A monolithic gallium arsenide interval timer IC with integrated PLL clock synthesis having 500-ps single shot resolution

A gallium arsenide (GaAs) integrated circuit for measuring single shot time intervals with 500-ps resolution has been designed, fabricated, and tested. The circuit contains a 12-b counter that can be extended externally and control circuitry for the detection of multiple intervals. Options such as number of intervals, minimum interval time, and timing resolution are user programmable. The circuit employs a self-contained 2.0-GHz phase-locked loop (PLL) clock synthesizer with less than 5 ps rms jitter and a lock time of 2.5 μs. The circuit is packaged in a 14-mm², 52-pin thermally enhanced plastic package and operates from a single +5-V supply. The nominal power dissipation is 2.8 W. The circuit is fabricated in a 0.6-μm gate length, enhancement/depletion GaAs MESFET process utilizing four layers of gold interconnect metallization. Inductors, capacitors, and thin film resistors can be fabricated in this process, enabling integrated analog circuitry. The die size is 3.28 by 3.15 mm. The circuit has applications in collision avoidance sensors, laser rangefinders, surveying, police radar, and test instrumentation