[Moller_intdet] [EXTERNAL] Correction on integrating chain dynamic range

[Michael Gericke]

Hi Devi and everyone,

During Thursday's integrating detector meeting, I stated the wrong 
dynamic range for the integrating detector electronics chain.
The various dynamic ranges (+- 2.048, +- 4.096, Vpp 8.182) that have 
been used in various presentations and documents can be
very confusing, so I wanted to write a short email that clarifies the 
situation:

1) The drawing below illustrates what the LMH5401 amplifier (see 
schematic below) on the preamp board does (roughly), where the 12 uA is 
the signal from the PMT anode.

2) The ADC input needs a positive signal on both differential inputs and 
has a dynamic voltage range of 0 -> 4.096 V on each input.

3) The front-end to the ADC adds an offset of +2.048 V on each ADC 
input, which means we are limited to a +- 2.048V amplitude on each 
differential amplitude line.

4)*This means that we can have anode currents that are consistent with a 
single line signal amplitude of +-4.096 V and a peak-to-peak signal 
swing of maximally 8.182 V.*

5) The stated gain of the preamplifier applies to both differential lines.

I apologize for the confusion my statements may have caused on Thursday.

Cheers,

Michael




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