A 16 channel discriminator VME board with enhanced triggering capabilities

Electronics and data acquisition systems used in small and large scale laboratories often have to handle analog signals with varying polarity, amplitude and duration which have to be digitized to be used as trigger signals to validate the acquired data. In the specific case of experiments dealing with ionizing radiation, ancillary particle detectors (for instance plastic scin-tillators or Resistive Plate Chambers) are used to trigger and select the impinging particles for the experiment. A novel approach using commercial LVDS line receivers as discriminator devices is presented. Such devices, with a proper calibration, can handle positive and negative analog signals in a wide dynamic range (from 20 mV to 800 mV signal amplitude). The clear advantages, with respect to conventional discriminator devices, are reduced costs, high reliability of a mature technology and the possibility of high integration scale. Moreover, commercial discriminator boards with positive input signal and a wide threshold swing are not available on the market. The present paper describes the design and characterization of a VME board capable to handle 16 differential or single-ended input channels. The output digital signals, available independently for each input, can be combined in the board into three independent trigger logic units which provide additional outputs for the end user.