Measurement of Self-Heating of High-Frequency CMOS Clock Buffers

A technique is presented to measure the temperature of a large, dense, CMOS clock buffer while it is operating. The technique uses the subthreshold slope of a single pFET, thereby avoiding introducing special technology enhancements for thermal sensing, and uses purely simple electrical measurements. The technique is demonstrated to work in the presence of high-frequency digital switching in a realistic test site fabricated in a 14 nm finFET technology.