This page documents a proposed 12-bit WFD for PMT pulse digitization. The goal is initially to engineer an ADC/FPGA/memory block which is relatively straightforward and which could be replicated to produce a multi-channel unit with a (unspecified as of now) computer interface.

Some guideline specs for a production unit:

• 12 or more bits resolution
• 250MSPS or faster digitization
• Front-end with 250MHz bandwidth to support interleaving of two FADCs at 500MSPS (or 500MSPS ADC). 12 bit analog performance, capable of 0.1mV least count operation.
• generic memory interface (SDRAM) capable of 2x ADC speed (500MB/sec) throughput.
• 50 ohm single-ended DC-coupled analog input, with adjustable gain and DC offset.
• Baseline adjust such that both negative-going and positive-going signals can be accommodated
• Convenient mechanism to combine multiple channels to extend dynamic range in pulse height or time (interleaving).

I would suggest an initial prototype with the following characteristics:

• 50 ohm input, providing 0-4.095V (1mV/count) and 0-409.5mV (0.1mV/count) ranges.
• On-board digitizer clock source, with external (sine wave) clock option
• Suitable FADC and FPGA (Xilinx)
• SDRAM with sufficient bandwidth
• Ethernet (or USB-2) interface

'1GSPS and Beyond

•  ADC12D500RF
•  ADS5400
•  ADC12D1000
•  ADC10D1000
•  MAX104
•  EV10AQ190TPY

'Candidate ADCs

•  AT84AS001 •  now e2v • 5/09 Arrow $163 ea
•  ADS5463 sample received. ($135 ea @ 1k per TI website 3/2012)
  • 500MSPS_Prototype
•  ADS5444 (13 bits, 250MSPS) - stock on 8/23/06 ($76 ea @100) have_samples?
•  ADS5440
•  AD9230
•  MAX1215
•  LTC2242-12 (12 bits, 250MSPS) have_samples?

'Other Parts

•  THS4509 wideband differential op-amp have_samples? Recommended to drive ADS5444. As of 4/5/07: THS4509RGTT 163pcs stock at Digikey 8.30

in small qtys, 5.60250 100pcs other distributers have stock as well

Existing Products

•  Acquris
  •  DC440