ABSTRACT
In several applications it is important to perform an accurate measurement of the time at which a given hit occurs. A common example is provided by time-of-ight (TOF) techniques employed for particle identication in high-energy physics experiments (Green 2000). Time-of-ight telescopes based on semiconductor radiation
12.1 Introduction ................................................................................................ 315 12.2 Time Resolution ......................................................................................... 317
12.2.1 Timing Errors due to Noise ......................................................... 317 12.2.2 Timing Errors due to Amplitude Variations ................................ 318
12.3 Constant-Fraction Discriminator ............................................................... 321 12.3.1 Principle of Operation .................................................................. 321 12.3.2 Issues in Monolithic CFD Design ................................................ 323 12.3.3 Practical CFD Implementations ................................................... 324
12.4 Time-Walk Correction with Amplitude Information ................................. 328 12.4.1 Time-over-Threshold: Basic Principle and Practical
Implementations ........................................................................... 328 12.4.2 Time Resolution of a Low-Power ToT Cell in 0.13-Nm
CMOS: A Case Study .................................................................. 330 References .............................................................................................................. 334
detectors have been used for decades in nuclear physics (Spieler 1982). In these systems, a thin device senses the passage of a particle and generates a start signal, while a thick sensor stops the particle and measures its energy. An accurate measurement of the time elapsed between the two events combined with the energy information leads to the particle mass. The number of channels now in use for similar applications in low-and medium-energy nuclear physics justies the need of high-density integrated front-end electronics incorporating on chip both energy and timing capabilities. A 16-channel chip allowing an energy resolution of 38 keV and a time resolution of 1-ns FWHM (full width at half maximum) has recently been reported (Engel et al. 2007).
