First Results with the QIE8 ASIC

1
First Results with the QIE8 ASIC

• A. Baumbaugh, J. E. Elias, J. Hoff, S. Los, C.
  Nelson, T. Shaw, J. Whitmore, R. J. Yarema, T.
  Zimmerman
• Fermi National Accelerator Laboratory
• P.O. Box 500, Batavia, Illinois 60510
• Presented by S. Los
• March 27, 2002

2
Outline

• Introduction to HCAL Readout
• QIE requirements/operation
• QIE8 functional blocks
• Test-bench measurements
• Conclusions

3
CMS HCAL Signal Collection

• QIE is a charge sensitive digitizer located in a
  readout box on or close to the detector.

4
QIE Requirements

• In this table are the very basic requirements for
  the HCAL digitizer. For comparison there is a
  column with its predecessor data.
• The most challenging improvements needed are the
  Noise, Sensitivity, and Analog BW (non-inverting
  input for HF PMT).

5
QIE Block Diagram

• Two Amplifier sets for signals from PMTs/HF and
  HPDs/HBHE
• Four Integrator sets to cover Compare/MuxOut/Reset
  phases when the first set is not integrating

6
Non-Inverting Amp/Splitter

• There are two major requirements to process PMT
  signals
• High bandwidth to integrate the whole signal in a
  25 ns slice, and avoid signal pile-up from other
  beam crossings.
• Stable input impedance to use transmission
  cables, and remove the electronics from high
  radiation zone.

1 up to 1 mA
7
Inverting Amp/Splitter

• HPD has a much smaller gain than a PMT, thus we
  needed following
• Higher sensitivity and lower noise.
• 40 MHz BW to collect the signal in few time
  slices and provide it with a time stamp .

8
QIE8 FADC Ladder Design

• There are two structural changes that made it
  possible to meet our requirements of dynamic
  range, sensitivity, and precision while allowing
  to decrease the number of integration ranges from
  8 to 4.
• Non-linear Ladder design
• Two comparator sets for Regular/Calibration mode
  operation
• Regular mode is piece linear with steps 1?, 2?,
  3?, 4?, 5? wide.
• Calibration mode is linear and uses additional
  taps 1/3 ? on the same ladder.

9
QIE8 Response Function

• Due to proper biasing every conversion range
  covers a dynamic range of about 51 thus
  preserving precision in the beginning of the
  scale.

10
FADC Quantization Error

• Implementation of a 4-range splitter and a 5 bit
  non-linear FADC allows to simplify the design
  while having minimum effect on the detector
  resolution.

11
FADC Linearity

• La

12
FADC Linearity
13
Timing of the Signal
14
Timing of the Signal
15
Calibration Mode DNL
16
2 Channel QIE Board