Confirmation of calculated error rates in a logic circuit using a pulsed laser

Understanding the generation and propagation of single event upsets (SEU) induced by energetic ions passing through logic circuits is difficult due to the fact that neither the location of the ion strike, nor the time at which it occurs, can readily be determined. The task is greatly simplified with a pulsed laser because the laser light can be focused to a small spot and positioned on a particular node in the circuit, making it possible to identify the location of the upset. Furthermore, the time at which the upset occurs can also be established by synchronizing the laser pulse to the circuit clock. In this way, a great deal of information regarding the sensitivity of logic circuits to SEUs can be obtained. We have used the pulsed laser to generate upsets in a logic circuit. The measured upset rates agreed quite well with calculated error rates.