NIM Model 612A
12-Channel Photomultiplier Amplifier

 * 12 channels/#l NIM module
* 2 identical 50 Ohm outputs per channel
* Gain of 10, direct-coupled
* Input and Output protected against overload
* <2 nsec risetime
* <1 mV dc stability (short and long term) at the output
* -5 volt linear range (5000:1 usable dynamic range)
* 0.1% integral linearity
* Low cost

The LeCroy Model 612A is a new 12-channel, 200 MHz bandwidth, gain of 10 lin- ear amplifier packaged in a #1 NIM module. Representing a major advance in fast amplifier stability, dynamic range, and general utility, the 612A allows the experi- menter for the first time to consider the use of economical, lower gain pho- tomultiplier tubes even in demanding direct-coupled ADC applications. The Model 612A offers a built-in fan-out of two, simplifying simultaneous use of the same photomultiplier signal for both analog and logic purposes by eliminating the extra cable run necessary when both anode and dynode signals are used. Packaged 12 channels per module, the 612A offers substantial savings in bin space and is di- rectly compatible with standard LeCroy 12-channel ADC's and multichannel dis- criminators.

A new high-speed operational amplifier circuit design makes the performance of the amplifier virtually independent of external variables such as supply voltages or temperature. Input and output DC levels remain negligibly small even when the module is moved from bin to bin, or under extremes of operating temperature. There is virtually no warm-up drift on turn-on. These stability characteristics, to- gether with the excellent linearity, speed and noise characteristics of the circuit, come very close to the ideal of a "transparent gain" element that simply magnifies the input without significant distortion or operating constraints.

The Model 612A normally operates from +6, +/-12, and -24 volts. A rear-panel switch permits operation from -6 instead of -12 volts for those applications in which -6 volts is easily available and where a moderate saving in power consumption is more important than dynamic range. When operated from -6 volts, maximum output amplitude is reduced from -5 to -2 volts. In either case, the large output levels available reduce recovery time problems associated with overload.




50 Ohm.

Input Protection:

+/-5 A for 0.5 Asec; +/-500 mA continuous input voltage; clamps at +/-0.6 V.

Reflection Coefficient:

Less than 5% over input dynamic range.

Quiescent Voltage:

+/-0.5 mV.

OUTPUT CHARACTERISTICS (Both outputs of each used channel must be terminated for optimum waveshape.)

Maximum Positive Amplitude (Linear):

+200 mV.

Maximum Negative Amplitude (Linear):

-2 volts with -6 V supply; -5 volts with -12 V supply.


Less than +/-10% for input risetimes >=1.5 nsec.

Quiescent Voltage:

0 V +/-3mV.

Output Voltage DC Offset Temperature Coefficient:

100 uV/'C maximum.

Output Voltage Variation with Supply Voltage:

<1 mV for +/-1% variation of any supply voltage.



Fixed gain of 10, non-inverting. Long-term stability 1 %. Gain tolerance +/-5%.


0.1 % integral.




< 2.0 nsec, 1 0% to 90%.


Approx. 4 nsec.


Less than 50 uV rms, referred to input, total.

Interchannel Crosstalk:

Output in one channel affects any other channel by no more than -70 dB.

Overload Recovery:

a) Operation with -12 volt supply: saturated for approximately 15 nsec after 1 OX overload.
b) Operation with -6 volt supply: saturated for approximately 50 nsec after 1 OX overload. For wide pulses (i.e., > 5 usec) it is recommended to use - 12 V supply for best overload recovery.


RF-shielded AEC/NIM #1 width module conforming to specifications outlined in AEC Report TID-20893; Lemo-type connectors.

Current Requirements:

In rear panel selected 6 V mode:
+6 V at 350 mA,
-6 V at 275 mA,
+12 V at 5 mA,
-12 V at 5 mA,
-24 V at 80 mA,

or in 12 V mode:
+6 V at 350 mA
+12 V at 5 mA,
-12 V at 275 mA,
-24 V at 80 mA.

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