Thermal laser signal injection microscopy (T-LSIM) (aka TIVA and OBIRCH) has shown considerable promise in stateof- the-art digital integrated circuits. The technique has been utilized to locate shorts, leakage currents, problem vias, and timing issues in these devices. However, little has been published on the utility of this technique for analog and mixed signal devices. In this paper we demonstrate the application of T-LSIM on two different analog devices with defects that conventional FA technology and fault isolation techniques were unable to locate. Analog devices produce several unique challenges to the basic T-LSIM technique as typically utilized in the digital regime. Extensions of the basic T-LSIM technique were utilized to locate the failures, which produced unexpected results. The T-LSIM technique has proved essential in the quick identification and localization of failure sites. The T-LSIM technique provides the failure analyst with the analytical power not previously available on conventional fault isolation tools such as emission microscopy and liquid crystal.