A CMOS temperature detection circuit includes a start-up circuit for generating a start-up voltage, and a proportional to absolute temperature current generator coupled to the start-up circuit for generating a PTAT current. The method can include inserting a first tubing into the wellbore. The method also includes quantifying changes between signal characteristics of real time signals acquired for one or more respective anatomical locations and the at least one SOI that is associated with each of the respective anatomical locations.