A CMOS TIME TO DIGITAL CONVERTER IC WITH 2-LEVEL ANALOG CAM

A time to charge converter IC with an analog memory unit (TCCAMU) has been designed and fabricated in HP's CMOS 1.2-mum n-well process. The TCCAMU is an event driven system designed for front end data acquisition in high energy physics experiments. The chip includes a time to charge converter, analog Level 1 and Level 2 associative memories for input pipelining and data filtering, and an A/D converter. The intervals measured and digitized range from 8-24 ns. Testing of the fabricated chip resulted in an LSB width of 107 ps, a typical differential nonlinearity of < 35 ps, and a typical integral nonlinearity of < 200 ps. The average power dissipation is 8.28 mW per channel. By counting the reference clock, a time resolution of 107 ps over approximately 1 s range could be realized.