A CMOS time to digital converter for space science instruments

A TDC implemented in CMOS with a maximum of 50ps resolution is presented. The TDC has a dynamic range of 11bit and power consumption below 20mW at an event rate of 500Kevents/sec. The chip was designed to operate in a wide temperature and power supply range, and for a wide LSB range(tested 50-800ps). High counting rate (over 1Mevents/sec for LSB = 100ps) was also a priority. The TDC was incorporated in the Time of Flight(TOF) chip [9] used in the H.E.N.A.(High Energy Neutral Atoms)imager of the IMAGE NASA mission and planed for many other instruments.