Diagnosis and analysis of an analog circuit failure using time resolved emission microscopy

Acquiring the waveforms of internal nodes in an operating integrated circuit has been a key technique in understanding and resolving design and process related anomalies for many years. Time resolved emission (TRE) has emerged as a technique of choice for acquiring waveforms from the backside of digital ICs. This paper describes the techniques used for diagnosing an analog level problem in a mixed signal IC, employing a TRE system as the main debugging tool. This debug effort is significant in the sense that a backend failure analysis tool that is typically dedicated to digital circuits was used for the first time to successfully diagnose an analog fault on an asynchronous timing path. A design-for-debug strategy adopted early in the design cycle proved to be important in allowing timely TRE failure analysis resolution of this device