The model 755 logic unit contains four channels of four input logic with veto in a single width NIM module. Logic AND, OR, Majority logic, Fan-in/Fan-out, and anti-coincidence functions can be performed with this versatile module. All functions are direct coupled and operate to over 150 MHz with input overlap times as narrow as 1nSec.
Each channel has four logic inputs, an anti-coincidence input, a coincidence level switch, and five outputs with common width control. The inputs are enabled by connecting the input cable to the desired input, eliminating errors often occurring with switched inputs. The setting of the coincidence level switch then determines whether a logic OR, AND, or Majority logic function will produce an output.
After the inputs have satisfied the logic function desired, triggering of an updating regenerative stage produces a standardized output pulse, variable from 4nSec to 1µSec, independent of the input pulse shapes or overlap times. The updating feature ensures deadtimeless operation, while the double-pulse resolution is 6.5nSec for fast counting applications.
The outputs are the current source type with two pairs of negative bridged outputs and one complement for each channel. When only one output of a bridged pair is used, a double-amplitude NIM pulse (-32mA) is generated for driving long cables with narrow pulse widths. The outputs have transition times of typically 1nSec, and their shapes are virtually unaffected by the loading conditions of the other outputs.