Digital Circuits for Photon- Counting Pixel Detectors
Discriminator
Counter Pre-amplifier
Pulse shaper
Detector Comaprators
Analog
Digital
Photon counting pixel
with window discrimination
Pixel array
All-digital window discriminator
• Objective
– Design an efficient window discriminator with – small circuit area
– that is modular and
– that does not rely on internal or external timing references
• Outline
– Problem description
– Design of the window discriminator
– Results
Problem description
Design
• Capture the behavior of the clock generator (ADWD)
– The sequence of the input signal (LT,UT) will determine the clock signal (C) generation
– Identify the states of the ADWD
Logic design (cont.)
Logic synthesis
- assume fundamental mode operation
- use transition diagram
Results
• ADWD module
– Area: 350 m in a 0.6 m CMOS process
– Speed
• minimum time between two consecutive pulses: 600 ps
• minimum resolution time for window size: 100 ps
