (Vin = 0 ÷ +2 V) or negative (Vin = 0 ÷ -2 V) analog input swing without losing dynamic resolution.
The module features front panel Clock Input and Output as well as a PLL for clock synthesis from internal/external references. The data stream is continuously written in a circular memory buffer. When the trigger occurs, the FPGA writes further N samples for the post trigger and freezes the buffer that can be read either by VMEbus or Optical Link. The acquisition can continue without dead time in a new buffer.

Each channel has a SRAM Multi-Event Buffer divisible into 1 ÷ 1024 buffers of programmable size. Two sizes of the channel digital memory are available by ordering options: 1.25 MS/ch (mod. VX1720E) and 10 MS/ch (mod. VX1720G). “Zero suppression” and “data reduction” algorithms allow substantial savings in data amount readout and processing, rejecting samples smaller than programmable threshold. VX1720 supports multi-board synchronization allowing all ADCs to be synchronized to a common clock source and ensuring Trigger time stamp alignment. Once synchronized, all data will be aligned and coherent across multiple VX1720 boards.
The trigger signal can be provided externally via the front panel Trigger Input as well as via the software, but it can also be generated internally thanks to threshold self-trigger capability. The trigger from one board can be propagated to the other boards through the front panel Trigger Output.

An Analog Output is available with four operating modes supported:

• Waveform Generator: 1 Vpp ramp generator
• Majority: output signal is proportional to the number of ch. under/over threshold (1 step = 125 mV)
• Buffer Occupancy: output signal is proportional to the Multi Event Buffer Occupancy: 1 buffer ~ 1 mV
• Voltage level: output signal is a programmable voltage level

VX1720 houses VME (VME64X compliant) and Optical Link interfaces. The VME interface allows data transfers of 60 MB/s (MBLT64), 100 MB/s (2eVME), 160 MB/s (2eSST). The Optical Link supports transfer rate of 80 MB/s and offers Daisy chain capability. Therefore, it is possible to connect up to 8/32 ADC modules to a single Optical Link controller (Mod. A2818/A3818).

Software available (Windows and Linux):
CAEN provides drivers for all the different types of physical communication channels, a set of C and LabView libraries (CAENComm and CAENDigitizer), demo applications and utilities:

• CAENSCOPE: fully graphical program that implements a simple oscilloscope.
• CAENUpgrader: tool that allows the user to update the firmware of the digitizers, change the PLL settings, load, when requested, the license for the pay firmware and other utilities.
• CAEN WaveDump: software console application that can be used to configure and readout event data from any model of the CAEN digitizer family and save the data into a memory buffer allocated for this purpose.

CAEN provides also for this model Digital Pulse Processing firmware for Physics Applications. This feature allows to perform on-line processing on detector signal directly digitized:

• DPP-PSD Digital Pulse Processing for Pulse Shape Discrimination
  x720(*) and x751 digitizers running DPP-PSD firmware accept signals directly from the detector and implement a digital replacement of dual gate QDC, discriminator and gate generator.

(*) DPP-CI firmware and DPP-CI Control Software are no longer supported. To perform Charge Integration please refer to the DPP-PSD firmware and software

The VX1720 fits in the single-slot CAEN VME64X u-crate, which allows you to convert the VME digitizer into a desktop board for lab tests.