TID characterization of high frequency RF circuits in NANO-CMOS technologies

Abstract

Rapid downscaling of CMOS technology has resulted in significant improvement in the RF performance of Silicon MOSFETs. As a result, standard CMOS technology has become a popular choice for implementing RF applications. Nano-scale CMOS device characteristics can be highly sensitive to variations in process (P), supply voltage (V) and operating temperature (T). This makes the design of RF circuits using nano-scale CMOS devices increasingly challenging to satisfy the performance specifications across all PVT corners. Another parameter that needs to be considered in the design space for RF circuits used in aerospace and military applications is total ionizing dose (TID) irradiation. Even a relatively small amount of TID-induced degradation that may not be significant for typical digital CMOS applications can be quite important for analog RF applications, especially when compounded by PVT variations. Radiation experiments show degradation in the performance of a 20.4 GHz voltage controlled oscillator (VCO) designed and fabricated in the IBM 32 nm CMOS SOI technology. At elevated temperature, the TID-induced degradation in the VCO performance is further enhanced causing failure to meet required design specifications. Measured TID-induced DC and RF parametric degradation of NMOS and PMOS transistors in the IBM 45 nm CMOS SOI technology were used to develop compact models. These models were used in example K-band RF circuits, such as the VCO and a low noise amplifier (LNA), to predict TID-induced degradation in the circuit performance. The circuit simulations show consistent results, predicting specification failures in these RF circuits due to the combined effects of PVT corners and TID. The failure to meet design specifications of a circuit can in turn cause the failure of the entire RF system. The TID-aware compact models are further used to suggest radiation hardened by design (RHBD) alternatives along with tradeoff study of RF circuit performance and its radiation response. This study provides valuable design and reliability insights for RFIC designers targeting military and aerospace applications.