Lock-in Amplifier Applications for Fault Isolation

Abstract This paper describes how lock-in amplifiers and boxcar averaging can overcome limitations in conventional fault isolation techniques for microelectronic testing. Our approach achieves superior results compared to traditional spectrum analyzer methods through three key applications. First, we measure the signal-to-noise ratio of individual pulses during laser voltage tracing (LVT) across varying pulse widths. Second, we leverage enhanced LVT imaging to improve computer-aided design to stage alignment and laser voltage probe placement—a crucial advancement for analyzing compressed scan and streaming scan network test failures. Finally, we present a case where our Lock-In amplifier system successfully generates pass/fail signals for dynamic laser stimulation in scenarios where conventional test hardware proved inadequate.