NIM Model 127D/127DL Dual Bipolar Linear Fan-in

The LRS Model 127D is a fast, versatile bipolar linear fan-in featuring unity gain, non-inverting operation, direct- coupled circuit design and freedom from duty cycle limitations and rate effects. The instrument is based on the proven design of the popular LRS Model 127C, offering improved overload characteristics, output waveshape fidel- ity, and long-term DC stability. The Model 127D operates as either a dual 8-fold linear fan-in or as a single 16-fold linear fan-in. With rise and fall times of less than 2 ns, and an absolute delay of less than 4 ns, the Model 127D may be used to combine nanosecond pulses from as many as sixteen different sources. All inputs are terminated in 50Ohm. Output is linear to +/- 1.5 volts. Pulses may be applied separately or simultaneously to one or both channels; channel inputs and output at ground potential allow compatible interconnection between units. The current source output stage permits paralleling, by external cables, a large number of similar high-output impedance channels. The front-panel pushbutton MIXED switch connects Chan- nel A output to Channel B output. The output amplitude of each channel is the algebraic sum of the input ampli- tudes. Negligible stretching on overload allows use as a logic fan-in of NIM level inputs.

The LRS Model 127D is a member of the leading line of high-speed logic instrumentation in which modern circuit design, components, and packaging are combined in instru- ments of unusually broad usefulness to experimental physicists in both high- and low-energy nuclear research.

The LRS Model 127D is also available as the Model 127DL with Lemo-type connectors in a NIM #1 width module.

SPECIFICATIONS

NIM Model 127D/127DL DUAL BIPOLAR LINEAR FAN-IN

INPUT CHARACTERISTICS
Inputs:	8 per channel; direct coupled. (Unused inputs need not be terminated.)
Impedance:	50 Ohm.
Polarity:	Positive or negative.
Reflection coefficient:	Less than 7% for inputs of 2 ns risetime.
Input protection:	+/-100 V, 10 usec
OUTPUT CHARACTERISTICS
Outputs:	One per channel; direct coupled, current source.
Maximum Amplitude:	Linear region; +/-30 mA. (+/- 1.5 'Volts into 5OOhm). Limits at +/-40 mA (+/-2 volts into 50Ohm).
Rise and fall times:	Less than 2.5 ns, 10% to 90%.
Overshoot:	Less than 7% for 1 ns, 800 mV input pulses (with all unused inputs terminated).
Gain:	Input to output: 1.0 into 50Ohm (20 mA out per volt in.)
Duty cycle limitations:	None.
D.C. offset:	Adjustable with front-panel potentiometer.
Output stability:	Better than 0.5 mV/'C with 50Ohm load.
Stage delay:	4 ns.
Overload recovery:	Approximately 1 ns with eight simultaneous N I M level (-800 mV) inputs.
GENERAL
Output mixing:	A front-panel pushbutton combines the outputs of the two 8-input channels to provide one 16-input channel.
Packaging:	Model 127D - RF shielded AEC/NIM *2 module; dimensions 2.75 x 8.75 x 10 inches deep. BNC connectors. Model 127DL - RF shielded AEC/NIM #1 module; dimensions 1.375 x 8.75 x 10 inches deep. LEMO - type connectors.
Power Requirements:	+24 volts at 130 mA, +1 2 volts at 180 mA, -1 2 volts at 1 1 mA, and -24 volts at 175 mA.