N6742

Overview

The CAEN Mod. N6742 is a NIM module housing 16+1 Channel 12 bit 5 GS/s Switched Capacitor Digitizer. The input dynamic range is 1 Vpp on single-ended MCX coaxial connectors (16-bit DAC on each channel to control the DC Offset).

The digitizer is based on the Switched Capacitor Array DRS4 chip (Domino Ring Sampler). This technology relies on a series of 1024 capacitors (analog memory) in which the analog input signal is continuously sampled in a circular way. The sampling frequency is 5 GHz by default and it can be programmed to 2.5 GHz, 1 GHz, and 750 MHz. The analog to digital conversion is not simultaneous with the chip sampling phase, and it starts as soon as the trigger condition is met, thus producing a dead time of 110 μs in case only the analog inputs are digitized, 181 μs when also the fast trigger TR0 is digitized. When the trigger stops the DRS4 chip sampling (holding phase), the analog memory buffer is frozen, and the cell content is made available to the 12 bit ADC for the digital conversion. The digital memory allows to store subsequent events, even if the readout is not yet started. Moreover, since the digital memory buffers work like FIFOs, the readout activity from USB or Optical Link does not affect write operations of subsequent events.

The available trigger sources are:

• External Trigger, trigger on TRG-IN connector, common to all enabled groups.
• Fast (Low Latency) Local Trigger, trigger on TR0 connector, common to all enabled groups. This mode is called “Fast” or “Low Latency” since the trigger latency to hold the DRS4 is reduced with respect to the external trigger. This trigger mode is convenient for high precision timing measurements, since the TR0 can be digitized and reported in the output data to be used as time reference.
• Self-trigger, common to all enabled groups. For each group is possible to select combination of channels (logic OR) that provide a trigger whenever the input crosses the threshold. This mode cannot be used at 5 GHz due to the trigger latency.

The module features the front panel CLK IN connector and an internal PLL for clock synthesis from internal/external references. The module is available with digital memory sizes of 128 event/ch or 1024 event/ch.

N6742 houses USB 2.0 and Optical Link interfaces. USB 2.0 allows data transfers up to 30 MB/s. 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:

• 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.

Software for N6742 running Waveform Recording Firmware:

• 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.