A technique has been developed to examine the propagation delay change of a CMOS inverter undergoing laser illumination. The injection current into the drain circuit of the inverter assists or opposes the discharge of a load capacitance, thereby speeding or slowing the response of the inverter. A model has been developed that uses the MOSFET large signal equations to predict the behavior of the CMOS inverter in the presence of illumination. The illumination is modeled as an equivalent current source placed across the output. SPICE simulations are conducted to verify the model above, whereas the SPICE model, and the model above, are verified by actual tests. The tests are conducted to characterize 74HCU04 inverter behavior for continuous and pulsed illumination. The pulsed illumination test used laser pulses from 10 ns to 100 ns wide positioned from 50 ns before to 50 ns after an input change to the inverter. The test data is in the form of a profile that clearly shows the propagation delay change. The SPICE model and theoretical model match well, as is expected, and both have good correspondence with the test data
