ADC Module - Analog Input Channel



The schematic of the Analog Input Channel Rev. B, configured for no input offset, is persented here: ADC_Preamp_RevB.pdf

As shown, the circuit provides a full-scale digital readout for a differential input PMT pulse of about 1.5Vpp. In low frequency, the same circuit provides a full-scale digital readout for a differential input of about 1.1Vpp. Because of the 10-pole low-pass filter, the overall gain depends on the frequency. The gain is controlled by changing resistors: A0_18, A0_82. (E.g. for a low-frequency gain of one, we would need A0_18, A0_82 = 100 Ohm.)

Plot1. This plot presents the low-frequency differential signal that is applied at the input of the circuit, and generates a full-scale digital recording:

The oscilloscope plots with the signal before the shaper and after the shaper, as well as the corresponding digital recording, are also presented.

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Plot 2. This plot presents a PMT-like differential signal (5ns rise, 28ns trail), that is applied at the input of the circuit, and generates a full-scale digital recording:

The oscilloscope plots with the signal before the shaper and after the shaper, as well as the corresponding digital recording, are also presented.

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Plot 3. This plot presents a very narrow, PMT-like differential signal (2ns rise, 12ns trail), that is applied at the input of the circuit, and generates a full-scale digital recording:

The oscilloscope plots with the signal before the shaper and after the shaper, as well as the corresponding digital recording, are also presented. This pulse is very narrow and it gets attenuated even before the shaper.


 



 
For questions regarding this page contact Mircea Bogdan.
bogdan@edg.uchicago.edu
Revised: Oct. 1, 2008