Sustainable Status Monitoring of MOSFETs in a Fully Integrated RF Amplifier by Thermal Voltage Sensing of On-Chip Thermopile

Abstract

In this letter, a sustainable status monitoring of MOSFETs in a fully integrated two stage RF amplifier by thermal voltage sensing of on-chip thermopile is implemented in 0.18- $\mu \text{m}$ CMOS technology. The designed micro-thermopile consists of many thermocouples electrically connected in series by Al and P-type polysilicon, which are carefully arranged around the metal-oxide-semiconductor field-effect transistors (MOSFETs). A noteworthy attribute of variations-aware thermopiles, which exhibits an exceptionally close physical proximity to the MOSFETs, is their nonintrusive nature, indicating that they lack electrical connectivity to transistors. During normal operation of the RF amplifier, the dynamic range of its input power spans from −20 to 0 dBm. Experimental measurements on the MOSFETs employed in the first and second power amplification stages are observed to lie within the range of 0.226 to 0.264 and 0.275 to 0.3 mV at 5.4 GHz, respectively. This result demonstrates the capability of integrated on-chip micro-thermopiles to enable continuous monitoring of the operational status of MOSFETs. In comparison to conventional status monitoring approaches, the advantage of this integrated design lies in its elimination of the requirement for supplementary sensors or devices, thereby presenting a significant economic benefit as a low-cost, sustainable monitoring solution in a fully integrated CMOS RF amplifier.