A CMOS time measurement system with analog memory for particle physics detectors

A time-to-charge converter with an analog memory unit (TCC/AMU) has been designed and fabricated in HP's 1.2 mu m n-well process. This VLSI chip is intended for the Superconducting Super Collider straw tube detector electronics. The TCC/AMU measures the time interval between the system clock and an asynchronous input, and then gives a digital output representing the time measurement. This initial version of the chip has analog Level 1 and Level 2 storage locations for data sparsification. Two separate fabrication runs resulted in chips that can measure intervals from 8 to 24 ns with approximately 108 ps/LSB resolution. When digital logic is added to count the reference clock, time resolutions of approximately 108 ps could be obtained over time intervals of approximately 1 s.<>