The LRS Model 322 is a general purpose high speed logic unit whose extremely flexible design suits it for a wide range of applications both in particle physics and low energy nuclear physics. The inputs of the Model 322 are direct-coupled and fully overload protected; the unit may therefore be used with input signals from any of a very wide range of signal sources, of amplitudes from seven hundred millivolts to one hundred volts, of any rise time from sub-nanosecond up without limit, and of any duration from a few nanoseconds up without limit. While the unit is typically used with standardized logic signals from other high speed modules, its input characteristics by no means restricts it it to these signals, and it may be used successfully with unshaped fast or slow PM pulses or amplifier outputs directly. For highest time resolution, preshaping by means of a discriminator (such as LRS Model 321, 161 or 123) is required.
Input logic is direct-coupled complementary. The presence of a signal is indicated by a negative input voltage of - 700 mV or greater; absence of a signal is indicated by an input voltage of -.1 volts or more positive. The front panel mode switch selects the number of inputs required to trigger an output. It may be set on either "OR" or "AND". (A separate OFF position is also provided, which is useful in set-up and testing to kill the output of the channel regardless of inputs). The various logical possibilities afforded by this arrangement are detailed under the Coincidence Logic heading. Note that all inputs are interchangeable and equivalent, and the logic that a given input performs (i e., Coincidence or Inhibit, or Yes or No) is controlled by the polarity of the input. This degree of flexibility with such a small number of inputs is not possible in AC coupled systems or in systems which do not take full advantage of the possibilities offered by comple- mentary logic.
When the input conditions of a Model 322 channel are satisfied, the unit delivers a set of simultaneous output pulses of preset duration and standard amplitude. Output duration is independent of input amplitude and input duration. Therefore a Model 322 logic channel need not be followed by a discriminator for optimum time resolution. The output duration of the 322 is also independent of input and output rate up to the maximum rate capability of the unit (100 + MHz).
The output duration of the 322 can be continuously preset over a very wide time range. This is a unique and important convenience feature of the instrument, considerably facili- tating set-up time. Further, the Model 322 produces one and only one output pulse each time the input conditions are satisfied; multiple pulses or pulse trains are never produced, no matter how long or how large the input pulses may be. This feature gives the experimenter complete logical freedom in choice of inout and output pulse duration, and eliminates one common and annoying characteristic of most fast logic systems. (Gated pulse bursts for special purposes can be produced by the 322 when desired; see Gated Pulse Burst Genera- tion below).
INPUT CHARACTERISTICS Logic Inputs: Two; direct-coupled; impedance 50 Ohm; reflections < 7% for inputs of 2 ns risetime; NIM levels; (> - 14 mA). Slow (bin) Gate: V ia rear connector, with rear-panel On-Off switch; rise and fall times approximately 50 ns; clamping to ground from + 5 V inhibits; direct-coupled. Inhibit: Either input serves as inhibit when driven with complementary signal . Logic Modes: Off, A or B, A and B; front-panel switch. OUTPUT CHARACTERISTICS Outputs: Three, NIM; one positive (quiescently > - 14 mA, 0 mA during output); two negative (0 mA quies- cently, > - 14 mA during output). Duration: As supplied, continuously adjustable from 5 to approximately 15 ns with front-panel screwdriver potentiometer. Longer duration ranges, to 5 us, may be obtained by adding capacitors to internal terminals provided. Rise and Fall Time: < 2.5 ns, all outputs. GENERAL Functions: Two-fold fan-in and coincidence, or single with inhibit. Coincidence Width: Sum of input pulse durations. Maximum Rate: > 100 MHz input and output. Double-Pulse Resolution: Approximately To/3 + 5.5 ns, where To is output pulse duration. Input-Output Delay: 9.2 +/- .6 ns. Multiple-pulsing: None; one and only one output pulse of preset duration is produced each time the input conditions are satisfied, regardless of the duration of the input pulses or their overlap. Packaging: In conformance with AEC standard for nuclear modules (AEC Report TID-20893); RF shielded AEC #2 module, fitting 6/'bin; dimensions 2.75 X 8.75 X 10 inches deep. Completely compatible physically and el ectri colly with LRS Power Chassis Model 108P, and with any other. AEC power bin of any manufacturer. Power Requirements: + 12 volts at 315 mA; - 12 volts at 435 mA; - 24 volts at 145 mA; all regulated +/- 1%.