Chips at Work: Picosecond Imaging Circuit Analysis

Picosecond pulses of hot electron luminescence are observed from individual submicron FETs in CMOS circuits. The pulses are synchronous with logic state switching. We have developed a method to simultaneously image and time resolve this weak emission. The emission has been used to measure AC operation of integrated circuits from a simple ring oscillator to a full microprocessor. Examples of circuit characterization and fault diagnosis are presented.